Visitors to a Tropical Marine Beach Show Evidence of Immunoconversions to Multiple Waterborne Pathogens

Abstract

Determining infections from environmental exposures, particularly from waterborne pathogens is a challenging proposition. The study design must be rigorous and account for numerous factors including study population selection, sample collection, storage, and processing, as well as data processing and analysis. These challenges are magnified when it is suspected that individuals may potentially be infected by multiple pathogens at the same time. Previous work demonstrated the effectiveness of a salivary antibody multiplex immunoassay in detecting the prevalence of immunoglobulin G (IgG) antibodies to multiple waterborne pathogens and helped identify asymptomatic norovirus infections in visitors to Boquerón Beach, Puerto Rico. In this study, we applied the immunoassay to three serially collected samples from study participants within the same population to assess immunoconversions (incident infections) to six waterborne pathogens: Helicobacter pylori, Campylobacter jejuni, Toxoplasma gondii , hepatitis A virus, and noroviruses GI. I and GII.4. Further, we examined the impact of sampling on the detection of immunoconversions by comparing the traditional immunoconversion definition based on two samples to criteria developed to capture trends in three sequential samples collected from study participants. The expansion to three samples makes it possible to capture the IgG antibody responses within the survey population to more accurately assess the frequency of immunoconversions to target pathogens. Based on the criteria developed, results showed that when only two samples from each participant were used in the analysis, 25.9% of the beachgoers immunoconverted to at least one pathogen; however, the addition of the third sample reduced immunoconversions to 6.5%. Of these incident infections, the highest levels were to noroviruses followed by T. gondii . Moreover, many individuals displayed evidence of immunoconversions to multiple pathogens. This study suggests that detection of simultaneous infections is possible, with far reaching consequences for the population. The results may lead to further studies to understand the complex interactions that occur within the body as the immune system attempts to ward off these infections. Such an approach is critical to our understanding of medically important synergistic or antagonistic interactions and may provide valuable and critical information to public health officials, water treatment personnel, and environmental managers.

Salivary Antibodies against Multiple Environmental Pathogens Found in Individuals Recreating at an Iowa Beach

“…This study followed a similar sampling protocol and analytical design to previously conducted studies. In brief, this study used a multiplex Luminex platform to detect salivary antibody responses to antigens (Ag) as shown in Table 1 [ 6 , 13 , 15 , 16 ]. Table 1 provides information on the organism, antigen, source of where the antigen was purchased/acquired, and the amount of antigen coupled to the beads.…”

“…In previous work, we described the development and utility of salivary antibody multiplex immunoassays in measuring symptomatic and asymptomatic infections, immunoprevalence, coinfections and incident infections associated with recreating in contaminated waters and other environmental and water-related exposures [ 13 , 14 , 15 , 16 , 17 , 18 ]. These research efforts demonstrated that the immunoassays could provide cost and time savings in comparison to traditional enzyme-linked immunosorbent assays (ELISAs) as more analytes are added to the assay [ 18 , 19 ].…”

Rapid Salivary IgG Antibody Screening for Hepatitis A

“…Cutoff criteria were established in reference 32 [cutoff ϭ 10 mean (h) ϩ 3 SD (h) , where h ϭ log 10 (MFI of control beads)] to distinguish immunopositive and immunonegative samples and employed to measure immunopositivity and immunopreva- lence (baseline immunopositivity) in the population. Immunoconversions are defined using the more stringent three-sample criterion presented by Simmons et al (33), which extends the traditional 4-fold increase from S1 to S2 definition to ensure that the S2 sample is immunopositive (MFI Ն cutoff point) and accounts for the fact that IgG levels are expected to remain relatively high and not drop to zero during the 30-to 40-day period after initial exposure; accordingly, the immunoconversion criteria are S2 Ն 4 ϫ S1, S2 Ն cutoff, and S3 Ն 3 ϫ S1. Immunoconversions were computed only for study participants who provided all three samples.…”

“…Our team developed a bead-based, multiplex salivary antibody immunoassay to measure the prevalence of antibodies to multiple waterborne pathogens associated with drinking and recreational water contamination simultaneously (30,31). Application of the assay has allowed us to measure immunoprevalence (32), immunoconversions (incident infections), coinfections (33), and asymptomatic infections (34) from exposure to various waterborne pathogens in visitors to Boquerón Beach, Puerto Rico. Immunoprevalence (the prevalence of circulating antibodies against specific pathogens) is an important aspect of these studies because it affords the ability to capture the baseline level of exposure at the beginning of a longitudinal study.…”

Editorial: Environment and Health

“…In 2016 WHO reported that globally some 12.6 million deaths each year can be ascribed to unhealthy environments. Moreover, 24% of global deaths (and 28% of deaths among children under five) come from modifiable environmental factors (Prüss-Ustün et al, 2016). Human epidemiological studies and experiments in laboratory animals proved that exposure to some pollutants can increase susceptibility to diseases such as diabetes, heart disease, and reproductive cancers.…”