Diagnosis of hepatitis A and B by testing saliva

Adjustments for oral fluid quality and collection methods improve prediction of circulating tetanus antitoxin: Approaches for correcting antibody concentrations detected in a non-invasive specimen

OBJECTIVES

To examine whether anti-tetanus toxoid (anti-TT) immunoglobulin G (IgG) levels measured in oral fluid and adjusted for collection difficulties and specimen quality are associated with total IgG and anti-TTIgG in oral fluid and assess if statistical adjustment for them improves prediction of anti-TT IgG in serum.

METHODS

267 children, ages 12 to 15 months, enrolled in the M-SIMU randomized controlled trial participated in this nested cross-sectional analysis. Venous blood and oral fluid (OF) specimens were collected, and OF collection difficulties such as crying or gagging were recorded. OF volume was documented and total IgG was measured in OF specimens and anti-TT IgG was measured in OF and serum by enzyme immunoassay (EIA). Collection difficulties, volume and sociodemographic characteristics were assessed in relation to total IgG and anti-TT IgG in OF via multivariate regression. These models were extended to evaluate the association between anti-TT IgG in OF and in serum. A prediction model was developed to adjust anti-TT IgG in OF estimates as proxy for serum.

RESULTS

Blood in the specimen, sores in the mouth and crying were positively associated with total IgG concentration while high oral fluid volume and sucking on the swab were inversely associated. None were significant predictors of anti-TT IgG in OF after adjusting for total IgG (geometric mean [GM] ratio: 1.99; 95% confidence interval: 1.78-2.24) and vaccination history (GM ratio: 2.44; 95% CI: 1.98-3.01). When predicting anti-TT IgG levels in serum with OF, total IgG modified the effect of anti-TT IgG in OF.

CONCLUSIONS

Anti-TT IgG in OF is a good proxy for levels in serum, after controlling for total IgG in the specimen and other variables. Post hoc adjustments for OF volume and total IgG concentration are an important consideration when conducting serosurveys with oral fluid.

Prevention of Hepatitis A Virus Infection in the United States: Recommendations of the Advisory Committee on Immunization Practices, 2020

HEPATITIS A IS A VACCINE-PREVENTABLE, COMMUNICABLE DISEASE OF THE LIVER CAUSED BY THE HEPATITIS A VIRUS (HAV). THE INFECTION IS TRANSMITTED VIA THE FECAL-ORAL ROUTE, USUALLY FROM DIRECT PERSON-TO-PERSON CONTACT OR CONSUMPTION OF CONTAMINATED FOOD OR WATER. HEPATITIS A IS AN ACUTE, SELF-LIMITED DISEASE THAT DOES NOT RESULT IN CHRONIC INFECTION. HAV ANTIBODIES (IMMUNOGLOBULIN G [IGG] ANTI-HAV) PRODUCED IN RESPONSE TO HAV INFECTION PERSIST FOR LIFE AND PROTECT AGAINST REINFECTION; IGG ANTI-HAV PRODUCED AFTER VACCINATION CONFER LONG-TERM IMMUNITY. THIS REPORT SUPPLANTS AND SUMMARIZES PREVIOUSLY PUBLISHED RECOMMENDATIONS FROM THE ADVISORY COMMITTEE ON IMMUNIZATION PRACTICES (ACIP) REGARDING THE PREVENTION OF HAV INFECTION IN THE UNITED STATES. ACIP RECOMMENDS ROUTINE VACCINATION OF CHILDREN AGED 12-23 MONTHS AND CATCH-UP VACCINATION FOR CHILDREN AND ADOLESCENTS AGED 2-18 YEARS WHO HAVE NOT PREVIOUSLY RECEIVED HEPATITIS A (HEPA) VACCINE AT ANY AGE. ACIP RECOMMENDS HEPA VACCINATION FOR ADULTS AT RISK FOR HAV INFECTION OR SEVERE DISEASE FROM HAV INFECTION AND FOR ADULTS REQUESTING PROTECTION AGAINST HAV WITHOUT ACKNOWLEDGMENT OF A RISK FACTOR. THESE RECOMMENDATIONS ALSO PROVIDE GUIDANCE FOR VACCINATION BEFORE TRAVEL, FOR POSTEXPOSURE PROPHYLAXIS, IN SETTINGS PROVIDING SERVICES TO ADULTS, AND DURING OUTBREAKS.

Utility of oral fluid samples for hepatitis B antibody detection in real life conditions

BACKGROUND

Hepatitis B virus (HBV) testing in oral fluid samples may provide advantages in diagnosis, screening or prevalence studies, especially among individuals with venous access difficulties. This study aims to optimize one commercially available assay for detecting total anti-HBc marker in oral fluid samples and to evaluate its utility under real life conditions in different settings for the purposes of prevalence and diagnostic studies.

METHODS

Oral fluid was collected using a Salivette device and some parameters were initially evaluated: type of elution buffer and sample volume. Thereafter, the utility of oral fluid samples for detection of anti-HBc was evaluated in real life conditions in which, 1296 individuals gave serum and oral fluid samples. All serum samples were submitted to commercial EIAs to detect total anti-HBc, according to the manufacturer's instructions and oral fluid samples according to previous optimization.

RESULTS

In optimization evaluation, PBS/BSA 0.5% and 100 μL of oral fluid (volume was two-fold increased compared to serum in EIA) were chosen as transport buffer and sample volume. In the field study, anti-HBc was detected in 211 out of 1296 serum samples giving overall oral fluid sensitivity of 52.6% and specificity of 96%. Concordance was higher in ambulatory setting (67.7) compared to general population (31.8). Mean ± standard deviation values of optical density/cutoff (OD/CO) in serum samples were higher in false-negative oral fluid samples than those seen in true positive samples. Sensitivity was higher in those presenting active infection compared to anti-HBc isolate and past infection. Sensitivity also increased in the ambulatory group when HCV individuals were excluded.

CONCLUSIONS

It was possible to optimize a commercial EIA for detecting anti-HBc in oral fluid samples and where the highest concordance was found in ambulatory settings and among individuals with active infection.

Applicability of Oral Fluid and Dried Blood Spot for Hepatitis B Virus Diagnosis

Hepatitis B virus (HBV) is one of the major causes of chronic liver disease worldwide; however most of individuals are not aware about the infection. Oral fluid and dried blood spot (DBS) samples may be an alternative to serum to HBV diagnosis to increase the access to diagnosis in remote areas or high-risk groups. The main objective of this review is to give an insight about the usefulness of oral fluid and DBS for detecting HBV markers. Several groups have evaluated the detection of HBsAg, anti-HBc, and anti-HBs markers in oral fluid and DBS samples demonstrating 13 to 100% of sensitivity and specificity according different groups, sample collectors, and diagnosis assays. In the same way, HBV DNA detection using oral fluid and DBS samples demonstrate different values of sensitivity according type of collection, studied group, extraction, and detection methods. Thus, serological and molecular diagnostic tests demonstrated good performance for detecting HBV using oral fluid and DBS according some characteristics and could be useful to increase the access to the diagnosis of HBV.

Longitudinal Study of Hepatitis A Infection by Saliva Sampling: The Kinetics of HAV Markers in Saliva Revealed the Application of Saliva Tests for Hepatitis A Study

Despite the increasing numbers of studies investigating hepatitis A diagnostic through saliva, the frequency and the pattern of hepatitis A virus (HAV) markers in this fluid still remains unknown. To address this issue, we carried on a longitudinal study to examine the kinetics of HAV markers in saliva, in comparison with serum samples. The present study followed-up ten patients with acute hepatitis A infection during 180 days post diagnosis (dpd). Total anti-HAV was detected in paired serum and saliva samples until the end of the follow-up, showing a peak titer at 90th. However, total anti-HAV level was higher in serum than in saliva samples. This HAV marker showed a probability of 100% to be detected in both serum and saliva during 180 dpd. The IgM anti-HAV could be detected in saliva up to 150 dpd, showing the highest frequency at 30th, when it was detected in all individuals. During the first month of HAV infection, this acute HAV marker showed a detection probability of 100% in paired samples. The detection of IgM anti-HAV in saliva was not dependent on its level in serum, HAV-RNA detection and/or viral load, since no association was found between IgM anti-HAV positivity in saliva and any of these parameter (p>0.05). Most of the patients (80%) were found to contain HAV-RNA in saliva, mainly at early acute phase (30th day). However, it was possible to demonstrate the HAV RNA presence in paired samples for more than 90 days, even after seroconversion. No significant relationship was observed between salivary HAV-RNA positivity and serum viral load, demonstrating that serum viral load is not predictive of HAV-RNA detection in saliva. Similar viral load was seen in paired samples (on average 104 copies/mL). These data demonstrate that the best diagnostic coverage can be achieved by salivary anti-HAV antibodies and HAV-RNA tests during 30-90 dpd. The long detection and high probability of specific-HAV antibodies positivity in saliva samples make the assessment of salivary antibodies a useful tool for diagnosis and epidemiological studies. The high frequency of HAV-RNA in saliva and the probability of detection of about 50%, during the first 30 dpd, demonstrate that saliva is also useful for molecular investigation of hepatitis A cases, mainly during the early course of infection. Therefore, the collection of saliva may provide a simple, cheap and non-invasive means of diagnosis, epidemiological surveys and monitoring of hepatitis A infection purposes.

Clinical and diagnostic utility of saliva as a non-invasive diagnostic fluid: a systematic review

This systematic review presents the latest trends in salivary research and its applications in health and disease. Among the large number of analytes present in saliva, many are affected by diverse physiological and pathological conditions. Further, the non-invasive, easy and cost-effective collection methods prompt an interest in evaluating its diagnostic or prognostic utility. Accumulating data over the past two decades indicates towards the possible utility of saliva to monitor overall health, diagnose and treat various oral or systemic disorders and drug monitoring. Advances in saliva based systems biology has also contributed towards identification of several biomarkers, development of diverse salivary diagnostic kits and other sensitive analytical techniques. However, its utilization should be carefully evaluated in relation to standardization of pre-analytical and analytical variables, such as collection and storage methods, analyte circadian variation, sample recovery, prevention of sample contamination and analytical procedures. In spite of all these challenges, there is an escalating evolution of knowledge with the use of this biological matrix.

Saliva specimen sampling: a noninvasive method for diagnosis and basic investigation of viral hepatitis A, B and C

Saliva is a biological fluid that is easy to collect and manipulate. Collection of saliva samples is less expensive, noninvasive and painless compared with blood collection. Due to these advantages, saliva has been investigated as an alternative fluid to serum for diagnostic and epidemiological purposes. The aim of this article was to the review research on salivary biomarkers of viral hepatitis A, B and C, highlighting their current use, collection devices, and potential applications for diagnosis and epidemiological studies. This paper also explores recent findings of saliva as a possible source of viral hepatitis transmission.

Detecting viruses by using salivary diagnostics

BACKGROUND

Diagnostics that involve the use of oral fluids have become increasingly available commercially in recent years and are of particular interest because of their relative ease of use, low cost and noninvasive collection of oral fluid for testing.

TYPES OF STUDIES REVIEWED

The authors discuss the use of salivary diagnostics for virus detection with an emphasis on rapid detection of infection by using point-of-care devices. In particular, they review salivary diagnostics for human immunodeficiency virus, hepatitis C virus and human papillomavirus. Oral mucosal transudate contains secretory immunoglobulin (Ig) A, as well as IgM and IgG, which makes it a good source for immunodiagnostic-based devices.

CLINICAL IMPLICATIONS

Because patients often visit a dentist more regularly than they do a physician, there is increased discussion in the dental community regarding the need for practitioners to be aware of salivary diagnostics and to be willing and able to administer these tests to their patients.

Salivary biomarkers--an update

Saliva is the most easily available and accessible body fluid, which makes it one of the most sought after tools in diagnostic pathology. Markers expressed in saliva can be used for diagnosis and concurrent patient follow-up of diseases ranging from hereditary disorders to infections, as well as malignancies and also analysis of therapeutic levels of drugs. The emergence of hand-held devices has made possible the elucidation of point-of-care methods and research in the field has resulted in the assimilation of knowledge useful for clinical applications.

CLINICAL RELEVANCE

This article describes some of the latest research in saliva diagnostics and provides some information on the various hand-held devices available.

Hepatitis B virus transmission in pre-adolescent schoolchildren in four multi-ethnic areas of England

The aim of this study was to estimate the amount of childhood hepatitis B virus transmission in children born in the UK, a very low-prevalence country, that is preventable only by universal hepatitis B immunization of infants. Oral fluid specimens were collected from schoolchildren aged 7-11 years in four inner city multi-ethnic areas and tested for the presence of antibody to hepatitis B core antigen (anti-HBc). Those found positive or indeterminate were followed up with testing on serum to confirm their hepatitis B status. The overall prevalence of anti-HBc in children was low [0.26%, 95% confidence interval (CI) 0.14-0.44]. The estimated average annual incidence of hepatitis B was estimated to be 29.26/100 000 children (95% CI 16.00-49.08). The total incidence that is preventable only by a universal infant immunization programme in the UK was estimated to be between 5.00 and 12.49/100 000. The study demonstrates that the extent of horizontal childhood hepatitis B virus transmission is low in children born in the UK and suggests that schools in the UK are an uncommon setting for the transmission of the virus. Targeted hepatitis B testing and immunization of migrants from intermediate- and high-prevalence countries is likely to be a more effective measure to reduce childhood transmission than a universal infant immunization programme.

Sensitivity of oral fluids for detecting influenza A virus in populations of vaccinated and non-vaccinated pigs

Please cite this paper as: Romagosa et al. (2011) Sensitivity of oral fluids for detecting influenza A virus in populations of vaccinated and non‐vaccinated pigs. Influenza and Other Respiratory Viruses.

Background/objective  We evaluated the sensitivity of PCR on oral fluids in detecting influenza virus in vaccinated and non‐vaccinated pigs.

Methods  Three‐week‐old influenza‐free pigs were divided into three groups: (i) control, non‐vaccinated, (ii) vaccinated with a commercial, heterologous vaccine, and (iii) vaccinated with an experimental, homologous vaccine. After vaccination, an influenza‐infected pig was placed in contact with each of the groups. Individual nasal swabs and pen oral fluids were collected daily. Viral RNA was tested for the presence of influenza by RRT‐PCR and virus isolation attempted from oral fluids. A pen was considered positive if at least one nasal swab was positive.

Results  Based on nasal swab results, 43·8% of pens were detected positive but only 35% based on oral fluids. Overall sensitivity of oral fluids was 80%, and virus was isolated from 51% of RRT‐PCR‐positive oral fluids. The kappa coefficient for agreement (ĸ) between oral fluids and nasal swabs was 0·82. Among groups, ĸ was 1 (95% CI, 1–1), 0·74 (95% CI, 0·55–0·92), and 0·76 (95% CI, 0·5–1) for control, heterologous, and homologous‐vaccinated groups, respectively. There was less agreement when within pen prevalence was 10% or less. Probability of detecting influenza virus in oral fluids was 99% when within pen prevalence was higher than 18% and decreased to 69% when prevalence was 9%.

Conclusions  Results indicated that pen‐based collection of oral fluids is a sensitive method to detect influenza even when within pen prevalence is low and when pigs have been vaccinated and highlight the potential use of oral fluids for influenza surveillance.

Use of saliva for early dengue diagnosis

Background

The necessity of a venous blood collection in all dengue diagnostic assays and the high cost of tests that are available for testing during the viraemic period hinder early detection of dengue cases and thus could delay cluster management. This study reports the utility of saliva in an assay that detects dengue virus (DENV)–specific immunoglobulin A (Ig A) early in the phase of a dengue infection.

Methods and Findings

Using an antigen capture anti-DENV IgA (ACA) ELISA technique, we tested saliva samples collected from dengue-confirmed patients. The sensitivity within 3 days from fever onset was over 36% in primary dengue infections. The performance is markedly better in secondary infections, with 100% sensitivity reported in saliva samples from day 1 after fever onset. Serum and salivary IgA levels showed good correlation (Pearson's r = 0.69, p<0.001). Specificity was found to be 97%.

Conclusion

Our findings suggest that this technique would be very useful in dengue endemic regions, where the majority of dengue cases are secondary. The ACA-ELISA is easy to perform, cost effective, and especially useful in laboratories without sophisticated equipment. Our findings established the usefulness and reliability of saliva for early dengue diagnosis.

The importance of laboratory diagnosis of dengue cannot be undermined. In recent years, many dengue diagnostic tools have become available for various stages of the disease, but the one limitation is that they require blood as a specimen for testing. In many incidences, phlebotomy in needle-phobic febrile individuals, especially children, can be challenging, and the tendency to forgo a dengue blood test is high. To circumvent this, we decided to work toward a saliva-based assay (antigen-capture anti-DENV IgA ELISA, ACA-ELISA) that has the necessary sensitivity and specificity to detect dengue early. Overall sensitivity of the ACA-ELISA, when tested on saliva collected from dengue-confirmed patients (EDEN study) at three time points, was 70% in the first 3 days after fever onset and 93% between 4 to 8 days after fever onset. In patients with secondary dengue infections, salivary IgA was detected on the first day of fever onset in all the dengue confirmed patients. This demonstrates the utility of saliva in the ACA-ELISA for early dengue diagnostics. This technique is easy to perform, cost effective, and is especially useful in dengue endemic countries.

Importance of the cutoff ratio for detecting antibodies against hepatitis A virus in oral fluids by enzyme immunoassay

Multiple studies have examined the use of oral fluids in modified serum-based assays aiming to replace serum in antibody detection for hepatitis A. However, the reliable detection of HAV immunity in oral fluid requires an extremely sensitive assay; most immunoassays designed for serum antibody determination lack sufficient sensitivity for this purpose. Consequently, an "in-house" competitive enzyme immunoassay (EIA) designed specifically for use with oral samples collected using a ChemBio(®) device was developed to detect total anti-HAV antibodies (IgG and IgM). This system was compared to an in-house competitive EIA and a commercial EIA considered to be the "gold standard" using corresponding serum samples (n=225) to determine the accuracy of the assay and to evaluate the importance of the cutoff ratio for the detection of anti-HAV antibodies in oral fluids. When the median serum cutoff and the optimal oral fluid cutoff (ROC analysis) obtained from the in-house competitive EIA were compared, the oral fluid cutoff was found to be 28.8% higher than the serum cutoff. When different oral fluid cutoff values were compared, a reduction of about 17% was shown to be essential to increase test accuracy. At an oral fluid cutoff value of 0.351, sensitivity and specificity were higher, reaching 91.7% and 86.2% (p<0.001, AUROC=0.915), respectively. The convenience, accuracy and non-invasive nature of the developed method make it a useful alternative to serum-based assays for discriminating between HAV-immune and non-immune individuals.

Evaluation of saliva specimens as an alternative sampling method to detect hepatitis B surface antigen

In this study, a modified enzyme immunoassay (EIA) was evaluated for the Hepatitis B surface antigen (HBsAg) among whole saliva and oral fluid samples. Specimens were collected from 115 individuals who gave serum and oral fluid using Salivette (Sarstedt, Nümbrecht, Germany) and whole saliva. Saliva specimens were tested following a modified ELISA, and the results were compared with paired serum specimens that were tested according to the supplier's instructions. Transport buffer for the oral fluids, sample volume for assay, incubation period of sample with conjugate as well as cut-off values were evaluated to optimize the assay. The highest sensitivity and specificity were obtained by increasing the incubation of sample and conjugate to 16  hr and using the area under the receiver operating characteristic curve to calculate cut-off values. HBsAg was detected in 40 oral fluids and 44 whole saliva samples out of 47 paired positive serum specimens and not detected in 64 oral fluids and 63 whole saliva samples out of 68 matched negative sera samples by the ELISA assay. There was excellent agreement between the results for the serum and saliva specimens kappa value (κ): 0.80 for oral fluid and κ: 0.87 for whole saliva and there was excellent reproducibility. Using an optimized protocol, the sensitivities of whole saliva and oral fluid were 93.6 and 85.1%, respectively, whereas specificities of whole saliva and oral fluid were 92.6 and 94.1%, respectively. Our data showed a significant promise for the use of whole saliva and oral fluid together with the modified commercial EIA for Hepatitis B virus infection surveillance.

Oral fluid for the serological and molecular diagnosis of measles

OBJECTIVES

Since measles presents mostly in children, a non-invasive sample collection technique such as oral fluid sampling would be very useful in the early detection of measles RNA and antibodies. The aim of this study was to validate the detection of anti-measles IgM and measles virus RNA in oral fluid and to make a comparison with the gold standard methods of ELISA using serum (Enzygnost(®) anti-Measles IgM) and in-house nested reverse transcriptase polymerase chain reaction (RT-PCR) using nasopharyngeal secretions.

METHODS

Three samples each from 73 measles-positive and 44 measles-negative subjects (serum, oral fluid, and nasopharyngeal secretions) were analyzed.

RESULTS

The anti-measles IgM ELISA (MicroImmune) on oral fluid was validated against the IgM ELISA (Siemens) for serum and this resulted in a sensitivity of 92% and specificity of 100%. A molecular nested RT-PCR using oral fluid was validated against the standard assay on nasopharyngeal secretions and gave a sensitivity of 100% and specificity of 100%.

CONCLUSIONS

The results confirm that both serological and molecular oral fluid assays are suitable for routine use. The use of oral fluid samples for the detection of measles virus may encourage patients, general practitioners, and pediatricians to participate in the Belgian measles surveillance system and other epidemiological studies in the framework of the World Health Organization elimination program.

An outbreak of hepatitis A affecting a nursery school and a primary school

Between March and June 2008, 12 cases of hepatitis A were notified in Winchester. Cases were from a primary school and a nursery school with no direct linkage. Hepatitis A virus (HAV) RNA sequenced from nine cases confirmed the strain in both schools to be identical. The outbreak could have affected three other schools and a maternity unit and was controlled by immunization and screening of neonates in the maternity unit by dried blood spots. No neonates were infected and no further cases were reported until 5 months later when the index case's mother became infected with same strain of virus associated with the outbreak despite vaccination. Neither the source of the outbreak or the subsequent infection of the index case's mother was identified; however, with the timing of the cases continued transmission in the community by children with asymptomatic infection or a recurrent source cannot be ruled out.

Immunodiagnosis of dengue virus infection using saliva

Keeping in view the complications and the case fatality associated with dengue virus, several serologic tests have been developed. However, the major drawback of these serologic tests is the need for a venous blood sample obtained by invasive venipuncture. As a noninvasive alternative, saliva provides a body fluid that contains antibodies of diagnostic importance. Hence, the detection of DEN-specific IgM and IgG antibodies in serum and saliva from 80 patients was compared. Salivary IgM antibodies were detected in 100% of the serum IgM-positive samples and in 30% of the serum samples that were negative for IgM antibodies. Salivary IgG antibodies were detected in 93.3% of the serum samples that were positive for anti-dengue IgG antibodies and in none of the serum IgG-negative cases. None of the specimens from the healthy controls showed the presence of IgM or IgG antibodies. The detection of both IgG and IgM antibodies in saliva correlated well with the serum IgG and IgM detection by the ELISA test (r = 0.6322 and r = 0.4227). Detection of salivary IgM antibodies by ELISA showed 100% sensitivity, 70% specificity, 90.9% positive predictive value, and 100% negative predictive value. The detection of IgG in saliva proved to be a promising tool as the sensitivity, specificity, positive predictive value, and negative predictive value were found out to be 93.3%, 100%, 100%, and 83.3%, respectively. Thus, from this study we conclude that the detection of DEN-specific salivary IgG and IgM antibodies are useful markers for dengue infection.

Epidemiological and virological characterization of a large community-wide outbreak of hepatitis A in southern Italy

A large outbreak of hepatitis A virus (HAV) infection occurred in 2004 in Campania, a region of southern Italy, with 882 cases reported between 1 January and 1 August. The local public health authorities and the Italian National Institute of Health carried out investigations in order to characterize the agent, identify the source of infection and the route of transmission, and implement appropriate control measures. A web-based reporting system enhanced the flow of information between public health authorities, providing real-time epidemic curves and frequency distributions. The same 1B HAV genotype was found in 90% of sera from a subset of patients with acute disease, suggesting a local common source. A case-control study in the municipality with the highest attack rate showed that raw seafood consumption, in particular if illegally sold in water, was strongly associated with HAV illness. Samples of seafood systematically collected from retailers were found contaminated by HAV.

An outbreak of hepatitis A among children and adults in Denmark, August 2002 to February 2003

From August 2002 to February 2003 25 cases of hepatitis A were notified from one town in Jutland. The first cases were children of three families who returned from an endemic country. The infection spread subsequently in the local community and within households. A case-control study among household index cases showed that hepatitis A was associated with contact to a case in an after-school group (OR 29.6) and with contact to a case household member in a school class or day-care centre group (OR 9.5). From a serosurvey it was estimated that for each notified patient approximately one additional infection has occurred in the households. The infection was imported by children of immigrants, born in Denmark, returning from a visit to friends and relatives in the high-incidence country of origin of their parents and was then propagated through contact between children in after-school groups, schools and their families. Immunoprophylaxis should be given to children prior to visits to friends and relatives in endemic countries and to case contacts.

Oral fluid as a medium for the detection of hepatitis B surface antigen

Currently viral antigens and antibodies are detected by traditional serological tests. However, the introduction of oral fluid as an alternative medium would allow other alternatives. The collection of oral fluid is, in comparison with venepuncture, less invasive, less painful, less expensive (i.e., no trained personal required), and safe (prevention of needle stick injuries). Also large numbers of samples can be collected easily for epidemiological purposes. Forty-three HBsAg positive and seventy-three HBsAg negative paired serum/oral fluid samples were tested. They were collected from patients attending university hospitals. The oral fluid samples were collected using the Oracol collection device and they were subjected to an IgG quantification assay to ensure their quality and quantity. The detection of HBsAg in oral fluid was carried out using a modified ETI-MAK-4 ELISA. The validation of this oral fluid test gave a sensitivity and specificity of 90.7% and 100%, respectively. The modified ETI-MAK-4 ELISA is a suitable test for oral fluid samples collected by the Oracol collection device for epidemiological purposes.

Diagnosis of norwalk virus infection by indirect enzyme immunoassay detection of salivary antibodies to recombinant norwalk virus antigen

Simple diagnostic tests are needed for the detection of norovirus (NoV) outbreaks. Salivary antibody assays provide an attractive alternative to collecting and testing serum or stool samples. Antibodies to Norwalk virus (NV) in oral fluid samples were compared with NV antibodies in serum collected from 38 volunteers challenged with NV inoculum. Pre- and postchallenge (day 4, 8, 14, and 21) saliva and serum samples were examined by enzyme immunoassay (EIA) using recombinant NV antigen. Of 18 infected subjects (those who shed NV in stool or who demonstrated immunoglobulin G [IgG] seroconversion), 15 (83%) had > or =4-fold increases in NV-specific salivary IgA and 15 (83%) had > or =4-fold increases in NV-specific salivary IgG when prechallenge and postchallenge saliva samples were compared. When the results of the IgA and IgG assays were combined, all 18 infected subjects showed > or =4-fold increases in NV-specific salivary IgG or IgA postchallenge titers compared to their prechallenge titers. One of 19 uninfected subjects had a > or =4-fold increase in NV-specific salivary IgG. The sensitivity of the combined assay results was 100%, and the specificity was 95%. NV-specific salivary IgA titers peaked around 14 days postchallenge. NV-specific salivary IgG and serum IgG titers continued to rise through 21 days postchallenge. The application of this EIA to an elementary school outbreak indicated that 67% of the subjects with confirmed infections had >4-fold rises in anti-NoV IgA when an antigen in the same genetic cluster as the outbreak virus was used. This is the first documented mucosal antibody response to NoV in children. This EIA provides a useful approach for diagnosing NoV outbreaks.

Detection of antibody to HIV in saliva: a brief review

BACKGROUND

The possibility that saliva could be used for HIV screening and diagnosis has been known since 1986. Despite the obvious advantages over venepuncture of ease of collection, safety, compliance and cost, interest in salivary testing has grown relatively slowly. Several studies have demonstrated that salivary anti-HIV testing can be highly accurate, particularly if specimen collection procedure are optimal.

OBJECTIVE

To review current knowledge about the detection of anti-HIV in oral fluids, with an emphasis on the identification of optimal procedures.

STUDY DESIGN

In the light of existing published data, the factors leading to accurate salivary diagnosis of HIV infection were identified and reviewed.

RESULTS

To achieve the best results it is essential to collect oral fluid specimens that are rich in IgG. Most IgG in the oral cavity derives from the crevicular space between the gums and the teeth, and not from salivary glands. Available methods for collecting salivary specimens are discussed. Until these collection methods are fully validated, individual specimens or at least clinical ones found anti-HIV negative should be tested for total IgG before being reported on. There is a lack of proven confirmatory methods for salivary anti-HIV and this problem is reviewed. Salivary anti-HIV testing has been employed mostly for surveillance, but life insurance applicants are increasingly screened in this way and clinical applications are under active consideration. With appropriate safeguards, diagnostic and pre-blood donation salivary testing could be introduced shortly. The necessary technology is also available to develop rapid single-use salivary tests. This would bring anti-HIV testing closer to the patient.

CONCLUSIONS

Salivary tests for anti-HIV offer advantages of convenience, economy and safety, and are more acceptable to subjects than blood tests. Further evaluation of the collection devices and assays, the introduction of safeguards against inadequate sampling and the development of suitable confirmatory assays are required. When these deficiencies have been met, salivary tests may supersede tests on serum for HIV and also other infections.

Investigation of a hepatitis A outbreak in a primary school by sequential saliva sampling

BACKGROUND

An outbreak of hepatitis A occurred in a primary school (children aged 4-11 years), starting in the Autumn of 1990 and terminating some 5 months later after some spread into the local community.

OBJECTIVES

The objectives were to monitor the spread of the virus within the primary school over time, to document infection in asymptomatic individuals and the efficacy of using saliva for HAV antibody detection in young children as an acceptable screening method by using the Salivette method and ordinary cotton tipped swabs.

STUDY DESIGN

Serial saliva samples were taken over a period of months and anti-HAV IgM and IgG antibodies measured by radioimmunoassay.

RESULTS

Twenty-seven children in the school and nine individuals from the surrounding community acquired hepatitis A. Twenty-one (78%) of the 27 children were symptomatic, as were all the affected adults. The cotton-tipped swabs were found to be as effective a method as Salivette at diagnosing infection in those in whom the methods were compared.

CONCLUSIONS

Despite many reports stating that children are more likely to be asymptomatic with HAV infection we found the majority to report significant symptoms. Young children do not easily accept serum sampling as a method for diagnosis or epidemiological studies, and we show that saliva sampling is an effective and acceptable diagnostic method.

Hepatitis A in Hispanic children who live along the United States-Mexico border: the role of international travel and food-borne exposures

OBJECTIVES

Hispanic children who live along the United States-Mexico border historically have had among the highest hepatitis A rates in the United States, but risk factors have not been well characterized. The objective of this study was to examine risk factors associated with acute hepatitis A virus (HAV) infection in Hispanic children who live along the United States-Mexico border in San Diego County, California.

METHODS

In this case-control study, hepatitis A cases among Hispanic children who were younger than 18 years reported from June 1998 through August 2000 were matched by age group and exposure period to Hispanic children who were susceptible to HAV infection. Participants and their families were interviewed about demographic information and potential sources of HAV infection, including attending child care, food and waterborne exposures, cross-border and other international travel, and travel-related activities.

RESULTS

Participants included 132 children with hepatitis A and 354 control subjects. The median age of study participants was 7 years (range: 1-17). Sixty-seven percent of case-patients traveled outside the United States during the incubation period, compared with 25% of the children without hepatitis A (odds ratio [OR]: 6.3; 95% confidence interval [CI]: 4.0-9.7); all children, except 1, had traveled to Mexico. In multivariate analysis, hepatitis A was associated with having eaten food from a taco stand or street food vendor (adjusted OR: 17.0; 95% CI: 4.1-71.1) and having eaten salad/lettuce (adjusted OR: 5.2; 95% CI: 1.3-20.1) during travel.

CONCLUSIONS

Hepatitis A among Hispanic children who live in an urban area of the United States-Mexico border is associated with cross-border travel to Mexico and food-borne exposures during travel. Travelers to areas where hepatitis A is endemic should receive hepatitis A vaccine before travel.

Hepatitis A virus and injecting drug misuse in Aberdeen, Scotland: a case-control study

To describe an epidemiological investigation of an outbreak of hepatitis A virus (HAV) infection among injecting drug users in Aberdeen, Scotland. A case-control study to determine whether transmission was facilitated by poor personal hygiene or through sharing injecting equipment. Cases were more likely to report not washing their hands after using the toilet [odds ratio (OR) = 12.9, 95% confidence interval (CI) = 1.58-105.89] or before preparing food (OR = 4.0, 95% CI = 1.01-15.8), and less likely to have washed their hands prior to preparing drugs (OR = 10.67, 95% CI = 2.14-53.07). Cases were also more likely to report recipient sharing of needles/syringes (OR = 8.27, 95% CI = 1.68-40.57), and to have had injecting contact with someone who was jaundiced (OR = 29.4, 95% CI = 3.18-271.44). The results indicate that the lack of hygiene within the context of individuals gathering to prepare and inject drugs provides ample opportunity for the transmission of HAV. Although the promotion of good hygiene and the avoidance of sharing injecting equipment are important measures in preventing HAV transmission, they are unlikely to effect major behavioural change. Such measures should, therefore, be reinforced by routinely offering HAV vaccine to injectors.

Outbreak of hepatitis A in the injecting drug user and homeless populations in Bristol: control by a targeted vaccination programme and possible parenteral transmission

OBJECTIVE

To study the use of hepatitis A virus (HAV) vaccination in controlling an outbreak of HAV in inner-city Bristol among injecting drug users (IDUs). To study whether hepatitis C virus (HCV) and hepatitis B virus (HBV) co-infection increases morbidity.

DESIGN

Community-based cohort study.

SETTING

Avon Health Authority area, UK.

PARTICIPANTS

All laboratory-confirmed cases of HAV infection notified in 2000.

INTERVENTION

Administration of a targeted vaccination, education and liaison programme.

MAIN OUTCOME MEASURES

Number of cases of HAV before and after introduction of HAV vaccination programme. Mortality and number of patients requiring hospital admission. Association of HCV and HBV co-infection with hospital admission.

RESULTS

Ninety cases of HAV were reported in the first 6 months of 2000, of whom a substantial number were IDUs and/or inner-city hostel residents. In the second 6 months of 2000, following the introduction of a vaccination programme among homeless people, hostel residents, and IDUs, the number of HAV cases fell to 33. Sixteen patients had evidence of HCV co-infection. No patient had chronic HBV infection. Two patients died as a result of HAV, and two subsequently died from drug misuse. Fifty-six per cent of HCV-co-infected patients required admission to hospital compared with 28% non-HCV-co-infected patients.

CONCLUSIONS

This is the first reported successful use of vaccination to control an outbreak of HAV in a population of IDUs and to prevent transmission to the wider population. HCV co-infection appears to increase the severity of HAV illness, as demonstrated by increased incidence of hospital admission.

The diagnostic applications of saliva--a review

This review examines the diagnostic application of saliva for systemic diseases. As a diagnostic fluid, saliva offers distinctive advantages over serum because it can be collected non-invasively by individuals with modest training. Furthermore, saliva may provide a cost-effective approach for the screening of large populations. Gland-specific saliva can be used for diagnosis of pathology specific to one of the major salivary glands. Whole saliva, however, is most frequently used for diagnosis of systemic diseases, since it is readily collected and contains serum constituents. These constituents are derived from the local vasculature of the salivary glands and also reach the oral cavity via the flow of gingival fluid. Analysis of saliva may be useful for the diagnosis of hereditary disorders, autoimmune diseases, malignant and infectious diseases, and endocrine disorders, as well as in the assessment of therapeutic levels of drugs and the monitoring of illicit drug use.

Diagnosis of dengue virus infection by detection of specific immunoglobulin M (IgM) and IgA antibodies in serum and saliva

To evaluate alternative approaches to the serological diagnosis of dengue virus (DEN) infection, the detection of DEN-specific immunoglobulin M (IgM) and IgA antibodies in serum and saliva specimens was assessed in 147 patients with symptoms of DEN infection seen at the Ministry of Health in Nicaragua. Seventy-two serum samples were determined to be positive for anti-DEN antibodies by IgM capture enzyme-linked immunosorbent assay, the routine diagnostic procedure. Serum and saliva specimens were obtained from 50 healthy adults as additional controls. IgM was detected in the saliva of 65 of the 72 serum IgM-positive cases, 6 of the 75 serum IgM-negative cases, and none of the control group, resulting in a sensitivity of 90.3% and a specificity of 92.0% and demonstrating that salivary IgM is a useful diagnostic marker for DEN infection. Detection of IgA in serum may be another feasible alternative for the diagnosis of DEN infection, with serum IgA found in 68 (94.4%) of the IgM-positive cases. In contrast, detection of IgA in saliva was not found to be a useful tool for DEN diagnosis in the present study. Further studies of the kinetics of antibody detection in another set of 151 paired acute- and convalescent-phase serum samples showed that DEN-specific IgA antibodies were detected in more acute-phase samples than were IgM antibodies. Thus, we conclude that DEN-specific IgA in serum is a potential diagnostic target. Furthermore, given that saliva is a readily obtainable, noninvasive specimen, detection of DEN-specific salivary IgM should be considered a useful, cheaper diagnostic modality with similar sensitivity and specificity to IgM detection in serum.

The use of an oral fluid immunoglobulin G ELISA for the detection of Helicobacter pylori infection in children

BACKGROUND

Enzyme linked immunosorbent assay (ELISA) evaluation of oral fluid immunoglobulin G (IgG) antibodies to Helicobacter pylori is a unique approach for both epidemiological studies and the diagnosis of infection, especially in children. The use of oral fluid sampling to evaluate specific H. pylori IgG antibodies has advantages over serum, including reduced biohazard risk and noninvasive collection. Oral fluid sampling is fast and involves minimal patient discomfort. Since children facilitate transmission of H. pylori infection, a simple, accurate, noninvasive diagnostic test is necessary for large epidemiologic studies. The aim of our study was to evaluate a new oral fluid ELISA for detection of IgG antibodies to H. pylori in children.

MATERIALS AND METHODS

We compared this new oral fluid ELISA with the HM-CAPTM serum ELISA and gastric biopsy histology using 779 oral fluid samples from children collected at 11 clinical sites across the United States. This cohort included 315 children symptomatic for abdominal pain and 464 asymptomatic. All samples were evaluated in a double blind manner. The oral fluid ELISA demonstrated a sensitivity of 76.2% and a specificity of 94.0% in children 2 months old to 201/2 years, as compared with the HM-CAPTM serologic assay. The assay's sensitivity improved to 81.3% in children aged 5 or greater and the specificity remained at 94.0%. When compared with gastric biopsy histology in the same age group, the oral fluid ELISA demonstrated a sensitivity of 71.7% and a specificity of 90.4%.

RESULTS

This new oral fluid ELISA is moderately sensitive and offers a very specific method for detecting H. pylori infection in older children, but it is of little value in children under the age of 5 years.

CONCLUSIONS

Overall, we conclude that this oral fluid ELISA does not appear to be a helpful clinical tool for the diagnosis of H. pylori infection in children.

Novel methods for the detection of microbial antibodies in oral fluid

Compared with blood, oral fluid has several advantages as a sample for antibody detection. It is simple, safe, painless, and cheap to collect. The only drawback is that while the antibody profiles indicate those in blood, they are at lower concentrations. Antibody capture assays are the method of choice for the detection of microbial antibodies in oral fluid, but their relative lack of sensitivity when based on conventional immunoassay techniques has mostly limited their use to epidemiological applications. Immuno-PCR and time-resolved fluorescence offer more sensitive detection systems that could be applied to oral fluid specimens. We review antibody detection in oral fluid and discuss immuno-PCR and time-resolved fluorescence as candidate systems. Both have the potential to broaden the applications of oral fluid testing to clinical diagnostics.

Evaluation of hepatitis C antibody testing in saliva specimens collected by two different systems in comparison with HCV antibody and HCV RNA in serum

Two different ELISA assays, the Ortho HCV 3.0 ELISA (Ortho Diagnostics Systems) and the Mono-Lisa anti-HCV Plus (Sanofi Diagnostics Pasteur) were evaluated for the detection of hepatitis C virus (HCV) antibody in saliva samples. Specimens were collected from 152 individuals who participated in a longitudinal cohort study on HIV infection, and who used illicit drugs. Saliva specimens were collected using two different systems: Salivette (Sarstedt) and Omni-Sal (Saliva Diagnostic Systems). Saliva specimens were tested following modified protocols by both ELISAs, and the results were compared with serum specimens that were tested according to the instructions of the manufacturer. Serum samples of 102 (67%) participants were positive by both assays, and 50 persons were negative for HCV antibody. A total of 99 of the 102 serum specimens were confirmed as positive using Ortho Riba HCV 3.0 (Ortho Diagnostics System) and Deciscan HCV (Sanofi Diagnostics Pasteur), and 3 yielded discrepant results. As no cut-off level is known for testing saliva samples by ELISA, 3 different levels were chosen: mean (M) + 1 standard deviation (SD), M + 2 SD, and M + 3 SD of the optical densities of saliva tests of the 50 HCV serum antibody negative persons. At a level of M + 1 SD and M + 2 SD the Salivette/Mono-Lisa combination gave the greatest proportion of HCV antibody positive saliva specimens obtained from the 102 HCV serum antibody positive participants, 88% and 79%, respectively. Differences between the various collection systems and assay combinations were not significant statistically. In 76 of the 102 persons with HCV antibodies in serum, HCV RNA was detected in serum. Salivary presence of HCV RNA, however, could not be demonstrated. The results show that the assays compared are unsuitable for diagnostic use, but the sensitivities of the assays are acceptable for use in epidemiological studies.

Dynamic study of HBsAg and HBeAg in saliva samples from patients with hepatitis B infection: diagnostic and epidemiological significance

Analysis of 505 cases history of patients among men with viral hepatitis demonstrates that HBV infected patients represent 68.9% of the total and that a non-parenteral rate of transmission is the most likely means of hepatitis B infection. Saliva and serum testing for the presence of specific HBV markers (HBsAg, HBeAg and HBV DNA) at different phases of the infection process were carried out to review the diagnostic and epidemiological value of saliva samples from patients with acute viral hepatitis B. The frequency of HBsAg detection by Enzyme Immune Assay (EIA) in saliva of patients in acute period was found to correlate with the frequency of its detection in serum. In early convalescence the frequency of detection of that antigen in serum (59.5% of patients) was significantly higher than in saliva (23.8%) (P < 0.001). The frequencies of HBeAg detection by EIA in saliva samples was significantly higher than that in serum samples in both acute phase (84.3% and 28.1% of patients, respectively) and in early convalescence (56.2% and 3.1% of patients, respectively). The study of frequencies of detection of these antigens in the dynamics of the disease up to the total recovery of patients (observations were carried out for the period of 60 days and longer) showed that in most patients there was a faster disappearance HBsAg from saliva than from serum. By the end of second month this antigen was detected in saliva of only 8.3% of patients whereas in serum in the same period HBsAg was detected in 33.3% of patients. HBeAg became undetectable in blood whereas HBs-antigenemia was still pronounced, and a month after the beginning of the disease it was not found in serum specimens. In saliva, HBeAg was detected in 95.8% of patients observed directly after admission. A month after the beginning of the disease it was detected in saliva of 66.7% of patients and, by the end of observation period, in 12.5% of patients recovered from viral hepatitis. HBV DNA revealed by PCR in saliva and serum of HBV-infected patients was detected in acute period not only in serum (84.6% of cases) but also in saliva (46.2% of cases). The data illustrate the diagnostic value of saliva and point to the possible role of saliva as a source of HBV infection.

Detection of hepatitis A antibodies by ELISA using saliva as clinical samples

The possibility of detecting acute infection and immunity using body fluids that are easier to collect than blood, mainly in children, would facilitate the investigation and follow-up of outbreaks of hepatitis A (HAV). Our study was carried out to evaluate the detection of anti-HAV IgM, IgA and total antibodies in saliva using serum samples as reference. Forty three paired serum and saliva samples were analyzed. From this total, 24 samples were obtained from children and 1 from one adult during the course of acute hepatitis A; an additional 18 samples were obtained from health professionals from Adolfo Lutz Institute. The sensitivity to detect anti-HAV IgM was 100% (95%CI: 79.1 to 100.0%), employing saliva as clinical samples. In detecting anti-HAV IgA, the sensitivity was 80. 8% (95%CI: 60.0 to 92.7%) and for the total antibodies was 82.1% (95%CI: 62.4 to 93.2%). The specificity was 100% for each. The rate of agreement was high comparing the results of serum and saliva samples for detecting HAV antibodies. We conclude that saliva is an acceptable alternative specimen for diagnosing acute hepatitis A infection, and for screening individuals to receive hepatitis A vaccine or immunoglobulin.

Diagnosis of rubella infection by detecting specific immunoglobulin M antibodies in saliva samples: a clinic-based study in Niterói, RJ, Brazil

This study was designed to investigate whether saliva could be a feasible alternative to serum for the diagnosis of recent rubella infection in a clinic setting. Forty-five paired blood and saliva samples collected 1 to 29 days after onset of illness were tested for specific immunoglobulin (Ig) M by antibody-capture radioimmunoassay (MACRIA). Rubella IgM was detected in all serum samples and in 38 (84.4%) saliva specimens. Forty-six serum and saliva samples from other patients with rash diseases were tested by MACRIA for control purposes and two saliva specimens were reactive. The saliva test had specificity of 96%. These results indicate that salivary IgM detection may be a convenient non-invasive alternative to serum for investigation of recent rubella cases, especially for disease surveillance and control programmes.

Oral fluids for the immunodiagnosis of Schistosoma mansoni infection

Saliva and oral transudate were evaluated for their potential as human specimens in the detection of IgG antibodies against soluble Schistosoma mansoni egg antigen (SEA). Preliminary laboratory testing of 49 subjects, 37 with parasitological proven infection and 12 negative controls, displayed 100% sensitivity in ELISA using serum and oral transudate and 94.6% using saliva. The specificity of the ELISA with serum was 100% versus 91.7% with both oral fluids. Significant Spearman rank correlations of anti-SEA IgG levels with egg counts were observed for serum, oral transudate and saliva (P < 0.05). The sensitivity of dot-ELISA was 100% for serum, 89% for transudate and 81% for saliva, and specificity was 100% for all 3 samples. The immunodiagnostic value of ELISA for the detection of anti-SEA IgG antibodies in oral transudate was further evaluated in 197 individuals from an endemic area of Brazil. The ELISA using serum and oral transudate showed sensitivities of 98.8% and 100% respectively and specificities of 67.8% and 64.3% respectively. Use of oral fluids for the diagnosis of S. mansoni infection was equivalent to sera with respect to test efficacy, offering an alternative to blood collection.

Detection of measles specific IgG in oral fluid using an FITC/anti-FITC IgG capture enzyme linked immunosorbent assay (GACELISA)

An IgG antibody capture enzyme linked immunosorbent assay (GACELISA) for the detection of measles specific IgG in oral fluid was developed using an FITC/anti-FITC amplification system. The GACELISA was evaluated by testing paired oral fluid and serum samples from 787 subjects in an epidemiological study of measles in rural Ethiopia. Oral fluids were tested by GACELISA and corresponding serum samples by a sensitive indirect ELISA for measles IgG (Behring Enzygnost). By comparison with the serum measles IgG assay, the oral fluid GACELISA had a sensitivity of 97.4% (95% confidence intervals: 95.9, 98.2) and a specificity of 90.0% (81.9, 94.3), with no significant differences observed by age group. Total IgG concentrations were measured on a subset of 160 oral fluids by an in-house ELISA. This showed that false negative GACELISA results tended to occur in samples with low concentrations of total IgG, although the trend was not statistically significant. It is concluded that the overall performance of the GACELISA was satisfactory, showing close agreement to the serum ELISA, and has potential to serve as an easily transferable tool for large scale epidemiological studies as required for the World Health Organisation's programme for the global control of measles.

Human immunodeficiency virus antibody testing by enzyme-linked fluorescent and western blot assays using serum, gingival-crevicular transudate, and urine samples

The aim of the present study was to evaluate the possible utilization of saliva and urine as alternative samples to serum for the diagnosis of human immunodeficiency virus (HIV) infection. A total of 302 individuals participated in the study: 187 HIV-infected individuals (106 had Centers for Disease Control and Prevention [CDC] stage II infection, 19 had CDC stage III infection, and 62 had CDC stage IV infection) and 115 noninfected persons (46 of the noninfected persons were blood donors and 69 belonged to a group at high risk of HIV infection). Paired saliva and urine samples were taken from each of the participants in the study. The presence of HIV-specific antibodies was detected by an enzyme-linked fluorescent assay (ELFA), and the result was confirmed by Western blot analysis (WB). The ELFA with saliva gave maximum sensitivity and specificity values, while ELFA had lower sensitivity (95.2%) and specificity (97. 4%) values for detection of HIV antibody in urine samples. WB with all saliva samples fulfilled the World Health Organization criterion for positivity, while only 96.8% of the urine samples were confirmed to be positive by WB. Among the four reactivity patterns found by WB of these alternative samples, the most frequent included bands against three groups of HIV structural proteins (was ENV, POL, and GAG). The reactivity bands most frequently observed were those for the proteins gp160 and gp120. The least common reactivity band was the band for protein p17. The detection of HIV antibodies in saliva samples by means of ELFA with the possibility of later confirmation by WB makes saliva an alternative to serum for possible use in the diagnosis of infection. In contrast, HIV antibody detection in urine samples by the same methodology (ELFA) could be taken into consideration for use in epidemiological studies.

Diagnosis of dengue infection by detecting specific immunoglobulin M antibodies in saliva samples

To investigate whether saliva could be used for diagnosis of recent dengue, serum and saliva samples were collected simultaneously from patients with suspected dengue infection. Sera (1:10 dilution) and saliva (undiluted) were tested by using an IgM capture enzyme linked immunosorbent assay (MAC-ELISA) with minor modifications (serum and saliva absorption for 3 h at 37 degrees C). The quality of saliva was evaluated by determining the IgG total concentration (enzyme immunoassay) which ranged from 2.7 to > 50 mg/l. Recent dengue infection was confirmed in 38 cases. Forty-six serum and saliva specimens were collected from these patients 1-30 days after the onset of symptoms. IgM was detected in 65.8% saliva samples. High rate of positivity ( > 80%) was observed for the saliva samples collected > or = 5 days after the onset of the disease. Fifty serum and saliva samples from other 32 patients with rash diseases were also tested and all the specimens were unreactive by MAC-ELISA. These results indicate that saliva may be a convenient non-invasive alternative to serum for diagnosis of recent dengue fever infection, especially for epidemiological studies during outbreaks of the disease.

Detection of specific antibodies in saliva during dengue infection

Saliva was collected prospectively from patients presenting with suspected dengue infection 4 to 8 days after the onset of symptoms and assayed by a commercial dengue immunoglobulin M (IgM) and IgG capture enzyme-linked immunosorbent assay (ELISA) (PanBio Dengue Duo ELISA). Laboratory diagnosis was based on virus isolation and on hemagglutination inhibition (HAI) assay and an in-house IgM and IgG capture ELISA. With a positive result defined as either salivary IgM or IgG levels above the cutoff value, an overall sensitivity of 92% was obtained for both primary- and secondary-dengue patients (22 of 24), while no patients with non-flavivirus infections (n = 11) and no healthy laboratory donors (n = 17) showed elevation of salivary antidengue antibody (100% specificity). Salivary IgG levels correlated well with serum HAI titer (r = 0.78), and salivary IgG levels could be used to distinguish between primary- and secondary-dengue virus infections.

Salivary diagnosis of measles for surveillance: a clinic-based study in Niterói, state of Rio de Janeiro, Brazil

This study was designed to investigate whether saliva could be a feasible alternative to serum for the diagnosis of recent measles infection in a clinic setting. Forty-two paired blood and saliva samples collected 1 to 16 days after onset of illness from 29 patients with clinical measles were tested for specific immunoglobulin (Ig) M by antibody-capture radioimmunoassay. Measles IgM was detected in all serum samples and in 39 (92.9%) saliva specimens. Between 1 and 3 weeks after illness onset, virus-specific IgM was detected in 100% of saliva samples. Measles IgM was also detected in 17 saliva specimens, not paired with blood samples, collected from study patients 5 days to 3 weeks after onset. Our results indicate that salivary IgM detection is a suitable non-invasive method for investigation of notified cases under conditions of routine clinic use.

New, ultrasensitive enzyme immunoassay for detecting vaccine- and disease-induced hepatitis A virus-specific immunoglobulin G in saliva

Although detection of disease-induced hepatitis A virus (HAV)-specific antibodies in saliva has been successfully utilized in a few epidemiological studies, available assays fail to detect lower salivary anti-HAV levels associated with vaccine-induced immunity. We present a new capture enzyme immunoassay which employs a three-layer antibody recognition system. Evaluation of paired saliva-serum specimens from 1,025 international travellers, 134 other volunteers, and 91 hepatitis A vaccine recipients demonstrated 99.6% (95% confidence interval, 98.4 to 99.9) specificity and 98.7% (95% confidence interval, 97.7 to 99.4) sensitivity of this salivary assay in differentiating between immune and susceptible individuals, compared with serum-based methods. We conclude that this assay is sufficiently sensitive for reliable detection of both vaccine- and infection-induced HAV-specific immunoglobulin G in saliva, even when corresponding anti-HAV levels in serum are very low (< 1 IU/ml).

Prevalence of markers for hepatitis B virus and HIV-1 among drug injectors in London: injecting careers, positivity and risk behaviour

Concerns about the risks of HIV infection among drug injectors have eclipsed concerns about the prevalence and transmission of hepatitis, and in particular hepatitis B virus infection. Findings are reported from surveys undertaken with two separate community-recruited samples of drug injectors in London collected in 1992 (n = 505) and in 1993 (n = 507). Anonymized confirmed testing of saliva shows 51.5% of drug injectors in 1992 and 47.9% in 1993 to be antibody positive to the core antigen of hepatitis B virus (anti-HBc). Approximately half of the drug injectors confirmed as anti-HBc positive were unaware that they had been infected with hepatitis. Anti-HIV-1 prevalence was considerably lower at 7.0% in 1992 and 6.9% in 1993. Multivariate analyses showed anti-HBc positivity to be most likely among older injectors with longer injecting careers who had a history of having shared used needles and syringes. HIV-1 positivity was also associated with a history of having shared injecting equipment as well as with recent sharing (i.e. in the last 6 months). Unlike anti-HBc positivity, there were no associations between HIV-1 positivity and age or length of injecting career. Younger injectors with shorter injecting careers were more likely to report recent sharing of used injecting equipment than older injectors with longer injecting careers. We note the potential for continued transmission of HBV and HIV-1, particularly among younger injectors. We recommend an integrated strategy to maximize the health of drug injectors, of which HIV and HBV prevention is a part. There is a need to widen the availability of HBV vaccinations for HBV negative drug injectors and their sexual partners and for clear guidelines to drug injectors about the relative efficacy of bleach to disinfect injecting equipment of HBV and HIV.

Potential for diagnosis of intestinal nematode infections through antibody detection in saliva

The present study was the first to investigate the potential of saliva in community diagnosis of the major human intestinal nematode infections, Trichuris trichiura, Ascaris lumbricoides, and the hookworms. Immunoglobulin G (IgG) antibodies specific to parasite antigens were quantified in saliva samples of 187 individuals (all ages) from a St Lucian community, and 120 school-aged children from Tanga region, Tanzania, and relationships with current infection status (determined by numbers of parasite eggs in stool) were examined. For T. trichiura infection, the age relationships of parasite-specific salivary IgG antibodies mirrored those of infection intensity at the community level. Within both areas, children with current T. trichiura infection exhibited significantly higher anti-T. trichiura salivary IgG responses than uninfected children. Similar trends were apparent for A. lumbricoides and hookworm infections, though not to a level of statistical significance. Comparison of mean T. trichiura infection levels and antibody responses in age-matched children from St Lucia and Tanzania suggested that measurement of parasite-specific salivary IgG may have potential as a marker of transmission intensity at the community level.

A school outbreak of parvovirus B19 infection investigated using salivary antibody assays

An outbreak of parvovirus B19 infection at a primary school was investigated using saliva samples. Antibody capture immunoassays for salivary B19 IgG and IgM were developed using a recombinant B19 antigen and monoclonal antibody to B19 virus. Evaluation of the salivary IgG assay using paired serum and saliva samples from 43 staff at St Thomas' Hospital showed that it had a sensitivity of 100% and a specificity of 95%. Evaluation of the salivary B19 IgM assay using 87 paired blood and saliva samples from a study of general practitioner rubella notifications showed it had a sensitivity of 60% and a specificity of 98%. Using the salivary assay the level of B19 IgG within 2 weeks of the start of the outbreak ranged from 5-33% in children and 29% in staff. By detecting salivary B19 IgM and/or B19 IgG seroconversions, attack rates of 8-50% in children in different classes and 47% in staff were observed. Household transmission was also studied and an attack rate of 45% was recorded in 11 susceptibles. After the outbreak, the level of B19 IgG in children with the highest attack rates was 60-70%, similar to that seen in adults in the UK. This study highlights the risk of B19 infection in an institutional setting and shows that saliva samples are a useful alternative to blood.