Serological responses of cattle after treatment and during natural re-infection with Fasciola hepatica, as measured with a dot-ELISA system

The dot-ELISA reaction was used to study the dynamics of IgG titers in catt le naturally infected with Fasciola hepatica after anthelmintic treatment a nd during reinfection. Excretion/secretion products (ES) of the parasite we re used as antigens for the dot-ELISA. IgG antibodies were no longer detect able by dot-ELISA, 4-6 months after nine animals received the first of thre e weekly doses of triclabendazole (15 mg kg(-1)) and were then maintained o n a pasture free of F. hepatica metacercariae. Six fluke-free cattle began shedding F. hepatica eggs 3-6 months after grazing a pasture contaminated w ith metacercariae of the parasite. A detectable increase in dot-ELISA IgG a ntibody levels was observed 2-4 weeks after natural reinfection by grazing a similar pasture contaminated with F: hepatica metacercariae. The usefulne ss of the dot-ELISA system to diagnose chronic infection by serology is com plicated by previous treatment against the parasite. It is concluded that t he ES antigens can be useful to detect early infection of cattle with F: he patica in a dot-ELISA system (C) 2000 Elsevier Science B.V. All rights rese rved.