Salivary Antibody Responses to Potentially Waterborne and Environmentally Transmitted Infections Among Two Tribal Nations in the Southwest United States.

Purpose: Tribal Nations disproportionately lack access to safe drinking water and can be adversely affected by other water quality and environmental 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 Tribal Nation annual festivals and tested them for salivary immunoglobulin G (IgG) responses to selected common infections using an in-house multiplex immunoassay. Antibody responses were compared to responses from a previously conducted study in the midwestern United States.

Methods: We collected and tested 531 samples from Tribal Nation sites and used data on 453 previously analyzed samples from the Midwest site. Logistic and linear regression models were used to model a binary classification of seropositivity and the intensity of the antibody response, respectively.

Results: Seroprevalence of chronic infections (Helicobacter pylori and Toxoplasma gondii) were generally consistent with estimates from population-based studies. Compared to the Midwest site, one of the Tribal Nation sites had consistently higher median antibody responses to several noroviruses. The Tribal Nation sites had a lower seroprevalence of hepatitis E virus antibodies. At the Tribal Nation sites, farm residents had higher antibody responses to Cryptosporidium spp., bottled water consumption was associated with lower responses to Cryptosporidium spp., animal contact was associated with T. gondii seropositivity, and recent diarrhea was associated with higher norovirus antibody responses. Helicobacter pylori seropositivity was associated with reduced odds of reporting allergies.

Conclusion: This study demonstrated the application of a multiplex salivary immunoassay in Tribal Nations to provide insights regarding selected common pathogens which are transmitted through different transmission pathways including person-to-person contacts, contaminated food, soil and drinking water.