EXPERIMENTAL HAEMONCHUS CONTORTUS INFECTION IN SHEEP: PARASITOLOGICAL EXAMINATION, HAEMATOLOGICAL ANALYSIS AND ANTHELMINTIC EFFICACY TRIAL

Abstract

Haemonchus contortus is one of the most important parasites that infects sheep and exerts its pathogenic effects by sucking blood, causing disturbances of organ-functions. The present study was conducted to examine the effect of experimental Haemonchus contortus(H.contortus)infection on haematological and parasitological parameters and to assess the efficacy of albendazole and ivermectin treatment. A total of 16sheep were allotted in to four equal groups: a single dose of 5000 third-stage (L3) infective larvae of H.contortus was orally administered to animals from the first 3 groups (Group 1- infected treated with albendazole, Group 2- infected and treated with ivermectin and Group 3 - infected non-treated) whereas the last group not infected and served as negative control. All experimentally infected animals appeared to be highly susceptible to the infection by H.contortus. All Haemonchus infected sheep showed a progressive and severe anaemia characterized by marked reductions of body weight, packed cell volume (PCV), haemoglobin concentration (Hgb) and red blood cell (RBC) count compared to control animals with a significant difference (P<0.01).Adult worm population and the egg excretion positively and significantly correlated together, whereas they were negatively associated with body weight, and the other haematological parameters. In the three groups of lambs infected with Haemonchus (G1, G2, and G3) treated with albendazole, ivermectin and non treated similar egg excretion patterns was observed starting from day 21 post infection, with a regular increase in FEC. The total mean number of H. contortus worms recovered at necropsy from abomasum of infected non-treated lambs (G3) was 1519.00.The significant loss of body weight, development of heavy worm burden and severe anaemia as indicated by reduced PCV in untreated infected lambs indicated high susceptibility of the lambs to H. contortus. On the other hand, complete absence of the parasite, improved PCV value and body weight after treatment of infected animals albendazole and ivermectin treated infected group proved 100% efficacy against H. contortus.