Challenges of Rabies Serology: Defining Context of Interpretation.

The case fatality rate of rabies, nearly 100%, is one of the most unique characteristic of this ancient virus infection. The crucial role rabies virus neutralizing antibody plays in protection is both well established and explanation of why rabies serology is important. Various laboratory methods can and have been used but serum neutralization methods have long been the gold standard due to the ability to measure function (neutralization), however these methods can be difficult to perform for several reasons. Assays such as enzyme linked absorbance assays (ELISA), indirect fluorescence antibody (IFA) and more recently lateral flow methods are in use. Interpretation of results can be problematic, not only between methods but also due to modifications of the same method that can lead to misinterpretations. A common assumption in review of laboratory test results is that different methods for the same component produce comparable results under all conditions or circumstances. Assumptions and misinterpretations provide the potential for detrimental decisions, ranging from regulatory to clinically related, and most importantly what 'level' is protective. Review of the common challenges in performance and interpretation of rabies serology and specific examples illuminate critical issues to consider when reviewing and applying results of rabies serological testing.

Is the Diagnosis of Celiac Disease Possible Without Intestinal Biopsy?

BACKGROUND: Coeliac disease is defined as a state of immune-mediated hyper-responsiveness to dietary gluten from wheat, barley, or rye in genetically predisposed individuals that results in tissue damage. The diagnosis is made by microscopic examination of a small intestinal biopsy, although serological testing for antibodies against tissue transglutaminase and deamidated gliadin peptide can be of great advantage. It has been suggested that duodenal biopsy can be avoided in patients with high levels of the tissue transglutaminase antibody, since a relationship has been found to be present between tissue transglutaminase antibody titres and coeliac disease. AIMS: To study the correlation between tissue transglutaminase titre and small intestinal biopsy findings in patients with coeliac disease. STUDY DESIGN: Diagnostic accuracy study. METHODS: Ninety-five cases of patients diagnosed with coeliac disease and with positive serum tissue transglutaminase titres were retrieved from the Jordan University Hospital archives between December 2014 and December 2015. All the cases were classified according to the Marsh classification. RESULTS: Ninety-five cases with a positive titre for the antibody were included in this study, 73 (76.8%) of them were females and 22 cases (23.2%) were males. The age of the patients ranged between 4 and 75 years with a mean age ± standard deviation of 32.3±14.7. The sensitivity was the highest in Marsh IIIC and lowest in Marsh IIIA (95% versus 68% respectively). The specificity was moderate (76%) for all subtypes of Marsh III. CONCLUSION: This study showed a positive correlation between the tissue transglutaminase titre and the degree of duodenal damage (Marsh IIIC) in patients with coeliac disease. In the presence of high tissue transglutaminase levels, duodenal biopsy might not be always necessary for diagnosis, particularly in symptomatic patients.

Medical devices; immunology and microbiology devices; classification of norovirus serological reagents. Final rule.

The Food and Drug Administration (FDA) is classifying norovirus serological reagents into class II (special controls). The special control that will apply to these devices is the guidance document entitled ``Class II Special Controls Guidance Document: Norovirus Serological Reagents.'' The Agency is classifying these devices into class II (special controls) because special controls, in addition to general controls, will provide a reasonable assurance of safety and effectiveness of these devices and there is sufficient information to establish special controls.

Immunology and microbiology devices; reclassification of the herpes simplex virus serological assay device. Final rule.

The Food and Drug Administration (FDA) is amending the special controls for the herpes simplex virus (HSV) serological assay device type, which is classified as class II (special controls). These device types are devices that consist of antigens and antisera used in various serological tests to identify antibodies to herpes simplex virus in serum, and the devices that consist of herpes simplex virus antisera conjugated with a fluorescent dye (immunofluorescent assays) used to identify herpes simplex virus directly from clinical specimens or tissue culture isolates derived from clinical specimens.

Medical devices; ovarian adnexal mass assessment score test system; labeling; black box restrictions. Final rule.

The Food and Drug Administration (FDA) is amending the regulation classifying ovarian adnexal mass assessment score test systems to restrict these devices so that a prescribed warning statement that addresses a risk identified in the special controls guidance document must be in a black box and must appear in all labeling, advertising, and promotional material. The black box warning mitigates the risk to health associated with off-label use as a screening test, stand-alone diagnostic test, or as a test to determine whether or not to proceed with surgery.

Enhanced classification of Chagas serologic results and epidemiologic characteristics of seropositive donors at three large blood centers in Brazil.

BACKGROUND: A major problem in Chagas disease donor screening is the high frequency of samples with inconclusive results. The objective of this study was to describe patterns of serologic results among donors to the three Brazilian REDS-II blood centers and correlate with epidemiologic characteristics. STUDY DESIGN AND METHODS: The centers screened donor samples with one Trypanosoma cruzi lysate enzyme immunoassay (EIA). EIA-reactive samples were tested with a second lysate EIA, a recombinant-antigen based EIA, and an immunfluorescence assay. Based on the serologic results, samples were classified as confirmed positive (CP), probable positive (PP), possible other parasitic infection (POPI), and false positive (FP). RESULTS: In 2007 to 2008, a total of 877 of 615,433 donations were discarded due to Chagas assay reactivity. The prevalences (95% confidence intervals [CIs]) among first-time donors for CP, PP, POPI, and FP patterns were 114 (99-129), 26 (19-34), 10 (5-14), and 96 (82-110) per 100,000 donations, respectively. CP and PP had similar patterns of prevalence when analyzed by age, sex, education, and location, suggesting that PP cases represent true T. cruzi infections; in contrast the demographics of donors with POPI were distinct and likely unrelated to Chagas disease. No CP cases were detected among 218,514 repeat donors followed for a total of 718,187 person-years. CONCLUSION: We have proposed a classification algorithm that may have practical importance for donor counseling and epidemiologic analyses of T. cruzi-seroreactive donors. The absence of incident T. cruzi infections is reassuring with respect to risk of window phase infections within Brazil and travel-related infections in nonendemic countries such as the United States.

Microbiology devices; reclassification of Herpes simplex virus types 1 and 2 serological assays. Direct final rule.

The Food and Drug Administration (FDA) is implementing a direct final rule correcting the regulation classifying herpes simplex virus (HSV) serological assays by removing the reference to HSV serological assays other than type 1 and type 2. When reclassifying this device, FDA mistakenly distinguished between HSV serological assays type 1 and type 2 and all other HSV serological assays. At that time, and today, the only preamendments HSV serological assays which FDA was aware of were type 1 and type 2 and, therefore, the classification of HSV assays other than type 1 and type 2 was incorrect. FDA is correcting the classification of this device to eliminate possible confusion resulting from this error. Elsewhere in this issue of the Federal Register, we are publishing a companion proposed rule under FDA's usual procedure for notice and comment to provide a procedural framework to finalize the rule in the event we receive significant adverse comment and withdraw this direct final rule.

Microbiology devices; reclassification of herpes simplex virus types 1 and 2 serological assays. Final rule.

The Food and Drug Administration (FDA) is reclassifying herpes simplex virus (HSV) types 1 and/or 2 (HSV 1 and 2) serological assays from class III (premarket approval) to class II (special controls). FDA had earlier proposed this reclassification on its own initiative based on new information. Elsewhere in this issue of the Federal Register, FDA is announcing the availability of a class II special controls guidance entitled "Class II Special Controls Guidance Document: Herpes Simplex Virus Types 1 and 2 Serological Assays."

Microbiology devices; reclassification of hepatitis A virus serological assays. Final rule.

The Food and Drug Administration (FDA) is issuing a final rule to reclassify hepatitis A virus (HAV) serological assays from class III (premarket approval) into class II (special controls). FDA is taking this action after reviewing a reclassification petition submitted by Beckman Coulter, Inc. Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the guidance document entitled "Guidance for Industry and FDA Staff: Class II Special Controls Guidance Document: Hepatitis A Virus Serological Assays" that will serve as the class II special control for these devices.

Medical devices; immunology and microbiology devices; classification of the beta-glucan serological assay. Final rule.

The Food and Drug Administration (FDA) is classifying the beta-glucan serological reagent device into class II (special controls). The special control that will apply to the device is the guidance document entitled "Class II Special Controls Guidance Document: Serological Assays for the Detection of Beta-Glucan." The agency is taking this action in response to a petition submitted under the Federal Food, Drug, and Cosmetic Act (the act) as amended by the Medical Device Amendments of 1976 (the 1976 amendments), the Safe Medical Devices Act of 1990, the Food and Drug Administration Modernization Act of 1997, and the Medical Device User Fee and Modernization Act of 2002. The agency is classifying the device into class II (special controls) in order to provide a reasonable assurance of safety and effectiveness of the device. Elsewhere in this issue of the Federal Register, FDA is publishing a notice of availability of a guidance document that is the special control for this device.

Development, implementation, and impact of acceptability criteria for serologic tests for infectious diseases.

Serologic testing is essential for the diagnosis of some infectious diseases and yet is fraught with potential pitfalls. All parts of the diagnostic process must be optimized to ensure that serologic tests perform adequately. Recognizing that a lack of clinical data and correctly timed, paired sera frequently led to uninterpretable serology results at our laboratory, we developed and implemented simple acceptability criteria for serologic tests. We assessed the impact of these criteria by comparing submissions and results for the year before and the year after implementation of the criteria. The number of serologic tests performed declined by 25% after implementation of the acceptability criteria, despite an increase in requests for serologic tests. Inappropriate testing of acute-phase sera alone fell from 49 to 0% (P < 0.001) for the tests monitored. Appropriate submission of paired sera rose from 9 to 19% (P = 0.006). The proportion of results classified as interpretable rose from 52 to 100% (P < 0.001). We recommend that acceptability criteria be developed and applied to samples submitted to clinical microbiology laboratories for serologic testing.

Current laboratory diagnosis of Q fever.

Q fever is a worldwide zoonosis caused by the strictly intracellular bacterium Coxiella burnetii. Among symptomatic patients (one-half of patients remain asymptomatic), acute Q fever most frequently manifests as a self-limited febrile illness, pneumonia, or hepatitis. Endocarditis is the predominant form of chronic Q fever. All the classical techniques of bacteriology may be used for diagnosis of C burnetii infection. Nonetheless, because of the risk of contamination, isolation must be performed in biosafety level 3 laboratories. Moreover, to date no diagnostic tests for detection by polymerase chain reaction or specific antibodies for immunochemistry are available commercially. Hence, Q fever is diagnosed in most cases by serology. The most reliable technique appears to be micro-immunofluorescence, which exhibits both good sensitivity and specificity. A wider use of this serology in cases of blood culture-negative endocarditis, atypical pneumonia, unexplained fever, and hepatitis should lead to an increase of diagnosed cases.

Comparison of electrophoretic protein profiles of campylobacter jejuni subsp. jejuni isolated from different animal species

Electrophoretic protein profiles of Campylobacter jejuni subsp. jejuni strains isolated from feces of seven animal species, including man, were compared. Fourteen strains (two from each species) plus two human strains and the reference one, were ruptured by ultrasound and their total soluble proteins were analyzed by SDS-PAGE technique in a 12(per cent) polyacrylamide gel with computerized densitometric reading by the molecular analyst software. All the strains had bands in common that correspond to 45 and 66 Kda molecular weight. The disagreement corresponded to a 97 to 200 Kda molecular weight region. From the 17 strains, 13 (76.5 per cent), were classified as biotype I, three (17.6 per cent) as biotype II and one (5.8 per cent) as biotype III. Since protein extracts were obtained from cells grown under identical conditions, and thus, able to express the same phenotype, this disagreement region could be related to different genotypes or serotypes.

Viral hepatitis? Which test should I order?

BACKGROUND: There are a multitude of viruses that may cause hepatitis. The laboratory diagnosis of viral hepatitis is important in order to plan immediate patient management, determine treatment choices and provide patient education in order to limit transmission of infections to others. OBJECTIVE: This article outlines laboratory investigations that may be routinely ordered to assist in determining the etiology of viral hepatitis and summarises some preventive and treatment strategies that may be adopted. DISCUSSION: Investigations to determine exposure to infection are routinely performed and include simple serological tests, while tests to follow the course of infection or response to treatment may involve newer molecular techniques, including polymerase chain reaction (PCR), genotyping and viral quantification.

Importancia de los marcadores serológicos en el diagnóstico de la enfermedad celíaca / Serological markers of coeliac disease

En este artículo se revisa la sensibilidad y especificidad de los diferentes marcadores serológicos de enfermedad celíaca: anticuerpos antigliadina, antiendomisio, antirreticulina y antitransglutaminasa tisular. La meta continúa siendo el desarrollo de un test que pueda reemplazar a la biopsia intestinal en el diagnóstico de la enfermedad celíaca (AU)

Valoración crítica en los tests de serodiagnóstico / Critical evaluation of serumdiagnostic tests

La calidad del diagnóstico serológico es dada por la validez y confiabilidad de su resultado. La validez de estos resultados dependen de las medidas de control empleadas antes, durante y después de cada prueba. La reelevancia del diagnóstico de la infección pre o post-transfuncional lleva implícita la necesidad de establecer programas de control de calidad que eviten las consecuencias de resultados falsos positivos o falsos negativos. Los resulatados de pruebas y ensayos son índices que nos van a permitir establecer las necesidad de cambiar el algoritmo dentro de un centro de diagnóstico. En el artículo se detallan algunos de los ejercicios de que disponemos para valorar los test diagnóstico

Valoración crítica en los tests de serodiagnóstico / Critical evaluation of serumdiagnostic tests

La calidad del diagnóstico serológico es dada por la validez y confiabilidad de su resultado. La validez de estos resultados dependen de las medidas de control empleadas antes, durante y después de cada prueba. La reelevancia del diagnóstico de la infección pre o post-transfuncional lleva implícita la necesidad de establecer programas de control de calidad que eviten las consecuencias de resultados falsos positivos o falsos negativos. Los resulatados de pruebas y ensayos son índices que nos van a permitir establecer las necesidad de cambiar el algoritmo dentro de un centro de diagnóstico. En el artículo se detallan algunos de los ejercicios de que disponemos para valorar los test diagnóstico (AU)