Bovine fascioliasis

economic impact and control in Gulf Coast cattle based on seasonal transmission

Abstract

In the United States, Fasciola hepatica is found primarily in Gulf Coast and western states with evidence of increasing prevalence associated with irrigated pastures. Direct loss from the condemnation of livers in 1981 was $7.2 million. Losses from lowered weight gain in subclinical infections were not estimated. Epidemiological studies in Louisiana revealed that most transmission to cattle occurred in the spring and early summer. Annual variation in the number of flukes transmitted was correlated with climatic variables determining the number of snail intermediate hosts available for infection. Herd prevalence and sentinel calf data suggest that annual autumnal treatment with albendazole was effective for sustained reduction of fluke burdens in low risk years, but at least two treatments are required in high risk years. Feedlot studies indicate that albendazole treatment may improve average daily gain and feed efficiency in infected feeder calves. Beef herd performance was improved by treatment directed at reducing loss of cow condition during winter. Further studies to develop more cost effective strategic control measures are recommended.