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

Family income and exposure to norovirus in childhood: Findings from the UK Millennium Cohort Study

Children from low income families are at greater risk of poorer health outcomes than their wealthier peers. Hospital admissions for children with gastroenteritis increase as deprivation increases. Noroviruses are responsible for 47-96% of outbreaks of acute paediatric gastroenteritis, and 5-36% of sporadic cases worldwide. However, evidence on the relationship between family income and childhood exposure to norovirus is still limited, with published studies pointing to conflicting results. This study explored the relationship between family income and early childhood exposure to norovirus in the United Kingdom using data from the Millennium Cohort Study linked to serological data. Exposure to norovirus was measured by the level of human norovirus-specific antibodies (titres) obtained from oral fluid samples collected from 5962 pre-school age UK children and tested for Norovirus-specific Immunoglobulin G (IgG). Multivariable linear and quantile regression analyses were conducted to investigate the extent to which family income was associated with child norovirus exposure, and to explore the potential mechanisms through which income might translate into norovirus exposure. Higher norovirus-specific IgG titres were associated with higher family income, but the relationship weakened after controlling for potential mediating factors, mainly increased opportunities for person-to-person contacts, such as formal childcare arrangements. This study provides novel evidence that can help inform and prioritise policy interventions (e.g. vaccination) and health promotion programmes to reduce child health inequalities in the area of gastrointestinal infections.

The role of the early social environment on Epstein Barr virus infection: a prospective observational design using the Millennium Cohort Study

Epstein-Barr virus (EBV) is a highly prevalent herpesvirus linked to infectious mononucleosis and several malignancies. This paper aims to study the association between children's early life social environment at 9 months and EBV infection at 3 years of age.

METHODS

We used data on children included in the UK Millennium Cohort Study. We described the social environment using area-level and material factors as well as socioeconomic position (SEP) at 9 months. EBV was measured at 3 years of age (n = 12 457).

RESULTS

Lower rates of EBV infection were observed in children living in towns and rural areas compared with those living in cities. Lower SEP and overcrowding in the household increased the odds of being infected. Children whose parents were social tenants were more likely to be infected than homeowners. In the overall model, the strength of the association between material factors and EBV infection weakened.

CONCLUSIONS

We showed that early life material deprivation was associated with a higher risk of EBV infection among 3-year-olds. Children living in more deprived social conditions may be more likely to become EBV carriers at an earlier age.

Application of Oral Fluid Assays in Support of Mumps, Rubella and Varicella Control Programs

Detection of specific viral antibody or nucleic acid produced by infection or immunization, using oral fluid samples, offers increased potential for wider population uptake compared to blood sampling. This methodology is well established for the control of HIV and measles infections, but can also be applied to the control of other vaccine preventable infections, and this review describes the application of oral fluid assays in support of mumps, rubella and varicella national immunization programs. In England and Wales individuals with suspected mumps or rubella, based on clinical presentation, can have an oral fluid swab sample taken for case confirmation. Universal varicella immunization of children has led to a drastic reduction of chickenpox in those countries where it is used; however, in England and Wales such a policy has not been instigated. Consequently, in England and Wales most children have had chickenpox by age 10 years; however, small, but significant, numbers of adults remain susceptible. Targeted varicella zoster virus (VZV) immunization of susceptible adolescents offers the potential to reduce the pool of susceptible adults and oral fluid determination of VZV immunity in adolescents is a potential means of identifying susceptible individuals in need of VZV vaccination. The main application of oral fluid testing is in those circumstances where blood sampling is deemed not necessary, or is undesirable, and when the documented sensitivity and specificity of the oral fluid assay methodology to be used is considered sufficient for the purpose intended.

Detection of Porcine reproductive and respiratory syndrome virus (PRRSV) antibodies in oral fluid specimens using a commercial PRRSV serum antibody enzyme-linked immunosorbent assay

The purpose of the present study was to evaluate the diagnostic performance of a commercial serum antibody enzyme-linked immunosorbent assay (ELISA) modified to detect anti-Porcine reproductive and respiratory syndrome virus (PRRSV) antibodies in pen-based oral fluid specimens. Experimental and field oral fluid samples of defined status in reference to exposure of swine with PRRSV were used to derive the kinetics of detectable concentrations of antibody against PRRSV. Immunoglobulin (Ig)M and IgA were readily detected in oral fluid specimens from populations in which PRRSV infection was synchronized among all individuals but not in samples collected in commecial herds. In contrast, IgG was readily detected at diagnostically useful levels in both experimental and field samples for up to 126 days. Estimates of the IgG oral fluid ELISA performance were based on results from testing positive oral fluid samples (n = 492) from experimentally inoculated pigs (n = 251) and field samples (n = 241) and negative oral fluid samples (n = 367) from experimentally inoculated pigs (n = 84) and field samples (n = 283). Receiver operating characteristic analysis estimated the diagnostic sensitivity and specificity of the assay as 94.7% (95% confidence interval [CI]: 92.4, 96.5) and 100% (95% CI: 99.0, 100.0), respectively, at a sample-to-positive ratio cutoff of ≥0.40. The results of the study suggest that the IgG oral fluid ELISA can provide efficient, cost-effective PRRSV monitoring in commercial herds and PRRSV surveillance in elimination programs.

Efficient surveillance of pig populations using oral fluids

Currently virus surveillance in swine herds is constrained by the cost-effectiveness and efficiency of sampling methods. The objective of this study was to assess the value of using oral fluids collected by barn personnel as a method of surveillance based on PCR testing. Approximately 12,150 pigs in 10 wean-to-finish barns on 10 farms were monitored for the presence of porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), influenza A virus (IAV), and Torque teno virus genogroups 1 (TTV1) and 2 (TTV2) by sampling oral fluid specimens. Oral fluid samples were collected from 6 pens at each site starting at the time of pig placement (∼3 weeks of age) and continuing thereafter at 2-week intervals for a period of 18 weeks. Data were analyzed both on a pen basis and barn basis. Overall, 508 (85%) samples were positive for PCV2, 73 (12%) for PRRSV, 46 (8%) for IAV, 483 (81%) for TTV2, and 155 (26%) for TTV1 during the study period. The estimated arithmetic means of the quantitative PCR-positive oral fluids for PCV2, PRRSV, and IAV were 1×10(4.62), 1×10(4.97), and 1×10(5.49)per ml. With a single exception, all barns were positive for PCV2 and TTV2 at every sampling point in the study. Virus detection varied among barns, particularly for IAV and PRRSV. The pen level, cumulative distribution of agent combinations between all 10 barns were statistically different. The most commonly observed patterns were PCV2+TTV2 (239 pen samples, 40%), PCV2+TTV1+TTV2 (88 pen samples, 15%), and PCV2 alone (66 pen samples, 11%). This "proof-of-concept" project showed that a variety of viruses could be detected either intermittently or continuously in pig populations and demonstrated that barn herd virus status is highly variable, even among barns in the same production system. Oral fluid sampling is a promising approach for increasing the efficiency and cost effectiveness of virus surveillance in swine herds.

The storage and use of biological tissue samples from minors for research: a focus group study

Genetic research on pediatric stored tissue samples raises specific ethical questions that differ from those raised when adults are the donors. To investigate opinions on this matter, we conducted 10 focus group discussions. Five focus groups were conducted with adult participants and 5 had teenage participants between 15 and 19 years old. The discussions were analyzed with NVIVO 8 (qualitative research software). We found the following recurrent categories: the requirement that research should not pose any burden on children and that it should benefit other children, the trust people had in the role of parents, the need for information and the growth towards autonomy. Both the adults and teenagers we interviewed thought that the inclusion of tissue samples from minors in research had ethical implications. A major concern was that nontherapeutic research would pose no extra burden on children, which would assume the use of nonintrusive methods of gathering samples and the use of samples that were gathered in a diagnostic context. Participants, however, also understood the necessity of such research. The overall impression was that parents would be the best persons to make decisions on behalf of a small child and that the same parents would engage their children in the decision-making when they grew older. People thought that there was a duty to recontact minors when they reached the age of competence but on a best-effort basis.