As many ewes and lambs watered at concrete ponds in well-drained sites acquired fluke infection as those watered at natural ponds in areas suitable for the snail intermediate hosts of Fasciola hepatica. Fasciola transmission, as evidenced by the increasing number of seropositive hosts in an enzyme-linked immunosorbent assay (ELISA), occurred during the heavy rainy period of July-September and declined with the onset of the dry season, being succeeded by the emergence of faecal positive hosts. This indicates the superiority of ELISA over coprological techniques in the early diagnosis and seroepidemiology of this parasitic infection. Host productivity, as reflected in weight gains and haematological parameters, was not significantly affected by the fluke infections.