REDUCED EGG COUNTS IN MIXED INFECTIOUS WITH ESTRUS-OVIS AND HAEMONCHUS-CONTORTUS - INFLUENCE OF EOSINOPHILS

In all, 2 groups of lambs were infected either with Oestrus ovis first -instar larvae or with 10,000 third-stage larvae (L3) of Haemonchus co ntortus. Another group of lambs was infected with both parasites. Feca l nematode egg counts, plasma pepsinogen concentrations, specific O. o vis enzyme-linked immunosorbent assay (ELISA) antibodies, and blood eo sinophil counts were monitored and compared to with the values recorde d for a control group of uninfected lambs. There was no significant di fference between the burden of H. contortus found in mixed and single infections. However, the nematode egg production was significantly dep ressed in mixed infections. O. ovis affects the population of H. conto rtus at least by decreasing the parasite egg output. This effect may b e mediated through the increase in eosinophil production stimulated by the presence of O. ovis.