Seroprevalence of Naegleria fowleri in the Houston-Galveston Texas Population.

Naegleria fowleri is a free-living amoeba and the causative agent of Primary Amebic Meningoencephalitis (PAM), a rare yet almost always fatal disease that primarily affects children. While only 431 PAM cases have been reported worldwide, the southern states of the United States, including Texas, report the highest number of cases. Despite the high mortality of the disease, studies have identified antibodies to N. fowleri in healthy individuals suggesting that exposure to this pathogen is common, but disease is rare. Here, we investigated the seroprevalence of N. fowleri in the general population of individuals residing in an area of Texas to identify population characteristics or water-based activity levels that may be associated with seropositivity. For this, healthy human participants were surveyed, and blood samples were collected to test their sera against N. fowleri lysate by indirect ELISA. A seropositivity rate of 89% was observed with 40% of participants demonstrating a titer of up to 1:500. Demographic and water-activity level differences among subjects did not correlate with antibody titers. The high seropositivity suggests environmental exposure and the development of humoral immunity against this pathogen.