In the case of F. hepatica, there is convincing data that infection with this trematode results in altered anti-bacterial immune responses in ruminants: F. hepatica infection in cattle confers susceptibility to Salmonella dublin as a consequence of parasite-induced suppression of Th1-type immunity [2], whereas peripheral blood mononuclear cells (PBMC) from cattle experimentally coinfected with Mycobacterium bovis and F. hepatica secrete reduced levels of IFN-γ in response to stimulation with mycobacterial antigens compared to PBMC from animals infected with M. bovis alone [29]. This evidence concerns the gene IFNG and infection.