Evaluation of the German cockroach (Blattella germanica) as a vector for verotoxigenic Escherichia coli F18 in confined swine production.

German cockroaches are common pests of confined swine production in North Carolina and other southeastern states. Vector competence of German cockroaches for one of the most important porcine bacterial pathogens, verotoxigenic Escherichia coli F18, was evaluated in laboratory bioassays using a culturing approach followed by multiplex PCR. In addition, the populations of fecal coliforms from the feces of piglets and cockroaches collected from a swine nursery were assessed. Viable and virulent cells of E. coli F18 were detected in cockroach feces for up to 8 days after the initial exposure. The population of fecal coliforms in cockroach feces was high (4.4 x 10(5) CFU g(-1)) and comparable to that of piglet feces (1.9 x 10(6) CFU g(-1)). This study demonstrates that cockroaches may serve as important mechanical vectors of pathogenic E. coli. Integrated management of cockroach populations should be incorporated into the disease prevention and control programs in the swine industry.