Comparative parasitological and haematological changes in two breeds of sheep infected with Fasciola gigantica

Twelve each of Red Masai and Dorper sheep, aged between 6 and 9 months, wer e acquired from a Fasciola-free area of eastern Kenya. Each breed was divid ed into two groups of 6. The sheep in one group of each breed were experime ntally infected with 400 viable metacercariae of Fasciola gigantica. The ot her group of 6 sheep of each breed remained as uninfected controls. The ani mals were monitored regularly for any evidence of disease. Blood samples ta ken weekly revealed a general reduction in red cell counts and packed cell volume, which was much faster in the infected Dorper sheep than in the Red Masai. This reduction started from the tenth week after infection and persi sted to the end of the experiment 18 weeks post infection (PI). The absolut e eosinophil counts rose in all the infected animals, but the values were h igher among the Dorper than among the Red Masai. Patency occurred at weeks 12 and 13 PI in the Red Masai and Dorpers, respectively, with the latter sh edding significantly more fluke eggs. The worm recovery rates were higher a mong the Dorpers than among the Red Masai, though not significantly so. On the basis of egg counts and clinicopathology, the Dorper sheep were conside red to be more susceptible to F. gigantica infections.