ROLE OF PEST FILTH FLIES IN THE AGRO-ECOLOGY AND EPIDEMIOLOGY OF SHIGA-TOXIGENIC E. COLI O157, O111, AND O26 IN CATTLE

The project goal is to describe and analyze the agro-ecologic inter-relationships between bovine shiga-toxigenic E. coli (STEC) fecal shedding and hide surface contamination and synanthropic muscoid fly STEC occurrence and fly population densities in dairy and beef cattle operations in multiple states. There are three related research objectives to address this goal: (1) To measure the summer point prevalence of STEC O157, O111, and O26 in feces and on hides of cattle and in locally abundant muscoid pest fly populations (primarily house, stable, and horn flies) and concurrently estimate fly population densities on 60 dairy and beef (feedlot and cow-calf) farms; (2) To determine the agro-ecologic inter-relationships between pest flies, cattle, and STEC O157, O111, and O26 by intensively monitoring fly population densities and fly and cattle STEC occurrence on four Nebraska and two Tennessee cattle farms over two years (cohort [time trend] study); and (3) To measure
effects of total pest fly exclusion on natural STEC O157 intestinal infection and hide contamination in small groups of confined Nebraska beef cattle from winter weaning until fall sale for slaughter (intervention trial).