Prevalence of Fasciola hepatica infection in native mammals in southeastern Australia.

Fasciola hepatica infection was found in 5 of 12 marsupial and 1 of 3 eutherian species examined in southeastern Australia. Prevalence of infection in native mammals was as follows: Macropus giganteus, 59%; M. rufogriseus banksianus, 15%; Wallabia bicolor, 5%; Vombatus ursinus, 30%; Trichosurus vulpecula, 5%; and Rattus fuscipes, 4%. Collection sites were assigned to one of two categories. Prevalence was higher in macropodids collected on agricultural pastures grazed by sheep and cattle (category A) than in macropodid collected in forested areas variably grazed by livestock (category B). A high prevalence of infection (82%) was recorded in M. giganteus in an area from which sheep and cattle had been excluded for 15 years. Prevalence of F. hepatica infection in V. ursinus was similar in the two habitat categories; however, within forested areas infection was more common in V. ursinus collected near swamps and creeks than those taken from drier ridges. The presence of habitat suitable for the snail intermediate host. Lymnaea tomentosa, and utilization of this habitat by domestic and native mammals are important epidemiological factors. Moderate numbers of flukes (1-95) and faecal egg production (1-195 eggs per gram of faeces (EPG)) in M. giganteus and M.r. banksianus emphasize their suitability as hosts and contaminators of pasture. Small numbers of flukes and conspicuous hepatic lesions in V. ursinus suggest moderate resistance to infection. The low prevalence and small number of flukes in T. vulpecula was attributed to the arboreal habit of this host. R. fuscipes is susceptible to infection but infected individuals were found in only one of numerous forest areas with suitable snail habitat. Feeding behaviour is probably responsible for the absence of F. hepatica infection in W. bicolor and Rattus lutreolus in forested areas.