ABSTRACT

The prevalence of tsetse flies and ruminant trypanosomiasis in five selected Local Government Areas of Abia State, Nigeria and some pathophysiological aspects of the disease were investigated in ruminants and in experimental rat model. Tsetse fly populations were sampled for one year, from April 2003 to March 2004 using bioconical traps. A total of 613 tsetse flies were captured and the population structure, physiological status, prevalence of the species in the area and infection rates were elucidated. The survey found Glossina palpalis as the predominant tsetse species in the area. There were significantly more (P<0.05) females than males in the species found. Higher tsetse density (P<0.001) was encountered during the rainy season than in the dry season and among the areas sampled, Isuikwuato LGA recorded the highest number (X 2 =563.2, df = 4, P<0.001) of flies caught. The tsetse population had higher proportion of hungry flies. Four hundred and twenty seven flies were dissected and examined microscopically for the presence of trypanosome infection, 3.9% of which were infected with trypanosome. Trypanosome prevalence in cattle, goats and sheep were studied in the same localities where tsetse flies were sampled and at the same period. A total of 1361 animals were examined and the overall prevalence of trypanosomiasis was 1.9%. The prevalence in the different ruminant species was 3.7% in cattle, 1.2% in goats and 1.1% in sheep. Infection was lower (P<0.05) in animals resident in the State than those from semi-nomadic and slaughter houses. The overall gender and age related infection were not obvious. Among the positive animals, 11 (42.3%) and 15 (57.7%) were due to T. congolense and T. vivax respectively. T, vivax was the leading species encountered in cattle while T. congolense was more predominant in small ruminants. The result shows that the number of animals infected is significantly (P<0.001) dependent on the time of the year, location sampled (X = 18.47, df = 4, P<0.001) and animal species (X = 7.89, df= 2, P<0.05). The effect of Trypanosome infection in ruminant animals as well as in rat model showed that infected animals had significantly lower (P<0.05) packed cell volume, erythrocyte xiii count and higher (P<0.01) mean cell volumes than uninfected animals. Leucocytosis, reticulocytosis and thrombocytopenia were also observed. The infection also produced a decrease in albumin (P<0.001), significant increase in total protein and bilirubin levels. These changes were not seen in the animals that were not infected. Rat infection further revealed development of parasitaemia within 7 days of intraperitonial inoculation and irregular fluctuations of parasitaemic levels with maximum parasitaemia attained on day 16 post infection. There was also growth retardation, defect in coagulation, electrolyte and aspartate enzyme levels and in histology of kidney and liver as compared with uninfected control rats. On the other hand trypanosome infection has no effect on osmotic fragility of the red cells and such minerals as Cu. Mn and Mg but with reduction in Zn and Fe. These results establish that tsetse flies and ruminant trypanosomiasis are present in Ahia State at low prevalence suggesting that Ahia is suitable for livestock production. The disease also produced adverse patbophysiological changes in the host that validate trypanosomiasis as a devastating disease constraining livestock production in subSahara Africa