Salivary antibody responses to waterborne and environmental infections among Two Tribal Nations in the Southwest United States
Tribal Nations disproportionately lack access to safe drinking water and can be adversely affected by other water quality concerns. Such conditions could lead to an increase in the transmission of waterborne, environmental and hygiene-related infections. We collected saliva samples from attendees at two Oklahoma Tribal Nation annual festivals and tested them for salivary immunoglobulin G (IgG) responses to selected common chronic and transient infections using a previously developed in-house multiplex immunoassay on a Luminex platform. Antibody responses from two Tribal Nations were compared to responses from participants in a previously conducted study in the midwestern United States. Logistic and linear regression models were used to model a binary classification of seropositivity (for long-term, chronic infections or infections causing a long-term antibody response) and the intensity of the antibody response (for acute transient infections), respectively, across these three populations, and by demographic, sanitation and drinking water quality features for the two Tribal Nations. We collected and tested a total of 531 samples from the Tribal Nation sites and used data on 453 previously analyzed samples from the Midwest site. Seroprevalence of chronic infections (cytomegalovirus or CMV, Helicobacter pylori and Toxoplasma gondii) were generally consistent with previous estimates from population-based studies. Compared to the Midwest site, the Tribal Nation sites had higher median antibody responses to several noroviruses and lower median antibody responses to Campylobacter. The Tribal Nation sites had significantly lower seroprevalence rates of Hepatitis E virus and one of the sites had lower seroprevalence of T. gondii compared to the Midwest site. At the two Tribal Nation sites, current farm residents had higher antibody responses to Cryptosporidium spp., animal contact was associated with T. gondii seropositivity and recent diarrhea was associated with higher norovirus antibody responses. CMV and Helicobacter pylori seropositivity were associated with reduced odds of reporting allergies. This study demonstrated the application of a non-invasive salivary immunoassay to assess risk factors for waterborne and environmentally transmitted infections.