Oral fluid collection by post for viral antibody testing

Rapid Salivary IgG Antibody Screening for Hepatitis A

Hepatitis A virus (HAV) is a common infection that is transmitted through the fecal-oral route, shed in the stool of infected individuals, and spread either by direct contact or by ingesting contaminated food or water. Each year, approximately 1.4 million acute cases are reported globally with a major risk factor for exposure being low household socioeconomic status. Recent trends show a decrease in anti-HAV antibodies in the general population, with concomitant increases in the numbers of HAV outbreaks. In line with a recreational water study, this effort aims to assess the prevalence of salivary IgG antibodies against HAV and subsequent incident infections (or immunoconversions) in visitors to a tropical beach impacted by a publicly owned treatment works (POTW). We applied a multiplex immunoassay to serially collected saliva samples gathered from study participants who recreated at Boquerón Beach, Puerto Rico. Analysis of assay results revealed an immunoprevalence rate of 16.17% for HAV with 1.43% of the cohort immunoconverting to HAV. Among those who immunoconverted, 10% reported chronic gastrointestinal symptoms and none experienced diarrhea. Tests on water samples indicated good water quality with low levels of fecal indicator bacteria; however, the collection and analysis of saliva samples afforded the ability to detect HAV infections in beachgoers. This rapid assay serves as a cost-effective tool for examining exposure to environmental pathogens and can provide critical information to policy makers, water quality experts, and risk assessment professionals seeking to improve and protect recreational water and public health.

Point of care and oral fluid hepatitis B testing in remote Indigenous communities of northern Australia

Many Indigenous Australians in northern Australia living with chronic hepatitis B are unaware of their diagnosis due to low screening rates. A venous blood point of care test (POCT) or oral fluid laboratory test could improve testing uptake in this region. The purpose of this study was to assess the field performance of venous blood POCT and laboratory performance of an oral fluid hepatitis B surface antigen (HBsAg) test in Indigenous individuals living in remote northern Australian communities. The study was conducted with four very remote communities in the tropical north of Australia's Northern Territory. Community research workers collected venous blood and oral fluid samples. We performed the venous blood POCT for HBsAg in the field. We assessed the venous blood and oral fluid specimens for the presence of HBsAg using standard laboratory assays. We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the POCT and oral fluid test, using serum laboratory detection of HBsAg as the gold standard. From 215 enrolled participants, 155 POCT and 197 oral fluid tests had corresponding serum HBsAg results. The POCT had a sensitivity of 91.7% and specificity of 100%. Based on a population prevalence of 6%, the PPV was 100% and NPV was 99.5%. The oral fluid test had a sensitivity of 56.8%, specificity of 98.1%, PPV of 97.3% and NPV of 65.9%. The venous blood POCT has excellent test characteristics and could be used to identify individuals with chronic HBV infection in high prevalence communities with limited access to health care. Oral fluid performance was suboptimal.

Nursing Staff Knowledge of the Hepatitis B Virus Including Attitudes and Acceptance of Hepatitis B Vaccination: Development of an Effective Program

Data for this study in a large tertiary referral teaching hospital in Dublin, Ireland were collected by anonymous self administered questionnaires. A total of 137 questionnaires were distributed to nurses working in five wards with a response rate of 88% (120). Objectives included identifying levels of awareness of the infectivity of the hepatitis B virus, ascertaining levels of knowledge of hepatitis B vaccination, and identifying attitudes resulting in acceptance of hepatitis B vaccine. Ninety seven respondents (82%) knew hepatitis B was 100 times more infective than HIV. Ninety eight respondents (83%) had completed a full course of hepatitis B immunizations. Ninety six respondents (93%) reported a hepatitis B antibody level on completion of the immunizations, 13 (14%) knew their actual titer, and 49 of 63 respondents (78%) reported immunity. Factors influencing decisions to accept vaccination included information related to the benefits of the vaccine from an occupational health physician or nurse and the vaccine being provided free of charge. Nurses in this study had an understanding of the hepatitis B infection. The number of nurses choosing to be vaccinated and having an antibody level test performed post-vaccination was high in this group. Most nurses in this study believed they were immune to hepatitis B even though a significant number did not know their hepatitis B antibody level.

Saliva and viral infections

Over the last 10 years there have been only a handful of publications dealing with the oral virome, which is in contrast to the oral microbiome, an area that has seen considerable interest. Here, we survey viral infections in general and then focus on those viruses that are found in and/or are transmitted via the oral cavity; norovirus, rabies, human papillomavirus, Epstein‐Barr virus, herpes simplex viruses, hepatitis C virus, and HIV. Increasingly, viral infections have been diagnosed using an oral sample (e.g. saliva mucosal transudate or an oral swab) instead of blood or urine. The results of two studies using a rapid and semi‐quantitative lateral flow assay format demonstrating the correlation of HIV anti‐IgG/sIgA detection with saliva and serum samples are presented. When immediate detection of infection is important, point‐of‐care devices that obtain a non‐invasive sample from the oral cavity can be used to provide a first line diagnosis to assist in determining appropriate counselling and therapeutic path for an increasing number of diseases.

Immunoprevalence to Six Waterborne Pathogens in Beachgoers at Boquerón Beach, Puerto Rico: Application of a Microsphere-Based Salivary Antibody Multiplex Immunoassay

Waterborne infectious diseases are a major public health concern worldwide. Few methods have been established that are capable of measuring human exposure to multiple waterborne pathogens simultaneously using non-invasive samples such as saliva. Most current methods measure exposure to only one pathogen at a time, require large volumes of individual samples collected using invasive procedures, and are very labor intensive. In this article, we applied a multiplex bead-based immunoassay capable of measuring IgG antibody responses to six waterborne pathogens simultaneously in human saliva to estimate immunoprevalence in beachgoers at Boquerón Beach, Puerto Rico. Further, we present approaches for determining cutoff points to assess immunoprevalence to the pathogens in the assay. For the six pathogens studied, our results show that IgG antibodies against antigens from noroviruses GI.I and GII.4 were more prevalent (60 and 51.6%, respectively) than Helicobacter pylori (21.4%), hepatitis A virus (20.2%), Campylobacter jejuni (8.7%), and Toxoplasma gondii (8%) in the saliva of the study participants. The salivary antibody multiplex immunoassay can be used to examine immunoprevalence of specific pathogens in human populations.

Nasal self-swabbing for estimating the prevalence of Staphylococcus aureus in the community

Staphylococcus aureus remains a significant cause of morbidity and mortality and, therefore, a burden on healthcare systems. Our aim was to estimate the current rate of nasal S. aureus carriage in the general population and to determine the feasibility of nasal self-swabbing as a means of detection. Two thousand people (1200 adults and 800 children) from a single NHS general practice in Southampton, UK, were randomly selected from a general practice age sex register, stratified by age and sex, and invited to undertake nasal self-swabbing in their own home. Overall, 362 (32.5%) swabs from adults and 168 (22%) from children were returned. Responses were greater for adults and those of increased age, female gender and decreasing socio-economic deprivation. The overall estimated practice carriage rate of S. aureus directly standardized for age sex was 28% [95% confidence interval (CI) 26.1-30.2%]. Carriage of meticillin-susceptible S. aureus was 27% (95% CI 26.1-30.2%), whilst that of meticillin-resistant S. aureus was 1.9% (95% CI 0.7-3.1%). Although nasal self-swabbing rates were relatively low, they are comparable to other studies and may allow large population-based carriage studies to be undertaken at relatively low cost. Importantly, this study updates prevalence data for S. aureus carriage in the community.

Oral fluid and hepatitis A, B and C: a literature review

BACKGROUND AND AIMS

Viral hepatitis is a significant global health problem that, depending upon the virus, affects individuals of the developing and/or developed world. In recent years, there has been renewed interest in whether oral fluids can be considered as a source of viral hepatitis transmission and whether oral fluid, in particular, whole saliva, may be a useful source for viral detection as part of the diagnosis and monitoring of viral hepatitis. The aim of this article was to review current data concerning the possible carriage of the hepatitis A, B and C viruses within saliva and gingival crevicular fluid. Such knowledge will indicate if (i) oral fluid is a possible source of infection and (ii) whether oral fluid can be used for diagnosis and monitoring of viral hepatitis.

DATA AND SOURCES

A literature search was conducted using PubMed (Medline), EMBASE/Excerpta medica, the Cochrane database and Scopus. The results were limited to published material after 2000. Relevant material was evaluated and reviewed.

CONCLUSION

There is some evidence that hepatitis viruses A, B and C are present in oral fluids, particularly whole saliva and gingival crevicular fluid and may thus be possible sources of viral detection in clinical diagnosis and monitoring. However, the data are inconsistent and warrant the need for well-planned longitudinal studies to explore the precise frequency of oral carriage of such viruses and to determine the virological and host factors that may influence the oral presence of hepatitis A, B and C viruses.

Feasibility of collecting oral fluid samples in the home setting to determine seroprevalence of infections in a large-scale cohort of preschool-aged children

Oral fluid is a non-invasive biological sample, which can be returned by post, making it suitable for large-scale epidemiological studies in children. We report our experience of oral fluid collection from 14 373 preschool-aged children in the UK Millennium Cohort Study. Samples were collected by mothers in the home setting following the guidance of trained interviewers, and posted to the laboratory. Samples were received from 11 698 children (81.4%). Children whose mothers were of Black Caribbean ethnicity and who lived in non-English-speaking households were less likely to provide a sample, and those with a maternal history of asthma more likely to provide a sample [adjusted risk ratio (95% CI) 0.85 (0.73-0.98), 0.87 (0.77-0.98) and 1.03 (1.00-1.05) respectively]. Collection of oral fluid samples is feasible and acceptable in large-scale child cohort studies. Formal interpreter support may be required to increase participation rates in surveys that collect biological samples from ethnic minorities.

Participant-collected, mail-delivered oral fluid specimens can replace traditional serosurveys: a demonstration-of-feasibility survey of hepatitis A virus-specific antibodies in adults

BACKGROUND

Although population-based serosurveys offer an optimal measure of cumulative infection rates, they are seldom performed due to high cost and complex logistics. Use of participant self-collected oral fluid as a diagnostic specimen and mail for specimen delivery has the potential of generating reliable, population-representative data at limited cost.

METHODS

A survey of oral fluid HAV-specific immunoglobulin G (an indicator of past HAV infection) was undertaken in a provincially representative sample of 20-39 year olds as a pilot study. A provincial administrative database served as the sampling frame. Potential participants were invited by mail to collect oral fluid and complete a questionnaire at home and return both by mail. Additional telephone prompting was directed at slow responders. Oral fluid was tested using a validated ELISA.

RESULTS

From among 2,448 potential participants, contact by mail or telephone was made with 1,009 eligible subjects; 59% (585) participated. Materials withstood mailing and the quality of self-collected specimens was excellent. A positive test result was found in 22.1% overall and in 15.7% of self-reported non-vaccinated subjects. Among Canadian-born, non-vaccinated individuals, the positive test rate increased progressively from 1.2% (95% CI: 0-6.3) in 20-24 year olds to 16.4% (95% CI: 9.5-23.3) in 35-39 year olds. Antibody prevalence was higher among Canadian-born non-immunized 20-29 year olds who reported travel to developing countries (33.3%, 95% CI: 11.6-55.1) than in non-travellers (2.5%, 95% CI: 0.7-6.2).

CONCLUSIONS

Mail-based population surveys of infection markers in oral fluid are feasible provided an appropriate sampling frame is used. This survey revealed a high anti-HAV antibody prevalence in young Canadian adults, increasing with age and travel to developing countries.

Stability of plasma analytes after delayed separation of whole blood: implications for epidemiological studies

BACKGROUND

Large blood-based epidemiological studies require simple, cost-effective sample collection methods. Immediate sample separation or rapid transport of chilled blood samples to a central laboratory may be impractical or prohibitively expensive. To assess the feasibility and reliability of transporting blood samples over several days at ambient temperature (e.g. by mail), we evaluated the stability of various plasma analytes in samples stored at room temperature or chilled.

METHODS

Multiple vacutainers of blood, containing EDTA and aprotinin as preservative, were drawn from 12 volunteers and stored at 21 degrees C or 4 degrees C. Immediately after collection and 1, 2, 3, 4, and 7 days later, vacutainers stored at each temperature were centrifuged, and the plasma was aliquoted and stored at -80 degrees C. Subsequently, all aliquots from each individual were analysed in one analytical run for a range of chemistries.

RESULTS

In whole blood stored at room temperature for up to 7 days, concentrations of albumin, apolipoproteins A1 and B (apoA1 and apoB), cholesterol, high density lipoprotein (HDL), total protein, and triglycerides changed by less than 4%, and low density lipoprotein (LDL) by less than 7%. Whilst alanine transaminase (ALT), creatine kinase (CK), creatinine, and gamma-glutamyl transferase (GGT) concentrations changed substantially at room temperature, there was less than 4% change during chilled storage up to 7 days. By contrast, aspartate transaminase (AST) concentrations increased markedly under both conditions.

CONCLUSIONS

A wide range of important analytes, including lipids, change by only a few per cent in whole blood during storage at room temperature for several days. Mailed transport of whole blood samples may, therefore, be a simple and cost-effective option for large-scale epidemiological studies.

Stability of total and rubella-specific IgG in oral fluid samples: the effect of time and temperature

Oral fluid (saliva) samples are increasingly used as a minimally invasive alternative to serum to detect antibody for viral diagnostics and population-based surveys of immunity to common infections. Postal collection of these samples is convenient, but it is uncertain how oral fluid antibody levels may deteriorate during transit. In this study multiple oral fluid samples, from a group of individuals, were collected and kept at two different temperatures (10 and 20 degrees C, simulating winter and summer conditions ) for periods of up to 7 days. They were then tested for total immunoglobulin G (IgG) and for rubella-specific IgG. Total IgG concentrations ranged from 2.0 to 48.6 mg/l but showed no significant decrease over the 7-day period. There was also no significant change in rubella-specific IgG measured using an antibody capture ELISA, but testing with an indirect rubella IgG ELISA revealed a significant decrease in absorbance values between day 1 and day 7 at 20 degrees C. The difference in the rubella assay results may reflect the different assay formats with the signal in the indirect procedure related to the concentration of rubella IgG in the oral fluid sample, rather than the proportion of virus-specific IgG measured with the antibody capture format. The study demonstrated that total and rubella specific IgG in oral fluid samples were stable for up to 7 days at differing temperatures and that an antibody capture assay format should be used for virus-specific testing to minimise inaccurate results due to low IgG concentrations in oral fluid samples.