Infectious Diseases

Infectious Diseases, General Health & Wellness

Rubella virus is the cause of German measles, usually a mild exanthem, often subclinical; however, when acquired in utero, rubella virus can cause congenital rubella syndrome and lead to fetal demise, malformation, deafness and intellectual disability.This assay can serve as an assessment of immune status in women of child bearing age to support decisions around vaccination and prophylaxis. Detection of IgG following acute infection can aid in the diagnosis of rubella.

Autoimmune & Inflammation, Infectious Diseases

Increased monoclonal IgA may be produced in lymphoproliferative disorders, especially multiple myeloma and “Mediterranean” lymphoma involving bowel. An IgA monoclonal peak >2 g/dL is a major criterion for myeloma. It may be elevated in a wide range of conditions affecting mucosal surfaces, where IgA is largely produced. Some clinically significant IgA deficiencies have concomitant deficiencies of IgG2and IgG4. IgA may be decreased in patients with chronic sinopulmonary disease, in ataxia-telangiectasia, or congenitally. Patients with congenital IgA deficiency are prone to autoimmune diseases, and may develop antibody to IgA and anaphylaxis if transfused. IgA levels may rise with exercise and fall during pregnancy.

Infectious Diseases

Streptolysin is a hemolysin produced by group A streptococci. In an infected individual streptolysin O acts as a protein antigen, and the patient mounts an antibody response. A rise in antibody level begins about one week after infection and peaks two to three weeks later. In the absence of complications or reinfection, the ASO titer will usually fall to preinfection levels within 6 to 12 months. Both clinical and laboratory findings should be correlated in reaching a diagnosis.

Infectious Diseases

A positive test in the presence of consistent clinical and/or hematologic findings confirms the diagnosis of infectious mononucleosis. Approximately 10% of mononucleosis syndromes are heterophil-negative. In some of these, antibody to specific Epstein-Barr viral antigen can be demonstrated. Others may be due to CMV, HSV, or toxoplasmosis. Although this classic test has excellent specificity, false-positive tests can occur and may lead to diagnostic confusion.

Infectious Diseases

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Infectious Diseases

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Autoimmune & Inflammation, Infectious Diseases

Useful in differentiating inflammatory and neoplastic diseases and as an index of disease severity. CRP is also useful in monitoring inflammatory disease states.

Infectious Diseases

Measles virus (rubeola) is a member of the Paramyxoviidae family of viruses which includes the parainfluenza viruses, mumps, and respiratory syncytial virus. Measles is a highly contagious rash illness that is transmitted from person to person by direct contact with respiratory droplets generated through coughing and sneezing. Ninety percent of susceptible persons exposed to measles infected individuals will go on to develop measles. Although vaccination is highly effective against measles virus and the United States was declared free from endemic measles in 2000, travel-associated cases and spread among unvaccinated individuals continues to occur resulting in local measles epidemics.Acceptable presumptive evidence of Measles Immunity:Per the Centers for Disease Control and Prevention (CDC), acceptable presumptive evidence of immunity against measles virus includes at leastoneof the following:• Documentation of age-appropriate vaccination against measles virus.• Laboratory evidence of immunity (IgG in serum; equivocal results should be considered negative).• Laboratory confirmation of measles.• Birth before 1957.

Infectious Diseases

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Infectious Diseases, General Health & Wellness

Offered as part of multiple lab tests

Infectious Diseases, General Health & Wellness

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Infectious Diseases, Digestive Health

C difficilecan produce two toxins, designated A and B, that have pathogenic effects in humans. Antibiotic-associated pseudomembranous colitis has been shown to result from the action of these two toxins. This disease has been associated with clindamycin use but it is now recognized that pseudomembranous colitis can follow administration of virtually any antibiotic. More than 70% of the cases in a large series were associated with cephalosporin therapy.1The clinical spectrum of antibiotic-induced syndromes caused byC difficileincludes patients with symptoms of acute abdomen with little or no diarrhea, as well as cases with fulminant life-threatening diarrhea. Nosocomial transmission and reinfection with different strains occurs as do spontaneous cases without prior antimicrobial therapy. In cases where cessation of antibiotic therapy does not produce a response, specific therapy with oral vancomycin, metronidazole, or oral bacitracin may be effective. Detection of the toxins produced byC difficile(rather than culture of the organism) is important in the determining therapy of this potentially fatal disease. The routine use of culture does not seem appropriate because of the costs and the high rate of recovery of strains which do not produce toxin.

Sexual Health & STDs, Infectious Diseases

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Infectious Diseases, Digestive Health

The diagnosis ofSchistosoma haematobiuminfection is achieved by examination of urine specimens for eggs. Both 24-hour and spot urine samples should be examined to enhance detection.S haematobiumegg excretion exhibits a circadium rhythm, with the peak occurring between noon and 3 PM. Egg output is enhanced by physical exercise combined with fluid intake prior to urination. In very light or chronic infections, eggs may be very difficult to detect in urine; consequently, multiple urine sample examinations may be required. Occasionally eggs ofS mansonimay also be detected in urine.

Sexual Health & STDs, Infectious Diseases

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Infectious Diseases, Digestive Health

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Autoimmune & Inflammation, Infectious Diseases

Increased CRP levels are found in inflammatory conditions including: bacterial infection, rheumatic fever, active arthritis, myocardial infarction, malignancies and in the post-operative state. This test cannot detect the relatively small elevations of CRP that are associated with increased cardiovascular risk.

Infectious Diseases

RPRRPR titerTreponemal Ab (TPAb)InterpretationNonreactiveNot performedNot performedNo laboratory evidence of syphilis. If recent exposure is suspected, submit a new sample for testing in 2-4 weeks.Reactive1:1 or higherNonreactiveNontreponemal antibodies detected. Syphilis unlikely; biological false positive possible. Clinical evaluation should be performed to identify current signs and symptoms or past history of infection or treatment. If recent exposure is suspected, submit a new sample for testing in 2-4 weeks.Reactive1:1 or higherReactiveTreponemal and nontreponemal antibodies detected. Consistent with past or current (potentially early) syphilis. Clinical evaluation should be performed to identify current signs and symptoms or past history of infection or treatment.

Infectious Diseases, Liver & Kidney Health

HAV is a picornavirus primarily transmitted via the fecal-oral route. HAV replicates in the liver and is shed in high concentrations in feces from 2-3 weeks before to 1 week after the onset of clinical illness. IgM antibody develops within a week of symptom onset, peaks around three months, and is usually no longer detectable after six months. Many cases of hepatitis A are subclinical, particularly in children. Antibody produced in response to HAV infection (anti-HAV) persists for life and confers protection against reinfection. The presence of IgM antibody to HAV is diagnostic of acute HAV infection. A positive test for total anti-HAV indicates immunity to HAV infection but does not differentiate current from previous HAV infection. Although usually not sensitive enough to detect the low level of protective antibody after vaccination, anti-HAV tests also might be positive after hepatitis A vaccination.

Autoimmune & Inflammation, Infectious Diseases

Decreased C3 may be associated with acute glomerulonephritis, membranoproliferative glomerulonephritis, immune complex disease, active systemic lupus erythematosis, and generalized autoimmune processes.

Autoimmune & Inflammation, Infectious Diseases

Decreased C4 level is associated with acute systemic lupus erythematosis, glomerulonephritis, immune complex disease, cryoglobulinemia, congenital C4 deficiency and generalized autoimmune disease.

Autoimmune & Inflammation, Infectious Diseases

Increased IgA is associated with monoclonal IgA myeloma, respiratory and gastrointestinal infections, and malabsorption; decreased IgA is found in selective IgA deficiency and in ataxia telangiectasia.

Infectious Diseases

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Infectious Diseases

Measles, also known as rubeola, causes fever, irritability, respiratory illness, and the characteristic skin rash. Immunization has greatly diminished the incidence of measles. The presence of IgG is consistent with immunity or prior exposure. IgM is consistent with current or recent infection. IgM tests can generate false positive results and low levels of IgM can persist for longer than 12 months.

Infectious Diseases, Sexual Health & STDs

Varicella-Zoster Virus (VZV) causes chicken pox and when reactivated, potentially decades later, causes shingles. Twenty percent of adults will develop shingles, a rash or blister of the skin that may cause severe pain. Varicella-Zoster IgG, EIA reliably measures immunity due to previous infection, but is unsuitable for detection of post-vaccination immune status.

Infectious Diseases, General Health & Wellness

Heterophile antibodies, in patients with infectious mononucleosis, may be present as early as the fourth day of illness, and by the twenty-first day of illness, 90% of patients will exhibit a positive test. The Epstein-Barr virus causes infectious mononucleosis.

Infectious Diseases, Liver & Kidney Health

This culture is designed to quantitate the growth of significant bacteria when collected by the Clean Catch Guidelines or from indwelling catheters.  Quantitative culturing of urine is an established tool to differentiate significant bacteruria from contamination introduced during voiding. This test has a reference range of less than 1,000 bacteria per mL. More than 95% of Urinary Tract Infections (UTI) are attributed to a single organism. Infecting organisms are usually present at greater that 100,000 per mL, but a lower density may be clinically important. In cases of UTI where more than one organism is present, the predominant organism is usually significant and others are probably urethral or collection contaminants. When multiple organisms are isolated from patients with indwelling catheters, UTI is doubtful and colonization likely.

Infectious Diseases, Sexual Health & STDs

Surface antigen usually appears in the serum after an incubation period of 1 to 6 months following exposure to Hepatitis B virus and peaks shortly after onset of symptoms. It typically disappears within 1 to 3 months. Persistence of Hepatitis B Surface Antigen for greater than 6 months is a prognostic indicator of chronic Hepatitis B infection.

Infectious Diseases

Mumps is an acute, usually self-limited systemic illness characterized by parotiditis, high fever and fatigue. One third of infections are asymptomatic.

Infectious Diseases

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Autoimmune & Inflammation, Infectious Diseases

Increased IgG is associated with acute and chronic inflammations, monoclonal IgG myeloma, autoimmune diseases; decreased IgG is found in selective IgG deficiency, Bruton's Disease, and acquired immune deficiency.

Sexual Health & STDs, Infectious Diseases

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Infectious Diseases

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Infectious Diseases

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Sexual Health & STDs, Infectious Diseases

UreaplasmaandMycoplasmacan be isolated from urethral and genital swabs and from urine of sexually active individuals. Sixty percent or more of all women asymptomatically carryU urealyticumin their genital tract. Usual prevalence of these organisms in patients with urethral symptoms also is high; thus, conclusions regarding the etiologic role of an isolate in a given patient are difficult to make. Nevertheless,Ureaplasma urealyticumhas been associated with cases of nongonococcal urethritis.

Infectious Diseases, General Health & Wellness

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Sexual Health & STDs, Infectious Diseases

This is a non-treponemal screening test for syphilis. False positive results may occur due to systemic lupus erythematosus, leprosy, brucellosis, atypical pneumonia, typhus, yaws, pinta, or pregnancy. Monitoring of RPR is helpful in assessing effectiveness of therapy.

Infectious Diseases, Autoimmune & Inflammation

This test is a sensitive test for recentstreptococcalinfection. A rise in ASO begins about one week after infection and peaks two to four weeks later. ASO levels do not rise with cutaneous infections. In the absence of complications or reinfection, the ASO level will fall to preinfection levels within 6 to 12 months. Over 80% of patients with acute rheumatic fever and 95% of patients with acute glomerulonephritis due tostreptococcihave elevated levels of ASO.

Infectious Diseases

CMV causes an infectious mononucleosis syndrome clinically indistinguishable from heterophil positive mononucleosis. Signs include fever, malaise, and increased transaminase levels without jaundice.

Infectious Diseases

Toxoplasma gondiiis endemic in cats and is excreted by them in their feces. Humans are easily exposed to cyst forms, and the majority develop antibody without any clinical disease. A self-limiting lymphadenitis is the most common clinical presentation in symptomatic infection. Congenital toxoplasmosis and infections in AIDS patients are more serious.

Infectious Diseases

Rubella is an acute exanthematous viral infection of children and adults. Rash, fever and lymphadenopathy characterize the illness. While many infections are subclinical, this virus has the potential to cause fetal infection with resultant birth defects.Diagnosis of a Rubella infection is best made serologically. In the absence of a current or recent infection, a demonstration of specific IgG on a serum sample is evidence of immunity to Rubella.

Infectious Diseases

CMV infections are common and usually asymptomatic. In patients who are immunocompromised, CMV may cause disseminated, severe disease. CMV may cause birth defects in a minority of infected newborns.

Infectious Diseases

CMV infections are common and usually asymptomatic. In patients who are immunocompromised, CMV may cause severe disseminated disease. CMV may cause birth defects in a minority of infected newborns. CMV IgG antibodies may represent prior exposure or recent infection.

Infectious Diseases

Toxoplasmosis is a parasitic infection caused by the protozoanToxoplasma gondii. Approximately 23% of the immunocompetent population are asymptomatic carriers of the parasite. High titers of IgG antibodies toToxoplasma gondiican persist for years. Rising IgG titers after birth, in the absence of a placental leak, are consistent with neonatal infection.

Infectious Diseases, Sexual Health & STDs

Hepatitis C Virus (HCV) is a major cause of hepatitis. The clinical symptoms of an HCV infection are variable. Infection with HCV results in a chronic infection in 50 to 80% of cases. The "window" between HCV acquisition and seroreactivity is highly variable; up to six months.

Sexual Health & STDs, Infectious Diseases

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Infectious Diseases

Provides both IgM and IgG Line blot results. Increased specificity reduces cross-reactivity from other spirochetes. Detect and analyze antibodies against specificB burgdorferiproteins. The sensitivity of a Line blot assay by itself is not sufficient to assess Lyme infection adequately. Both EIA and Line blot tests should be performed.

Infectious Diseases

MeaslesAcceptable presumptive evidence of Measles Immunity (at least one of the following):• Documentation of age-appropriate vaccination against measles virus.• Laboratory evidence of immunity (IgG in serum; equivocal results should be considered negative).• Laboratory confirmation of measles.• Birth before 1957.Persons who have measles-specific IgG antibody that is detectable by any commonly used serological assay are considered to have adequate laboratory evidence of measles immunity. Persons with an equivocal serologic test result do not have adequate presumptive evidence of immunity and should be considered susceptible unless they have other evidence of measles immunity.Documented age-appropriate vaccination supersedes the results of subsequent serologic testing. If a person who has two documented doses of measles-containing vaccine is tested serologically and is determined to have negative or equivocal measles results, it isnotrecommended that the person receive an additional dose of vaccine. Such persons should be considered to have presumptive evidence of immunity.MumpsAcceptable presumptive evidence of Mumps Immunity (at least one of the following):• Documentation of age-appropriate vaccination against mumps virus.• Laboratory evidence of immunity (IgG in serum; equivocal results should be considered negative).• Laboratory confirmation of disease.• Born before 1957.RubellaAcceptable presumptive evidence of Rubella Immunity (at least one of the following):• Documentation of 1-dose of live rubela virus-containing vaccine.• Laboratory evidence of immunity (IgG in serum; equivocal results should be considered negative).• Laboratory confirmation of disease.• Born before 1957 (except women of childbearing age who could become pregnant).

Infectious Diseases, Liver & Kidney Health

Hepatitis B surface antigen (HBsAg) is a protein on the surface of hepatitis B virus that can be detected in high levels in serum during acute or chronic hepatitis B virus infection. The presence of HBsAg indicates that the person is infectious. HBsAg can typically be detected in an infected person's blood an average of 4 weeks (range: 1-9 weeks) after exposure to the virus. Persistence of HBsAg, without anti-HBs, with combinations of positivity of anti-HBc, HbeAg, or anti-HBe indicates infectivity and the need for investigation for chronic persistent or chronic aggressive hepatitis.The presence of Hepatitis B surface antibody (anti-HBs) is generally interpreted as indicating recovery and immunity from hepatitis B virus infection. Anti-HBs also develops in a person who has been successfully vaccinated against hepatitis B.Total hepatitis B core antibody (anti-HBc) appears at the onset of symptoms in acute hepatitis B and persists for life. The presence of anti-HBc indicates previous or ongoing infection with hepatitis B virus in an undefined time frame. IgM antibody to hepatitis B core antigen (IgM anti-HBc) positivity indicates recent infection with hepatitis B virus (< 6 months) and its presence is consistent with acute infection.HBV Serology Interpretation: Key: Analyte present: + Analyte absent: - Test not indicated: TNIInterpretationHBsAganti-HBsanti-HBcIgM anti-HBc* Multiple possibilities: resolved infection (most common); false-positive anti-HBc (susceptible); "low-level" chronic infection; resolving acute infection.Susceptible/no evidence of infection---TNIImmune due to natural resolved infection-++TNIImmune due to vaccination-+-TNIAcute infection+-++Chronic infection+-+-Interpretation unclear*--+±

Infectious Diseases, General Health & Wellness

Sequential blood cultures in nonendocarditis patients using a 20 mL sample resulted in an 80% positive yield after the first set, a 90% yield after the second set, and a 99% yield after the third set. Volume of blood cultured seems to be more important than the specific culture technique being employed by the laboratory. The isolation of coagulase-negativeStaphylococcusposes a critical and difficult clinical dilemma. Although coagulase-negativeStaphylococcusis the most commonly isolated organism from blood cultures, only a few (6.3%) of the isolates represent “true” clinically significant bacteremia.2Conversely, coagulase-negativeStaphylococcusis well recognized as a cause of infections involving prosthetic devices, cardiac valves, CSF shunts, dialysis catheters, and indwelling vascular catheters.3Ultimately, the physician is responsible for determining whether an organism is a contaminant or a pathogen. The decision is based on both laboratory and clinical data. Frequently this determination includes patient data (ie, patient history), physical examination, body temperatures, clinical course, and laboratory data (ie, culture results, white blood cell count, and differential). The number of positive cultures as defined by a venipuncture is the most relevant criterion to use in determining whether an isolate is a contaminant. Clinical experience and judgment may play a significant role in resolving this clinical dilemma.4In patients who have received antimicrobial drugs, four to six blood cultures may be necessary. Any organism isolated from the blood is usually tested for susceptibility. It is not recommended to culture blood while antimicrobials are present unless verification of an agent's efficacy is needed. This is confirmed with a single culture.The diagnosis of bacterial meningitis is accomplished by blood culture, as well as culture and examination of the cerebrospinal fluid.5Most children with bacterial meningitis are initially bacteremic.6See tables.Blood Culture CollectionClinical Disease SuspectedCulture RecommendationRationalSepsis, meningitis osteomyelitis, septic arthritis, bacterial pneumoniaTwo sets of cultures—one from each of two prepared sites, the second drawn after a brief time interval, then begin therapy.Assure sufficient sampling in cases of intermittent or low level bacteremia. Minimize the confusion caused by a positive culture resulting from transient bacteremia or skin contamination.Fever of unknown origin (eg, occult abscess, empyema, typhoid fever, etc)Two sets of cultures—one from each of two prepared sites, the second drawn after a brief time interval (30 minutes). If cultures are negative after 24 to 48 hours obtain two more sets, preferably prior to an anticipated temperature rise.The yield after four sets of cultures is minimal. A maximum of three sets per patient per day for three consecutive days is recommended.EndocarditisAcuteObtain three blood culture sets within two hours, then begin therapy.95% to 99% of acute endocarditis patients (untreated) will yield a positive in one of the first three cultures.SubacuteObtain three blood culture sets on day one, repeat if negative after 24 hours. If still negative or if the patient had prior antibiotic therapy, repeat again.Adequate sample volume despite low level bacteremia or previous therapy should result in a positive yield.Immunocompromised Host (eg, AIDS)Septicemia, fungemia mycobacteremiaObtain two sets of cultures from each of two prepared sites; consider lysis concentration technique to enhance recovery for fungi and broth systems for recovery of mycobacteria.Low levels of fungemia and mycobacteremia frequently encountered.Previous Antimicrobial TherapySepticemia, bacteremia; monitor effect of antimicrobial therapyObtain two sets of cultures from each of two prepared sites; increased volume >10 mL/set.Recovery of organisms is enhanced by dilution and increased sample volume.Interpretation of Positive Blood Cultures**Adapted from Flournoy DJ, Adkins L. Understanding the blood culture report.Am J Infect Control.1986 Feb; 14(1):41-46.Virtuallyanyorganism, including normal flora,cancause bacteremia.A negative culture result does not necessarily rule out bacteremia; false-negative results occur when pathogens fail to grow.A positive culture result does not necessarily indicate bacteremia; false-positive results occur when contaminants grow.Gram-negative bacilli, anaerobes, and fungi should be considered pathogens until proven otherwise.The most difficult interpretation problem is to determine whether an organism that is usually considered normal skin flora is a true pathogen.

Infectious Diseases

Patients with acute infection develop IgG, IgM, and IgA antibodies to fimbrial agglutinogens, and IgM and IgA antibodies are probably diagnostic. Following vaccination, IgG and IgM antibodies can be demonstrated. IgG antibodies can only be used to diagnose acute infection when paired sera are available and a rise in antibody level can be demonstrated.

Infectious Diseases

Neisseria gonorrhoeae (gonococci)is the causative agent of gonorrhea. In men, this disease generally results in anterior urethritis accompanied by purulent exudate. In women, the disease is most often found in the cervix, but the vagina and uterus may also be infected.

Infectious Diseases

C. trachomatisinfections are the leading cause of sexually transmitted diseases in the united states.C. trachomatisis known to cause cervicitis, pelvic inflammatory disease (PID), epididymitis and proctitis. It is also the most frequent cause of non-gonococcal urethritis in men. Among women, the consequences of chlamydial infections are severe if left untreated. Approximately half of chlamydial infections are asymptomatic.

Infectious Diseases

Epstein-Barr (EB) virus is a herpes group virus that is ubiquitous. It is the cause of classic infectious mononucleosis and is causally implicated in the pathogenesis of Burkitt lymphoma, some nasopharyngeal carcinomas, and rare hereditary lymphoproliferative disorders. The serologic response to EB virus includes antibody to early antigen, IgM and IgG antibodies to viral capsid antigen (VCA), and antibodies to Epstein-Barr nuclear antigen (EBNA).Although most cases of infectious mononucleosis can be diagnosed on the basis of clinical findings, blood count and morphology, and a positive test for heterophile antibody, as many as 20% may be heterophile-negative, at least at presentation (Heterophile may become positive when repeated in a few days). In some of these cases, a test for Epstein-Barr virus antibodies may be useful.The most controversial use of EBV serology is in chronic fatigue syndrome, a complaint predominantly (but not exclusively) of young to middle-aged women, characterized by long persistent debilitating fatigue and a panoply of usually mild somatic complaints. The high levels of EBV antibodies in the general population, their long persistence, and the poor correlation of antibody titers with symptoms combine to make EBV serology useless in diagnosing, following, or ruling out chronic fatigue syndrome. See table.EBV Interpretation TableInterpretationVCA-IgMVCA-IgGEBNA-IgGKey —Antibody present: (+); Antibody absent: (−)No previous infection/Susceptibility−−−Primary infection (new or recent)++−Past infection±++See comment below*+−−*Results indicate infection with EBV at some time however cannot predict the timing of the infection since antibodies to EBNA usually develop after primary infection or, alternatively, approximately 5-10% of patients with EBV never develop antibodies to EBNA.

Infectious Diseases

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Infectious Diseases

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Infectious Diseases

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Infectious Diseases

Tetanus is caused by Clostridium tetani. Immunization with Tetanus Antitoxoid is effective with boosters in immunocompetent individuals. Antibody levels > or = to 0.10 IU/mL are considered protective. However, tetanus can still occur in some individuals with such antibody levels. These results should not be used to determine the necessity to administer antitoxin when clinically indicated. For Pre and Post vaccination testing to assess normal immune response, please refer to Test Code 91424, Tetanus Antitoxoid, Pre and Post Vaccination.

Infectious Diseases, Sexual Health & STDs

Varicella-Zoster Virus (VZV) causes chicken pox and when reactivated, potentially decades later, causes shingles. Twenty percent of adults will develop shingles, a rash or blister of the skin that may cause severe pain.

Infectious Diseases

T. gondiiIgM is typically detected within a few days of infection, peaks within a few weeks, and usually falls to undetectable levels within a few months. In some patients, however,T. gondiiIgM persists for more than a year; Thus, detection ofT. gondiiIgM does not necessarily indicate recent or ongoing toxoplasmosis.

Digestive Health, Infectious Diseases

Diseases caused by human parasites remain on a worldwide basis among the principle causes of morbidity and mortality. Correct diagnosis of intestinal parasitic infection depends on proper collection, transport, detection and identification of parasites in stool specimens. Symptoms range from malaise to death. Treatment is dependent upon examining multiple stool specimens due to the erratic shed rates of some parasites.

Infectious Diseases, General Health & Wellness

Primary infection by EBV causes infectious mononucleosis, usually a self-limiting disease in children and young adults. Infection with EBV can cause lymphoproliferative disorders including tumors. VCA-IgM is typically detectable at clinical presentation, then declines to undetectable levels within a month in young children and within 3 months in other individuals.

Autoimmune & Inflammation, Infectious Diseases

CH50 is a screening test for total complement activity. Levels of complement may be depressed in genetic deficiency, liver disease, chronic glomerulonephritis, rheumatoid arthritis, hemolytic anemias, graft rejection, systemic lupus erythematosis, acute glomerulonephritis, subacute bacterial endocarditis and cryoglobulinemia. Elevated complement may be found in acute inflammatory conditions, leukemia, Hodgkin's Disease, sarcoma, and Behcet's Disease.

Digestive Health, Infectious Diseases

Giardiasis is recognized as an important human intestinal disease in most areas of the world. The causative organism, Giardia duodenalis (lamblia) is the most frequently identified protozoan parasite in stool specimens submitted to public health laboratories. This parasite has been implicated in a number of epidemics and the endemicity in the U.S., is well recognized. Acute symptoms of Giardiasis may include diarrhea, malabsorption, abdominal cramps, anorexia, nausea, weight loss, flatulence, anemia, and general weakness lasting from several weeks to several months. Chronic infections can also occur with or without an acute phase, are often associated with treatment failure and may result in recurrent symptoms. Infection with Giardia may also be asymptomatic.

Autoimmune & Inflammation, Infectious Diseases

This test can be useful for the detection of cold agglutinins in association with cold agglutinin syndrome

Infectious Diseases

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Infectious Diseases

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Infectious Diseases

Used to evaluate diphtheria immunization response. Antibody levels of ≥0.10 IU/mL are considered protective. For Pre and Post vaccination testing to assess normal immune response, please refer to test code 10680-Diphtheria Antitoxoid, Pre and Post Vaccination.

Infectious Diseases, General Health & Wellness

Primary infection by EBV causes infectious mononucleosis, usually a self-limiting disease in children and young adults. Infection with EBV can cause lymphoproliferative disorders including tumors. VCA-IgG is typically detectable at clinical presentation, and persists for life. Absence of VCA-IgG usually indicates the patient is susceptible to EBV infection.

Infectious Diseases, Respiratory Health

A positive result indicates prior exposure toMycoplasma. A single positive IgG result may be present in the absence of any clinical symptoms as specific IgG antibodies may remain elevated for up to one year after the initial infection. Recent or acute infection can only be documented by a positiveMycoplasmaIgM result and/or a significant increase in the IgG value between sera drawn two to four weeks apart. In some individuals,MycoplasmaIgG levels decline to undetectable levels after four to six months.

Infectious Diseases, Respiratory Health

Low positive results (770-950 units/mL) are presumptive evidence of acute or recent infection. It is recommended that the test be repeated on a fresh specimen one to two weeks later to assure reactivity. Specific IgM may persist for several months after initial infection or be absent during reinfection.

Infectious Diseases

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Infectious Diseases

Primary infection by EBV causes infectious mononucleosis, usually a self-limiting disease in children and young adults. Infection with EBV can cause lymphoproliferative disorders including tumors. EBNA IgG typically appears during convalescence (3-4 months after clinical presentation) and remains detectable for life. VCA-IgM positivity in the absence of EBNA IgG suggests recent, active infection.

Infectious Diseases

Rubella is an acute exanthematous viral infection of children and adults. Rash, fever and lymphadenopathy characterize the illness. While many infections are subclinical, this virus has the potential to cause fetal infection with resultant birth defects. In the absence of a current or recent infection, a demonstration of specific IgG on a serum sample is evidence of immunity to rubella. A positive rubella IgM result does not necessarily indicate current or recent infection. Without a history of exposure to rubella or symptoms consistent with rubella, the IgM result may be difficult to interpret. Rubella IgM can be false positive due to other causes (e.g., parvovirus, rheumatoid factor, cytomegalovirus). Rubella IgM may also persist for more than 12 months after vaccination or natural infection. For a serologic diagnosis of congenital rubella in the neonatal period, antibody to rubella virus should be measured in both infant and maternal sera. If IgM is detected in a newborn infants serum, it is probable that transplacental rubella infection has occurred.

Infectious Diseases, General Health & Wellness

This panel provides presumptive evidence of immunity to measles, mumps, and rubella for purposes of routine vaccination, for students at post-high school educational institutions, and for international travelers.

Infectious Diseases

Antibody levels above the reference range are highly suggestive of recent infection or vaccination.

Sexual Health & STDs, Infectious Diseases

Identification ofTreponema pallidumantibodies may aid in the diagnosis of syphilis.

Infectious Diseases, Respiratory Health

This test allows rapid diagnosis of the presence of respiratory syncytial virus. It avoids the necessity of obtaining acute and convalescent specimens over a two-week period. It may be particularly useful in children younger than six months old, whose antibody response to infection may not be diagnostic.

Infectious Diseases

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Infectious Diseases

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Infectious Diseases

ADNase B antibodies react against the exoenzyme desoxyribonuclease B produced by streptococci. The detection of these antibodies provides evidence of an existing or past streptococcal infection (rheumatic fever, scarlet fever, tonsillitis, glomerulonephritis, and others). The antibody reaction against streptococcal DNase B starts later than the antibody production against streptolysin O, but it can then be detected on a greater percentage of patients.1An increase in the antistreptolysin concentration rarely occurs with skin infections, while a rise in the ADNase B titer can be observed.1-3

Infectious Diseases

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Autoimmune & Inflammation, Infectious Diseases

Lysozyme in the serum is primarily due to the degradation of granulocytes and monocytes and its concentration reflects the turnover of these cells. Increases are seen in benign and malignant processes. Serum lysozyme is elevated in patients with acute or chronic granulocytic or monocytic leukemias and levels decrease with successful treatment. Conversely, patients with lymphocytic leukemia may have depressed plasma lysozyme levels.

Infectious Diseases

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Infectious Diseases, Autoimmune & Inflammation

Documents recentstreptococcalinfection.

Infectious Diseases

Lyme disease is transmitted by a tick vector carryingBorreliaburgdorferi. Immunoblot testing qualitatively examines, with high specificity, antibodies in a patient's specimen. Immunoblot testing is appropriate for confirming a detected EIA or IFA test result.

Infectious Diseases

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Digestive Health, Infectious Diseases

The importance ofHelicobacter pyloriin gastrointestinal diseases has increased greatly since Marshall and Warren described the presence of Campylobacter-like organisms in the antral mucosa of patients with histological evidence of antrum gastritis and peptic ulcers, especially duodenal ulcers. The strong correlation between the presence ofH. pyloriwithin histologically confirmed gastritis, peptic ulcer disease and gastric carcinoma and lymphoma, as well as disease resolution afterH. pylorieradication, indicates a causative relationship. The ecological niche in humans appears to be restricted to the stomach and duodenum. Patients who harbor the organism are divided into two basic groups. The first are those who are said to be "colonized". These patients have the organism, yet have no signs of gastrointestinal disease. Those with gastrointestinal symptoms and a positiveH. pyloriantigen test are considered to be infected.

Autoimmune & Inflammation, Infectious Diseases

This panel separately reports CD4+ T cells (CD4) and CD8+ T cells (CD8) in the blood, as well as a calculated CD4/CD8 ratio. This panel may provide information of the immune status of individuals living with HIV. It can be used to help establish baseline values and track antiretroviral (ARV)-related treatment progress. It can also be used to evaluate helper and suppressor cell immune status in individuals with other immunodeficiency diseases.The CD4 count is the most valuable indicator of immune status in HIV-infected individuals. It can help determine the need for prophylaxis for opportunistic infections and the urgency of ARV initiation. The CD8 count reflects the level of immune activation in response to HIV. In the early stages of infection, CD4 levels and the CD4/CD8 ratio typically decline after seroconversion occurs. However, after seroconversion, CD8 cells increase in an attempt to mount a response against HIV. In ARV-treated patients with controlled viral load, CD8 counts. Post-therapy, persistently elevated CD8 counts have been linked to increased risk of non--AIDS-defining diseases, independent of CD4 count, including cardiovascular, renal, respiratory, metabolic diseases, and cancer [1-3].This panel can be used to establish baseline CD4 and CD8 levels, as well as percentages and ratios, which help determine how long the virus has been present in the blood and the overall prognosis. During ARV treatment, this panel can help assess CD4 recovery and CD8 response to treatment [1,2].During the first 2 years of ARV therapy, The National Institutes of Health recommends testing CD4 every 3 to 6 months. Patients who develop viremia while on therapy or whose CD4 count stays below 300 cells/µL. should also have their CD4 levels tested every 3 to 6 months. After 2 years of ARV therapy, with consistently suppressed viral load and a CD4 count of 300 to 500 cells/µL, CD4 counts should be tested every 12 months. CD4 testing should also be conducted if therapy fails. Note that CD4 testing is optional when CD4 counts are >500 cells/µL [1].References1. Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents. Department of Health and Human Services.https://aidsinfo.nih.gov/contentfiles/lvguidelines/adultandadolescentgl.pdf. Updated July 10, 2019. Accessed November 10, 2019.2. Warren JA, et al.Front Immunol. 2019;10:291. Published February 26, 2019. doi:10.3389/fimmu.2019.002913. Cao W, et al.J Int AIDS Soc. 2016;19:20697. Published March 3, 2016. doi: 10.7448/IAS.19.1.20697

COVID-19, Infectious Diseases

Current literature suggests that detectable antibodies against SARS-CoV-2 develop approximately 8 to 11 days following onset of symptoms. Correlation with epidemiologic risk factors and other clinical and laboratory findings is recommended. A positive serologic result is not diagnostic but indicates that an individual has likely been infected with SARS-CoV-2 and produced an immune response to the virus. It is not known at this time whether detectable antibody correlates with immunity. A negative serologic result indicates that an individual has not developed detectable antibodies at the time of testing. While contingent on a variety of factors, this could be due to testing too early in the course of infection, the absence of exposure to the virus, or the lack of adequate immune response, which can be due to conditions or treatments that suppress immune function.FDA-authorized Fact sheets for patients and providers can be accessed at the following link:https://www.fda.gov/medical-devices/emergency-situations-medical-devices/emergency-use-authorizations#covid19ivd.

Infectious Diseases

This antibody panel helps diagnose infections withBartonella henselaeandBartonella quintana.This panel includes IgM and IgG antibodies with reflexes to titers for positive results.B henselaecauses cat scratch disease, a self-limiting bacterial infection transmitted via exposure to cats or cat fleas.B quintanacauses trench fever, a febrile bacteremic illness transmitted via body lice.B henselaeandB quintanaare the 2Bartonellaspecies that most frequently cause blood culture-negative endocarditis. In immunocompromised individuals, infections withB henselaeand B quintanamay present as bacillary angiomatosis, a vasculoproliferative disease of the skin [1-4].Because of the fastidious nature ofB henselaeand B quintana, recovery of these bacteria is rarely successful, especially from blood. Serology is commonly used for diagnosingBartonellainfections [1,3]. Confirmation of recent or current infection with eitherB henselaeorB quintanamay require testing of serial specimens to demonstrate a 4-fold increase of IgG titers or the presence of IgM. AB henselaeorB quintanaIgG titer of 1:800 has been proposed as a major criterion for diagnosingBartonellaendocarditis [4].IgG cross-reactivity betweenB henselaeandB quintanaoften occurs [1,3]. Qualitative real-time polymerase chain reaction is a highly specific and sensitive method to detect the presence ofBartonellaspecies DNA in clinical specimens and can differentiate betweenB henselaeandB quintana.The results of this test should be interpreted in the context of pertinent clinical history and physical examination findings.References1. Dumler JS, et al.Bartonella. In: Carroll KC, et al, eds.Manual of Clinical Microbiology.12th ed. ASM Press; 2019.https://www.clinmicronow.org/doi/book/10.1128/9781683670438.MCM.ch502. Centers for Disease Control and Prevention.Bartonellainfection (cat scratch disease, trench fever, and Carrion's disease). Last reviewed December 18, 2019. Accessed January 28, 2022.https://www.cdc.gov/bartonella/clinicians/index.html3. Miller JM, et al.Clin Infect Dis. 2018;67(6):813-816.4. Okaro U, et al.Clin Microbiol Rev. 2017;30(3):709-746.

Infectious Diseases

A positive result indicates prior exposure toMycoplasma. A single positive IgG result may be present in the absence of any clinical symptoms as specific IgG antibodies may remain elevated long after initial infection. Recent or acute infection can only be documented by a positiveMycoplasmaIgM result and/or a significant increase in the IgG value between sera drawn two to four weeks apart. Specific IgM antibodies may persist for several months after infection or be absent during reinfection.

Infectious Diseases

This test helps detectMycoplasma pneumoniaeinfections. Respiratory tract infections including community-acquired pneumonia are common reasons for testing forM pneumoniae, especially in children [3,4].Clinical presentations ofM pneumoniaeinfection are generally mild, but can vary widely across individuals, and are most often characterized by tracheobronchitis with upper respiratory tract symptoms. Approximately one-third of people withM pneumoniaeinfection develop pneumonia that was previously considered "atypical." Extrapulmonary complications may include encephalitis, hemolytic anemia, renal dysfunction, gastrointestinal complaints, erythema multiforme, and Stevens-Johnson syndrome [1,2].M pneumoniaeinfection is diagnosed by culture, serology, or nucleic acid amplification tests. Serologic tests may be useful when the possibility ofMycoplasmainfection is high. A positive IgG result indicates previous or recent infection. Testing children who have suspected community-acquired pneumonia forM pneumoniaemay help guide antibiotic selection [3,4].Clinical false-negative results for IgG- and IgM-based serologic tests can occur due to compromised immunity, testing before an antibody response has started, or the presence of interfering substances in host serum.Real-time polymerase chain reaction testing forM pneumoniaeDNA is more sensitive than serology testing and can provide timely results to inform patient management [2]. IgA antibodies toM pneumoniaeappear early; testing IgA antibodies may aid in identifying acute infection [1].The results of this test should be interpreted in the context of pertinent clinical history and physical examination findings.References1. Waites KB, et al.MycoplasmaandUreaplasma. In: Carroll KC, et al, eds.Manual of Clinical Microbiology.12th ed. ASM Press; 2019.https://www.clinmicronow.org/doi/book/10.1128/9781683670438.MCM.ch642. Centers for Disease Control and Prevention.Mycoplasma pneumoniaeInfections. Last reviewed June 5, 2020. Accessed January 27, 2022.https://www.cdc.gov/pneumonia/atypical/mycoplasma/hcp/index.html3. Miller JM, et al.Clin Infect Dis. 2018;67(6):813-816.4. Bradley JS, et al.Clin Infect Dis. 2011;53(7):617-630.

Infectious Diseases, Liver & Kidney Health

Hepatitis A virus (HAV) is a picovirus primarily transmitted via the fecal-oral route. HAV replicates in the liver and is shed in high concentrations in feces from 2-3 weeks before to 1 week after the onset of clinical illness. IgM antibody develops within a week of symptom onset, peaks around three months, and is usually no longer detectable after six months. The presence of IgM antibody to HAV is diagnostic of acute HAV infection.Hepatitis B surface antigen (HBsAg) is a distinctive serological marker of acute or chronic hepatitis B infection. HBsAg is the first antigen to appear following infection with HBV and is generally detected 1-10 weeks after the onset of clinical symptoms. HBsAg assays are routinely used to diagnose suspected HBV infection and monitor the status of infected individuals to determine whether the infection has resolved or the patient has become a chronic carrier of the virus. In patients that recover from HBV infection, HBsAg is undetectable 3-5 months after the onset of infection. In patients with chronic infection, HBsAg remains detectable for life.Anti-HBc IgM increases rapidly, peaks during the acute infection stage of HBV infection, and then falls to a relatively low level as the patient recovers or becomes a chronic carrier. Anti-HBc IgM is useful in the diagnosis of acute HBV infection even when HBsAg concentrations are below the sensitivity of the diagnostic assay.Detection of both HCV antibody and HCV RNA indicates current HCV infection. Detection of HCV antibody in the absence of HCV RNA is consistent with the absence of current HCV infection. Repeat HCV RNA testing is recommended if the person tested is suspected to have had HCV exposure within the past 6 months or has clinical evidence of HCV disease.

Infectious Diseases

IgM antibodies are detectable two weeks after exposure. IgG antibody production usually occurs 18 to 24 days after exposure. The presence of IgM antibodies to parvovirus B19 provide definite evidence of recent infection.

Infectious Diseases, Blood Disorders

Parvovirus B19 is also known as Fifth Disease. It primarily affects children and causes a rash on the face, trunk, and limbs. Joint pain and swelling is more common in adults. Although one-fifth of those affected have only mild disease, patients with sickle cell anemia or similar types of chronic anemia can suffer from acute anemia. Infection during pregnancy can lead to complications.

Infectious Diseases, General Health & Wellness

Offered as part of multiple lab tests

Infectious Diseases

Measles, also known as Rubeola, causes fever, irritability, respiratory illness, and the characteristic skin rash. Immunization has greatly diminished the incidence of measles. The presence of IgG is consistent with immunity or prior exposure. IgM is consistent with current or recent infection. IgM tests can generate false positive results and low levels of IgM can persist for longer than 12 months.

Autoimmune & Inflammation, Infectious Diseases

C3a desArg is a cleavage product of C3 complement component activation. Elevated levels of C3a have been reported in patients with acute lyme disease, acute pancreatitis, systemic lupus erythematosus, and adult respiratory distress syndrome.

Infectious Diseases

This test is a blood-based interferon-gamma release assay (IGRA) used as an aid in the diagnosis ofMycobacterium tuberculosisinfection. It is an immune response-based, indirect test forM tuberculosisinfection (including disease) and is intended for use in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations. Additional testing is needed to determine if a person who has tested positive has latent tuberculosis (TB) infection or TB disease.This in vitro diagnostic test uses a peptide cocktail simulating ESAT-6, CFP-10, and TB7.7 proteins to stimulate cells in heparinized whole blood. Detection of interferon-γ (IFN-γ) by ELISA is used to identify in vitro responses to those peptide antigens that are associated withMycobacterium tuberculosisinfection.For the four-tube QFT-Plus testing option, see test code #36971.Guidelines recommend testing for individuals who 1) have been exposed to a person with latent or active TB, including the general population and healthcare workers; 2) are from TB-endemic countries, which include most countries in Latin America, the Caribbean, Africa, Asia, and Eastern Europe, and Russia; 3) work in high-risk settings, such as correctional facilities, long-term care (LTC) facilities, nursing homes, and homeless shelters; or 4) have HIV or have an injection drug substance use disorder [1].All of these individuals can be tested with either a traditional tuberculin skin test (TST) or an IGRA. However, the American Thoracic Society (ATS), the Infectious Disease Society of America (IDSA), and the Centers for Disease Control and Prevention (CDC) jointly prefer an IGRA test for individuals who have been vaccinated against bacillus Calmette-Guérin (BCG) or are not likely to return for the follow-up portion of the TST (and in both cases are at least 5 years old and likely to have TB infection and are at low or moderate risk of disease progression, or in whom it has been determined that TB testing is necessary [1]. The QuantiFERON-TB Gold test has specificity >99% in low-risk individuals and sensitivity of 92% in individuals with active disease [2].In contrast to the TST, IGRA testing for TB requires only 1 patient visit (instead of 2). Also, IGRAs are not associated with the booster phenomenon, in which previously infected individuals generate a false-positive on a TST. In addition, prior BCG vaccination does not generate a false-positive result. Note that for children aged 2 and above, either TST or IGRA can be used [3,4]The CDC does not recommend dual testing with both a TST and an IGRA, unless the goal is to confirm a positive result, or when a high-risk individual’s test results are negative and there is clinical suspicion of TB. In this clinical situation, dual testing is used for confirmatory purposes [4].For more information about TST versus IGRA testing, please visit theQuantiFERON®-TB Gold FAQspage.Note that when using QuantiFERON®-TB Gold Plus, blood samples must be processed within 16 to 48 hours after collection while white blood cells are still viable.References1. Lewinsohn DM, et al.Clin Inf Dis. 2017;64:111-115.2. QuantiFERON®-TB Gold Elisa [package insert]. Germantown, MD: Qiagen; August 2016.3. American Academy of Pediatrics. In: Kimberlin DW, et al, eds.Red Book: 2018 Report of the Committee on Infectious Diseases, 31st ed. Itasca, IL: American Academy of Pediatrics;2018: 829-853.4. CDC. Fast facts: Interferon-gamma release assays (IGRAs)-blood tests for TB infection. Published November 2011.https://www.cdc.gov/tb/publications/factsheets/testing/igra.htm

Infectious Diseases

Used to evaluate diphtheria immunization response. Antibody levels of > or = to 0.10 IU/mL are considered protective. For Pre and Post vaccination testing to assess normal immune response, please refer to Test Code 10680, Diphtheria Antitoxoid, Pre and Post Vaccination.Tetanus is caused by Clostridium tetani. Immunization with Tetanus Antitoxoid is effective with boosters in immunocompetent individuals. Antibody levels of > or = to 0.10 IU/mL are considered protective. However, tetanus can still occur in some individuals with such antibody levels. These results should not be used to determine the necessity to administer antitoxin when clinically indicated. For Pre and Post vaccination testing to assess normal immune response, please refer to Test Code 91424, Tetanus Antitoxoid, Pre and Post Vaccination.

Infectious Diseases, Digestive Health

Offered as part of multiple lab tests

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Haemophilus influenzaeis a gram-negative bacteria that is present in approximately three-quarters of children and adults. In infants and young children,haemophilus influenzae, especially type B, may cause bacteremias and meningitis. In children and older individualshaemophilus influenzaemay cause respiratory tract infections.

Infectious Diseases, General Health & Wellness

Primary infection by EBV causes infectious mononucleosis, usually a self-limiting disease in children and young adults. Infection with EBV can cause lymphoproliferative disorders including tumors. VCA-IgM is typically detectable at clinical presentation, then declines to undetectable levels within a month in young children and within 3 months in other individuals. VCA-IgG is typically detectable at clinical presentation, and persists for life. EBNA IgG typically appears during convalescence (3-4 months after clinical presentation) and remains detectable for life.

Infectious Diseases, Sexual Health & STDs

Herpes Simplex Virus (HSV) is responsible for several clinically significant human viral diseases, with severity ranging from inapparent to fatal. Clinical manifestations include genital tract infections, neonatal herpes, meningoencephalitis, keratoconjunctivitis, and gingivostomatitis. There are two HSV serotypes that are closely related antigenically. HSV type 2 is more commonly associated with genital tract and neonatal infections, while HSV type 1 is more commonly associated with infections of non-genital sites. Specific typing is not usually required for diagnosis or treatment. The mean time to seroconversion using the type specific assay is 25 days. The performance of this assay has not been established for use in a pediatric population, for neonatal screening, or for testing of immunocompromised patients.

Infectious Diseases, Sexual Health & STDs

Offered as part of multiple lab tests

Infectious Diseases, Sexual Health & STDs

In patients who are immunocompromised, CMV may cause disseminated, severe disease. CMV is also the most common cause of congenital viral infection in humans. Quantitative PCR methods may be useful in monitoring CMV replication in immunosuppressed patients. This is a quantitative molecular test, with a linear range of 34.5-10,000,000 IU/mL (1.54-7.00 log IU/mL).

Infectious Diseases, Digestive Health

During the last several years, increased rates ofC difficileinfection have been reported, noting more severe disease and an associated increase in mortality.C difficileinfection remains a disease mostly associated with health care (at least 80%), with the elderly remaining at greatest risk. More disease has been reported in traditionally "low-risk" individuals, such as healthy persons in the community and peripartum women. Severe disease outbreaks ofC difficileinfection in health care facilities have been attributed to the emergence of a hypervirulent epidemic strain, known by its names—assigned by various typing schemes—as restriction enzyme analysis type BI, North American Pulsed Field type 1 (NAP1), or PCR ribotype 027. BI/NAP1/027 has spread widely, and it appears more virulent due to its increased production of toxins A and B and its production of an additional toxin known as binary toxin. This strain is also believed to produce more spores, leading to enhanced persistence in the environment.

Infectious Diseases

⁠⁠⁠⁠⁠⁠⁠What is the RFFIT??The acronym RFFIT stands for Rapid Fluorescent Focus Inhibition Test. The test measures the ability of antibodies that may be present in a sample to neutralize and block rabies virus from infecting the cells used in the test. These antibodies are called rabies virus neutralizing antibodies (RVNA). In the test, serum (the non-cellular portion of a blood sample) is first diluted fivefold (1 part serum in 4 parts diluent). Further (serial fivefold) dilutions are performed, each of which contain less and less of the sample. The serum dilutions are mixed with a standard amount of live rabies virus and incubated. If RVNA are present in the sample, they will bind to the virus. Tissue culture cells are then added and incubated with the test sample and virus. Whatever rabies virus that may not have been neutralized by the antibody in the sample will then infect the cells. These foci of infection in the cells can then be seen under the fluorescent microscope. If there are a lot of infected cells, there is very little antibody; conversely, if antibodies are high, the cells will have very little evidence of infection. The endpoint titer is calculated from the percent of virus-infected areas observed within the wells containing the various dilutions of the sample on the slide.What does your result tell you?The RFFIT result can be reported in either a titer which is a ratio (e.g., 1:50) or as a standardized concentration represented as international units (IU) per mL of serum (e.g., 0.5 IU/mL). The IU value is calculated from the titer by comparing it against a standard reference serum. We use the following formula: sample titer divided by the reference serum titer, multiplied by the IU/mL value of the reference serum.Because the RFFIT test is a biological system using live cells, infectious virus, and antibodies, the reference serum can vary in titer level for each batch of testing (within an established acceptable range). Therefore the calculation of IU/mL depends on the titer of the reference serum measured in the batch tested. In general, you can take the titer value divided by 100 to get a rough estimate of the IU/mL value. To obtain the exact value you must use the calculation with the reference serum titer value that resulted from that batch of tests.According to World Health Organization guidelines, a rabies antibody level of greater than or equal to 0.5 IU/mL demonstrates an adequate response to vaccination (1). If the level falls below this value, a booster dose of rabies vaccine may be recommended for people who are at frequent risk of rabies virus exposure. In contrast, the ACIP guidelines state that evidence of complete neutralization at a serum dilution of 1:5 in RFFIT testing (corresponding to 0.1-0.2 IU/mL in our laboratory) is considered an adequate response to rabies vaccination (2). The lowest antibody level that can be accurately and precisely measured by the RFFIT in our laboratory is 0.1 IU/mL; below this level, there is uncertainty as to the specificity of the result. Because the ACIP level is close to the assay threshold, the level of 0.5 IU/mL is more conservative for guiding human vaccination decisions and applicable in most situations.Points that should be considered as to whether a person should receive a booster dose of rabies vaccine when their antibody level falls below 0.5 IU/mL are:-Anticipated risk of exposure (i.e., routinely handling sick animals or rabies reservoir species in enzootic areas)-Length of time until the next antibody measurement-Previous rabies antibody levels and the probability of decay to low or undetectable levels in the intervening period-Individual health status (consider immunocompromising conditions or a history of poor vaccine response)-Timely access to vaccine and administration should a potential exposure occurFor further information, see Level of rabies protection.

Infectious Diseases

Lyme disease is caused by a bacteriumborrelia burgdorferiand is transmitted by ticks. A screening test with high sensitivity is used as the first step in the CDC recommended algorithm. Immunoblot testing qualitatively examines, with high specificity, antibodies in a patient's specimen. Immunoblot testing is appropriate for confirming a detected screening result.

Infectious Diseases, Liver & Kidney Health

HAV Serology Interpretation: Key - Analyte present: + Analyte absent: - Test not indicated: TNIInterpretationHAV Ab, TotalHAV Ab, IgMSusceptible/no indication of infection-TNIPreviously vaccinated against or infected with HAV+-Acute infection++HBV Serology Interpretation: Key - Analyte present: + Analyte absent: - Test not indicated: TNIInterpretationHBsAganti-HBsanti-HBcIgM anti-HBc* Multiple possibilities: resolved infection (most common); false-positive anti-HBc (susceptible); "low-level" chronic infection; resolving acute infection.Susceptible/no evidence of infection---TNIImmune due to natural resolved infection-++TNIImmune due to vaccination-+-TNIAcute infection+-++Chronic infection+-+-Interpretation unclear*--+±HCV Serology Interpretation: Key - Analyte present: + Analyte absent: - Test not indicated: TNIInterpretationHCV AbHCV RNA, NAA*For persons who might have been exposed to HCV within the past 6 months, testing for HCV RNA or follow-up testing for HCV antibody should be performed. For persons who are immunocompromised, testing for HCV RNA should be performed.**Repeat HCV-RNA testing if the person tested is suspected to have had HCV exposure within the past 6 months or has clinical evidence of HCV disease.No HCV antibody detected, no indication of infection*-TNIHCV antibody detected but no evidence of current infection**+-HCV antibody and viral RNA detected consistent with current infection++

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

This test is intended for the qualitative detection of antibodies against Hepatitis E virus (HEV). HEV causes acute viral hepatitis and liver injury worldwide, although it is not commonly acquired in the United States. Diagnosis of acute infection can be achieved through the detection of IgM, whereas IgG may represent remote or past exposure. This test does not detect antibodies against other hepatitis-causing viruses, including Hepatitis A, B, or C.HEV is transmitted via the fecal-oral route, most commonly by consumption of contaminated water or undercooked meat. Signs and symptoms of HEV are similar to other causes of acute viral hepatitis and may include fever, fatigue, nausea, vomiting, jaundice, and dark urine. The disease can be mild and self-limiting, and most individuals recover from illness. Immunocompromised individuals, those with underlying liver conditions, and pregnant women are at increased risk for severe disease, including fulminant hepatitis. Testing is recommended in patients with viral hepatitis symptoms who have traveled to an endemic or outbreak area and/or have tested negative for other etiologies (Hepatitis A, Hepatitis B, Hepatitis C, other hepatotropic viruses, and causes of acute liver injury).Antibodies against HEV can typically be detected within 3-4 weeks after exposure. Anti-IgM declines during early convalescence and may be negative a few months post- exposure while anti-IgG can persist for years. Results should be correlated with patient risk factors and signs and symptoms consistent with Hepatitis E. False positive results can occur in low prevalence populations. False negative results can occur early during infection. If there is a high clinical suspicion for HEV, repeat testing can be performed in 2-4 weeks.References1. Q&As for Health Professionals, Viral Hepatitis, Centers for Disease Control and Prevention.https://www.cdc.gov/hepatitis/hev/hevfaq.htmPage last reviewed: September 15, 2020.2. Hepatitis E, World Health Organization.https://www.who.int/news-room/fact-sheets/detail/hepatitis-eLast updated: 20 July 2023.3. Aggarwal, R. et al. Diagnosis of hepatitis E. Nat Rev Gastroenterol Hepatol. 2013 Jan;10(1):24-33.4. American Academy of Pediatrics, Red Book 2018-2021. Report of the Committee of Infectious Diseases, 31st Edition.

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Published data for the median sensitivity and specificity for serum specimens are 100% and 99.5%, respectively. False-positive results due to the presence of rheumatoid factor havenotbeen noted with the cryptococcal antigen lateral flow immunochromatographic assay. A negative test does not preclude diagnosis ofCryptococcusinfection, particularly if only a single specimen has been tested and the patient shows symptoms consistent with cryptococcosis.

Infectious Diseases

The encapsulated soil yeastCryptococcusneoformans causesCryptococcosis. Pulmonary infection is acquired by inhalation of the organism and is usually subclinical in the immunocompetent host. Dissemination may occur in an immunocompromised patient, often to the meninges.

Infectious Diseases

Infection byCoccidioides immitiscan produce a spectrum of disease, with most patients being asymptomatic and some developing disseminated disease, including pneumonia and meningitis.

Infectious Diseases

This sensitive procedure is recommended for vaccine response testing and type-specific serodiagnosis of recent poliovirus infection. It can also serve as an aid for diagnosing immune deficiency disorders.

Digestive Health, Infectious Diseases

Helicobacter pyloriis a gram-negative microaerophilic curved bacillus with an affinity for human gastric mucosa.H. pylorihas been identified as an important pathogen in the upper GI tract. The casual relationship betweenH. pyloriand chronic active gastritis, duodenal ulcers, and gastric ulcers has been well documented. PyloPlus® UBT breath tests provide a non-invasive and non-hazardous method for detecting currentH. pyloriinfection using urea breath analysis.

Autoimmune & Inflammation, Infectious Diseases

IgD (molecular weight 185 kD) is one of the 5 classes of human immunoglobulins. IgD accounts for less than 1% of the total plasma immunoglobulins. Very high serum IgD concentrations can be found in multiple myeloma patients. Raised levels are also found in hyperimmunoglobulinemia IgD syndrome (HIDS).

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Dengue hemorrhagic fever and Dengue shock syndrome are caused by infection of the RNA flavivirus transmitted by a mosquito vector. Paired acute and convalescent specimens that exhibit a significant change in titer are useful to confirm clinical diagnosis of infection.

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases, Sexual Health & STDs

This test is used for detection of Varicella-Zoster Virus (VZV) DNA in spectrum of clinical samples in individuals suspected or presenting with signs and symptoms of clinical VZV infection. Qualitative VZV PCR results can aid in diagnosis of cutaneous, subcutaneous, and visceral varicella.VZV is a member of the Herpesviridae family that causes two distinct clinical diseases in the infected individual. Varicella, or more commonly chickenpox, is the primary infection and is characterized by a generalized exanthematous rash. After primary infection, VZV characteristically becomes latent. Reactivation of the virus results in herpes zoster, or shingles, which is characterized by a vesicular rash limited to single dermatomes and is often associated with pain and paresthesia. Noncutaneous sites of VZV involvement after chickenpox or reactivation most frequently involve the central nervous system (CNS) and are manifested as acute cerebellar ataxia, encephalitis, meningitis, transverse myelitis, or Reye syndrome. Varicella pneumonitis is a serious complication of chickenpox that may be manifested as tachypnea, cough, dyspnea, and fever. VZV infection in immunocompromised individuals often leads to progressive disease state with involvement of multiple organs, including the lungs, liver, eyes, and central nervous system.This assay detects the VZV DNA in skin lesions, cerebro- spinal fluid (CSF), respiratory and eye specimens and whole blood. Detection of VZV DNA in CSF usually indicates active, not latent, infection. Detection of VZV DNA in appropriate clinical specimens permits rapid and sensitive patient testing.

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

This test is intended for the qualitative detection of Borrelia DNA in whole blood, CSF, synovial fluid, or ticks.Borreliaare spirochetes and are commonly classified into two categories: those that cause Lyme disease(Lyme borreliosis)and those that cause relapsing fever. This test detects species in both categories.Borrelia are typically transmitted to humans via the bite of an infected tick, including hard-bodied ticks of the generaAmblyommaandIxodesand soft-bodied ticks of the generaOrnithodoros.Lyme disease, the most common tick-borne infection in the United States, is marked by three stages: 1) local infection, which can include an erythema migrans or "bull's eye" skin lesion and/or flulike symptoms; 2) disseminated infection, which is typically marked by cardiac, neurological and/or skin manifestations; and 3) persistent infection, which can include Stage 2 manifestations as well as rheumatological involvement, most commonly joint pain.Relapsing fever is marked by febrile periods lasting about three days that alternate with afebrile periods include muscle and joint pain, headache, vomiting and dizziness.Diagnosis of Borrelia infections is normally based on clinical findings and serological assays. PCR testing can serve as an adjunct to serology, especially during the early stages of infection before antibodies have developed.

Infectious Diseases, Autoimmune & Inflammation

PCT is the prohormone of the hormone calcitonin, but PCT and calcitonin are distinct proteins. Calcitonin is exclusively produced by C-cells of the thyroid gland in response to hormonal stimuli, whereas PCT can be produced by several cell types and many organs in response to proinflammatory stimuli, in particular by bacterial products.1In healthy people, plasma PCT concentrations are found to be below 0.1 μg/L.2Depending on the clinical background, a PCT concentration above 0.1 μg/L can indicate clinically relevant bacterial infection, requiring antibiotic treatment.3PCT levels rise rapidly (within 6 to 12 hours) after a bacterial infectious insult with systemic consequences. The magnitude of the increase in PCT concentration correlates with the severity of the bacterial infection.4At a PCT concentration >0.5 μg/L, a patient should be considered at risk of developing severe sepsis or septic shock.5,6On the other hand, the relief of the septic infection is accompanied by a decrease in the PCT concentration which returns to normal with a half-life of 24 hours,7,8(ie, the continuous decline of PCT is indicative of effective source control measures and has been implicated in the safe deëscalation of antibiotic therapy).9,10Data support the following interpretative risk assessment criteria11,12,13:PCT > 2 ng/mL: A PCT level above 2.0 ng/mL on the first day of ICU admission is associated with a high risk for progression to severe sepsis and/or septic shock.PCT < 0.5 ng/mL: A PCT level below 0.5 ng/mL on the first day of ICU admission is associated with a low risk for progression to severe sepsis and/or septic shock.Note: Concentrations < 0.5 ng/mL do not exclude an infection, on account of localized infections (without systemic signs) which can be associated with such low concentrations, or a systemic infection in its initial stages (< 6 hours).Furthermore, increased procalcitonin can occur without infection. PCT concentrations between 0.5 and 2.0 ng/mL should be interpreted taking into account the patient's history. It is recommended to retest PCT within 6-24 hours if any concentrations < 2 ng/mL are obtained.The change of PCT concentration over time (Delta PCT) provides prognostic information about the risk of mortality14within 28 days for patients diagnosed with severe sepsis or septic shock coming from the emergency department, ICU, other medical wards, or directly from outside the hospital. Data support the use of PCT determinations from the day severe sepsis or septic shock is first diagnosed (Day 0) or the day thereafter (Day 1) and the fourth day after diagnosis (Day 4) for the classification of patients into higher and lower risk for mortality within 28 days. The Delta PCT is calculated in the manufacturer's package insert for the Elecsys BRAHMS PCT11as:The change in PCT (Day 0 value minus Day 4 value) divided by the Day 0 value, all multiplied by 100%.This calculated result is interpreted as follows:Delta PCT ≤ 80 %: A decrease of PCT levels below or equal to 80 % defines a positive ΔPCT test result representing a higher risk for 28-day all-cause mortality of patients diagnosed with severe sepsis or septic shock.Delta PCT > 80 %: A decrease of PCT levels of more than 80 % defines a negative ΔPCT result representing a lower risk for 28-day, all-cause mortality of patients diagnosed with severe sepsis or septic shock.Notes:• If Day 0 result is not available, Day 1 result may be used.• If more than one PCT value is available on Day 0 (or Day 1), enter the highest value.• If more than one PCT value is available on Day 4, enter the most recent value.

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases, Respiratory Health

Offered as part of multiple lab tests

Sexual Health & STDs, Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Infection with EBV is common and is generally subclinical or presents as a self-limited illness. Reactivation of latent EBV in an immunocompromised person can lead to more serious results, including lymphoproliferative disorders or neurological disease. PCR methods may be useful in identifying EBV in a variety of clinical specimens.

Autoimmune & Inflammation, Infectious Diseases

Primary immunodeficiencies result from congenital defects of the immune system. Acquired immunodeficiency syndrome (AIDS) results from infection with the HIV-1 retrovirus. The purpose of flow cytometric enumeration is to determine whether select lymphocyte subsets are reduced or absent in order to support the diagnosis of numeric cellular immunodeficiency rather than immunodeficiency due to cellular dysfunction.HIV-1 infection results in a decrease of CD4 T cells, an increase of CD8 T cells, a decrease in the CD4:CD8 ratio, and a progressive destruction of immune function. In HIV-1 seropositive patients, enumeration of CD4 T cells may be used for prognostic purposes and to monitor disease progression and antiretroviral therapy.

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

Offered as part of multiple lab tests

Infectious Diseases

BartonellaDNA PCR is a highly specific and sensitive method to detect the presence ofBartonellaspecies DNA in clinical specimens. This assay can differentiate betweenBartonella henselaeandBartonellaquintana. The diagnosis ofBartonellainfection should not rely solely on the result of a PCR assay. A negative PCR result indicates only the absence ofBartonellaspecies DNA in the sample tested and does not exclude the diagnosis of the disease. Patients with a positive PCR result should be evaluated with other tests to further establish the diagnosis of the disease. A positive result should be considered in conjunction with clinical presentation and additional established clinical tests.

Autoimmune & Inflammation, Infectious Diseases

Offered as part of multiple lab tests