Browsing by Author "Irungu, P."
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Item Estimation of tsetse challenge and its relationship with trypanosomosis incidence in cattle kept under pastoral production systems in Kenya( 2nd May ,2008) Bett, B.; Irungu, P.; Nyamwra, S.O.; Murilla, G.; Kitala, P.; Gathuma, J.; Randolph, T.F.; McDermott, J.; Trypanosomiasis Research Centre, Kenya Agricultural Research Institute, P.O. Box 362-00902, Kikuyu, Kenya, International Livestock Research Institute, P.O. Box 30709-00100, Nairobi, Kenya, Department of Agricultural Economics, University of Nairobi, P.O. Box 29053-00625, Kangemi, Nairobi, Kenya, Department of Public Health Pharmacology and Toxicology, University of Nairobi, P.O. Box 29053-00625, Nairobi, KenyaIn an on-farm trial conducted amongst the Maasai pastoralists in Nkuruman and Nkineji areas of Kenya between April 2004 and August 2005 designed to evaluate the effectiveness of a synthetic tsetse repellent technology, we assessed the relationship between tsetse challenge and trypanosomosis incidence in cattle. Six villages were used in each area. Each of these villages had a sentinel cattle herd that was screened for trypanosomosis on monthly basis using buffy coat technique. Animals found infected at each sampling were treated with diminazene aceturate at 7 mg kg - I body weight. Treatments administered by the owners over the sampling intervals were recorded as well. Tsetse flies were trapped at the time of sampling using baited stationary traps and apparent tsetse density estimated as flies per trap per day (FrD). A fixed proportion (10%) of the flies was dissected and their infection status determined through microscopy. Blood meals were also collected from some of the flies and their sources identified using enzymelinked immunosorbent assay (ELISA). Tsetse challenge was obtained as a product of tsetse density, trypanosome prevalence and the proportion of blood meals obtained from cattle. This variable was transformed using logarithmic function and fitted as an independent factor in a Poisson model that had trypanosomosis incidence in the sentinel cattle as the outcome of interest. The mean trypanosomosis incidence in the sentinel group of cattle was 7.2 and 10.2% in Nkuruman and Nkineji, respectively. Glossina pallidipes was the most prevalent tsetse species in Nkuruman while G. swynnertoni was prevalent in Nkineji. The proportions of tsetse that had mature infections in the respective areas were 0.6 and 4.2%. Most tsetse (28%) sampled in Nkuruman had blood meals from warthogs while most of those sampled in Nkineji (30%) had blood meals from cattle. A statistically significant association between tsetse challenge and trypanosomosis incidence was obtained only in Nkuruman when data was pooled and analyzed at the area but not at the village-level. In the later scenario, lagging tsetse challenge by I month improved the strength but not the significance of the association. These findings show that when the spatial unit of analysis in observational studies or on-farm trials is small, for instance a village, it may not be possible to demonstrate a statistically significant association between tsetse challenge and trypanosomosis incidence in livestock so as to effectively control for tsetse challenge.Item Financial Implications of Rearing Sheep and Goats under Natural Trypanosomosis Challenge at Galana Ranch, Kenya(2002) Irungu, P.; Nyamwaro, S.O.; Masiga, D.K.; Kenya Trypanosomiasis Research Institute; Kenya Trypanosomiasis Research Institute, PO Box 362, Kikuyu, KenyaA study to compare the profitability of rearing sheep and goats under natural trypanosomosis challenge was carried out on Galana ranch m south-eastern Kenya between July 1996 and October 1997. Seventy-nine male weaner sheep and 79 male weaner goats were monitored monthly for weight changes and fortnightly for trypanosomosis. The animals of each species were divided into two groups Group I was an untreated control, while group 2 was treated with Isometamidium chloride (Samonn) at 0.5 mg/ kg body weight every 3 months In both groups, trypanosome infections were detected by microscopy and treated With diminazene aceturate (Venben), at 3.5 mg/kg body weight, when the packed cell volume reached 17";', or below The profitability of each drug regime was expressed as the marginal revenue over the cost of trypanosomosis (MOT) There were greater losses occasioned by trypanosomosls m sheep than m goats. Animals of both species on chemoprophylaxis gave higher MOT values than those that received chemotherapy on diagnosis However, the MOT values for the chemoprophy-lactic regime were higher for sheep than for goats, suggesting that the greater weight gam by sheep more than compensated for the higher cost of maintaining them under high trypanosomosls challenge Thus, a Galana rancher would be better off keeping sheep rather than goats, other things being equal. The marginal revenue per dose of Samonn was lower than that of Venben for both species, suggesting that strategic use of Samorin timed to precede the peak incidence of trypanosomosls might be a better option to raise the overall profitability in sheep and goatsItem Growth and Mortality in Sheep and Goats under High Tsetse(2002) Masiga, D.K. ; Okech, G.; Irungu, P. ; Ouma, J; Wekesa, S. ; Ouma, B.; Guya, S.O.; Ngung'u, J.M.; Kenya Trypanosomiasis Research Institute; Kenya Tryponosomiasis Research Institute; Kenya Trypanosomiasis Research Institute (KETRI), PO Box 362, Kikuyu, KenyaTrypanosomosis is a major Impediment to livestock production and economic development In those areas of Africa where It IS endemic Although small ruminants appear to perform better than cattle In various agro ecological zones, the Importance of trypanosomosis has not been extensively Investigated m these livestock This study was designed to Investigate the prevalence of trypanosomosis In sheep and goats In an endemic area and to evaluate the performance of different breeds under high tsetse challenge and the potential role of chemoprophylaxis In the control of the disease The results showed that tsetse flies reed readily on small ruminants, and that these al1lmals are susceptible to trypanosomosls The Small East African goats acqll1red fewer Infections than the Black Head Persian and Dorper sheep used In the study. In both sheep and goats, chemoprophylaxis With Isometanidium chloride (Samonn, Rhone Meneux, and Annecy, France) was protective, resulting in fewer infections and higher body weight gain. Trypanosomosls caused anaemia in both sheep and goats, and animals whose PCV fell below IS'X, rarely recovered, even with trypanocidal drug treatment. The peak transmission period was between 1 and 3 months after the peak tsetse fly density, which raises the possibility of effective strategic prophylaxis.
