Assessing Potential Environmental Contamination by Baylisascaris procyonis Eggs from Infected Raccoons in Southern Texas.

Baylisascaris procyonis is a large ascarid of raccoons (Procyon lotor) and is a zoonotic threat. We documented the potential rate a raccoon population can contaminate their environment with B. procyonis eggs. We estimated the population size of raccoons using a 9 × 7 trapping grid of Havahart traps, identified locations of raccoon scats through systematic searches, and enumerated the distance B. procyonis eggs passively travel from site of origin upon scat decay. During an 8-week capture period, the raccoon population was estimated to be 19.6 ± 1.3 raccoons within the 63-ha study area (1 raccoon/3.2 ha). There were 781 defecation sites, of which 744 (95.3%) were isolated sites and 37 (4.7%) were latrine sites. Fifty-three (6.8%) defecation sites occurred in areas associated with human structures (commensal zone). Of the noncommensal sites, 9 (1.2%) and 719 (98.8%) sites were identified as latrine sites and isolated scats, respectively. More latrine sites were located within the commensal zone (p < 0.0001, [Formula: see text]) than proportionately available space. Twenty-five raccoon scats containing B. procyonis eggs were allowed to decay on level bare soil by way of simulated rain events, 13 were allowed to desiccate naturally in the environment, and 12 were allowed to desiccate and, subsequently, experience a simulated 1 cm rain event; eggs were found 49 ± 6, 28 ± 8, and 68 ± 8 cm from the initial scat location, respectively. We calculated that a single B. procyonis-infected raccoon could contaminate 0.03 ± 0.01 ha/year with B. procyonis eggs. Our findings indicate that B. procyonis represents a substantial risk to humans in areas where infected raccoons and humans co-occur.