Spatial epidemiology of Toxoplasma gondii seroprevalence in sentinel feral chickens (Gallus gallus) in Kaua'i, Hawai'i

Toxoplasma gondiiis a globally prevalent coccidian parasite that fatally infects a wide range of endangered avian and mammalian hosts in Hawai'i including the Hawaiian Monk Seal (llio holo I ka uaua;Monachus schauinslandi), Hawaiian Goose (Nene;Branta sandvicensis) and Hawaiian Crow ('Alala;Corvus hawaiiensis). Thus, identifying environmental factors that predict or impactT. gondiiexposure is important for mitigating disease risks. The island of Kaua'i is a good model system to study spatial and environmental covariates ofT. gondiiprevalence due to (1) high landscape heterogeneity spanning a small geographical area, (2) the presence of an ideal sentinel species, the feral chicken (Gallus gallus), and (3) recent evidence thatT. gondiicontributes to local declines of Hawai'i's endemic bird and mammal species. Despite these compelling opportunities, little is known about the prevalence or distribution ofT. gondiiin Hawai'i. In this study, 294 Kaua'i feral chickens were tested forT. gondiiusing ELISA IgG immunoassays, of which 117 chickens (39.8%) tested seropositive - indicating infection with the parasite - and nearly every sampled site contained chickens with positive seroprevalence. Prevalence varied among the 34 sampled localities and was significantly, positively correlated with proximity to the coast. These findings reveal thatT. gondiiis prevalent across Kaua'i. Furthermore, this variability offers insight to the factors that might predictT. gondiiseropositivity across the landscape, and likewise predict exposure risks for endangered wildlife.