Potential public health benefits from cat eradications on islands

Cats ( Felis catus ) are reservoirs of several pathogens that affect humans, including Toxoplasma gondii . Infection of pregnant women with T . gondii can cause ocular and neurological lesions in newborns, and congenital toxoplasmosis has been associated with schizophrenia, epilepsy, movement disorders, and Alzheimer’s disease. We compared seroprevalence of T . gondii and risk factors in people on seven islands in Mexico with and without introduced cats to determine the effect of cat eradication and cat density on exposure to T . gondii . Seroprevalence was zero on an island that never had cats and 1.8% on an island where cats were eradicated in 2000. Seroprevalence was significantly higher (12–26%) on the five islands with cats, yet it did not increase across a five-fold range of cat density. Having cats near households, being male and spending time on the mainland were significant risk factors for T . gondii seroprevalence among individuals, whereas eating shellfish was protective. Our results suggest that cats are an important source of T . gondii on islands, and eradicating, but not controlling, introduced cats from islands could benefit human health.