Optimization of Raccoon latrine surveys for quantifying exposure to Baylisascaris procyonis.

Raccoon (Procyon lotor) latrine surveys are an efficient and cost-effective method to quantify Baylisascaris procyonis exposure risk for intermediate hosts. Nevertheless, current methodologies may introduce bias by homogenizing scats collected within latrines and estimating exposure risk at the latrine scale. The objective of this study was to examine the potential for raccoon latrine size to bias estimates of risk of exposure when utilizing current methodologies that pool scats prior to analysis. We accomplished this by evaluating correlation of the presence of B. procyonis eggs among scats collected within latrines. Specimens were collected in southern Indiana during November and December of 2006. Raccoon scats collected within latrines exhibited no correlation with the presence of B. procyonis eggs. Accordingly, to eliminate the bias introduced by pooling scats within latrines, scats rather than latrines should be treated as the sampling unit for estimating risk of exposure for intermediate hosts. Further, evaluation of exposure risk based on individual scats has the potential to greatly reduce the time and expense associated with obtaining precise estimates of B. procyonis exposure risk.