Prevalence of Fascioloides magna in cattle and deer in Michigan.

A survey among 1.12 million cattle slaughtered in 357 packing plants in Michigan during 1977 to 1981 was conducted to determine the prevalence of liver fluke infection. The condemnation rate of liver fluke-infected livers was 0.41, 3.7, and 13.9% in the southern, northern-lower, and upper regions of Michigan, respectively. The same trend in infection rates was observed in white-tailed deer that had been examined in diagnostic laboratories in the state. A serologic survey among 50 randomly selected dairy farms detected Fascioloides antibody-carrying cattle in 3 farms. The data on prevalence in slaughter cattle were slightly biased, because many slaughter cattle originated from other states in which F magna may be less common.