STUDIES ON THE INTERACTIONS BETWEEN OESTRUS OVIS (L1) AND HAEMONCHUS CONTORTUS (L3) IN EXPERIMENTALLY INFECTED GOATS
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2008-06
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Abstract
Concurrent parasitic infection of animals is a common phenomenon in the field. The existence of one species may often positively or negatively influences the biology and development of the other. The results of previous experimental studies on sheep model under temperate conditions have shown that infection with Oestrus ovis adversely affected populations of either Haemonchus contortus or Trichostrongylus colubriformis. However, under tropical condition no information was available on the interactions between the parasites located in remote anatomical site mainly using goat model. Hence, an experimental study was conducted with the objective to determine the possible occurrences of interactions between O. ovis and H. contortus using specifically Ethiopian local Afar breed of goats. A total of twenty goats were allocated into four groups (O, OH, H, and C) of five animals. Groups O and OH animals, each received a total of 56 first instar larvae (L1) of O. ovis in five consecutive infections between days 0 and 35, and then on day 42 animals from groups OH and H were infected with a single dose of 5000 third stage larvae (L3) of H. contortus. Goats from group C were kept free of any infection as non-infected controls. Faecal egg counts (FEC), blood cell counts, total serum protein levels and body weight changes were measured weekly throughout the study period. All experimental animals were humanly killed on day 98. At necropsy worm burden, female worm length and fecundity as well as O. ovis larval burdens in the nasal-sinus cavities of infected animals were assessed. The results showed that the presence of H. contortus in the abomasum of group OH had no any influence on the development of O. ovis in the nasal-sinus cavities. In contrast, infections with O. ovis before H. contortus was related with significant reduction (P<0.05) in FEC, worm burdens, fecundity and female worm length in group OH compared with mono-infected animals (group H). This was associated with in higher blood eosinophilia and packed cell volumes (PCV) which was significantly different (P<0.05) from O. ovis mono-infected animals.
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Concurrent infection, Oestrus ovis, Haemonchus contortus, Interaction