| dc.description.abstract | Twel ve Red Masai Sheep and twelve Dorper sheep aged
between six and nine months were acquired from a fluke free
area. Animals of each breed were divided into two groups of
six animals each. six of the animals in each breed were
experimentally infected with 400 viable metacercariae of
Fasciola gigantlca each, with the aim of comparing the
susceptibility of the two breeds to the parasite. The other
six sheep of each breed acted as uninfected controls. The
animals were monitored regularly for any evidence of clinical
disease and their body weights measured. Blood samples were
also taken from each sheep at weekly intervals and used to
determine the packed cell volume, haemoglobin concentration,
red blood cell counts, erythrocyte indices, total and
differential leucocyte counts, and serum levels of total
proteins, albumin, bilirubin, and gamma glutamate transferase
and for plasma fibrinogen levels. In addition faecal samples
were screened on a weekly basis for fluke egg counts.
Postmortem was conducted at the ninth ~nd eighteenth weeks of
the experiment or on death of the animals to study the
pathology and recover and count the flukes.
Red blood cell counts and packed cell volumes generally
dropped faster an the infected Dorper sheep than in the
infected Red Masai sheep starting from the tenth week to the
end of the experiment (P< 0.05) The absolute eosinophil
counts rose to a much higher level in the infected Dorper
sheep than in the infected Red Masai sheep (P < 0.05).
1
Bilirubin and GGT were elevated to significantly higher
levels in the infected Dorper sheep than in the infected Red
Masai sheep (P < 0.05), while fibrinogen was elevated much
earlier in the infected Red Masai sheep than in the infected
Dorper sheep.
The Dorper sheep shed significantly more fluke eggs than
the Red Masai sheep and the mean fluke counts after recovery
from the livers ~ere 23.5 for the Red Masai and 41.77 for the
Dorper sheep.
The gross pathological findings in all the animals
included excessiv~ amounts of blood tinted fluid in the body
cavities and severely damaged livers. The lesions in the
livers were generally more numerous in the Dorper sheep than
in the Red Masai sheep. Microscopically, foci of haemorrhages,
.hepatocyte degeneration, leucocytic infiltrations, and
proliferation of the small bile ducts were evident. In
addition, the animals sacrificed at 18 weeks post-infection
revealed adhesions of the liver to the viscera and toughening
of the livers, which were difficult to cut with a knife.
Histologically, these livers were fibrotic and this was more
marked in the Dorper sheep than in the Red Masai sheep.
On the basis of these clinicopathological criteria and
fluke egg counts, Dorper sheep were found to be more
susceptible to experimental F. gigantica infection than Red
Masai sheep. | en |
