A Community Study of Drinking Water Supply and Gastroenteritis in Puerto Rico: Application of a Salivary Immunoassay for Detection of Waterborne Infection
Waterborne illness presents public health and economic challenges to communities with limited resources and impaired infrastructure. In Puerto Rico (PR), approximately one third of the 240 drinking water systems not served by the PR Aqueduct and Sewer Authority (PRASA) offer little to no treatment. An ongoing prospective intervention study in three non-PRASA communities aims to evaluate public health benefits of low-cost, sustainable water treatment technologies by comparing rates of infections before and after introduction of filtration and reliable disinfection. This study involves the detection of pathogens in stool samples obtained from users of the small public water supply systems, using the Luminex Gastrointestinal Pathogen Panel kit, and analysis of saliva samples for antibody responses to waterborne pathogens, including noroviruses and Cryptosporidium, using an in-house multiplex Luminex immunoassay. Salivary antibody testing is a non-invasive, easy-to-collect, and inexpensive alternative to serological testing. In the pre-intervention phase, 97 stool and 90 saliva samples were collected from community members along with information regarding self-report of gastroenteritis symptoms. Preliminary results show that nine (9.3%) participants shed pathogens in stool, including enterotoxigenic E. coli, Salmonella, Shigella, adenoviruses, noroviruses, Cryptosporidium, Giardia, and Entamoeba histolytica. Additionally, there was a significant association between self-reported diarrhea and strong (>90th percentile) IgG antibody responses to GII.9 noroviruses (OR: 6.54, 95%CI: 1.55 – 27.67, p=0.01). The post-intervention phase is expected to begin in summer 2023. Results of this work help to prioritize risks and inform decisions regarding water supply and treatment that may improve the health and welfare of non-PRASA communities in PR.