Domestic sheep as a rare definitive host of the large American liver fluke Fascioloides magna.

Two domestic sheep were inoculated orally with 250 metacercariae of Fascioloides magna. One sheep died 4 mo after inoculation and 22 immature F. magna were recovered. The second sheep remained healthy and was killed 8 mo after inoculation. Ten mature F. magna were recovered from hepatic parenchyma, and eggs of F. magna were observed in areas of the liver where flukes resided and from feces. Although F. magna is almost always lethal to sheep, this sheep was a rare definitive host.