Abstract. Participatory research on bovine trypanosomiasis was conducted with Orma pastoralists in Tana River District, Kenya. The use of participatory methods to understand local perceptions of disease signs, disease causes, disease incidence by cattle age group, seasonal patterns of disease and preferences for indigenous and modern control methods are described. Results indicated that local characterization of diseases called gandi and buku by Orma pastoralists was similar to modern veterinary knowledge on chronic trypanosomiasis and haemorrhagic trypanosomiasis (due to Trypanosoma vivax), respectively. The mean incidence of gandi varied from 10.2% in calves to 28.6% in adult cattle. The mean incidence of buku varied from 3.1% in calves to 9.6% in adults. Pearson correlation coefficients for disease incidence by age group were 0.498 (P < 0.01) and 0.396 (P < 0.05) for gandi and buku, respectively. Informants observed cases of trypanosomiasis in 24.1% of cattle (all age groups); these cases accounted for 41.8% of all sick cattle during the preceding 12-month period. Eight indigenous and three modern trypanosomiasis control methods were identified. Results indicated that an integrated approach to trypanosomiasis control based on private, individual action was well established in the assessment area. When presented with four different trypanosomiasis control methods, community representatives selected`better use of trypanocides' as the most preferred intervention and`community-based tsetse control' as the least preferred intervention. This finding prompted researchers to modify the original project activities. Constraints facing the sustainability of community-based tsetse control are discussed.

Cattle are the major source of food security and income for pastoral farmers in sub-Saharan Africa. However, infectious and parasitic diseases remain a major constraint to improved cattle productivity in the region. The use of animal health economics to support decision-making on cost-effective disease control options is increasingly becoming important in the developing world. Trypano-tolerant indigenous Orma / zebu cattle in a trypanosomosis-endemic area of Kenya were evaluated for economic performance using gross-margin analysis and partial-farm budgeting. Orma / zebu and Sahiwal / zebu cross-bred cattle were exposed to similar husbandry practices and monitored for growth rate, incidence of common infections (trypanosomosis, anaplasmosis, babesiosis, East Coast Fever and helminthosis) and the cost of treatment assessed. Interview questionnaires were also used to assess the preference rating of the 2 breeds. Results indicated that incidence of infection was trypanosomosis 3 %, anaplasmosis 58 %, babesiosis 11 %, East Coast Fever 22 % and helminthosis 28 %, with no significant difference between breeds. The Orma / zebu and Sahiwal / zebu breeds had comparable economic benefits, hence a pastoralist in Magadi division is likely to get similar returns from both breeds. This study therefore recommends adoption of not only the Sahiwal / zebu but also the Orma / zebu breed for cattle improvement in trypanosomosis endemic areas and conservation of indigenous genetic resources

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A study to compare the profitability of rearing sheep and goats under natural trypanosomosis challenge was carried out on Galana ranch in 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 1 was an untreated control, while group 2 was treated with isometamidium chloride (Samorin) at 0.5 mg/kg body weight every 3 months. In both groups, trypanosome infections were detected by microscopy and treated with diminazene aceturate (Veriben), 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 trypanosomosis in sheep than in goats. Animals of both species on chemoprophylaxis gave higher MOT values than those that received chemotherapy on diagnosis. However, the MOT values for the chemoprophylactic regime were higher for sheep than for goats, suggesting that the greater weight gain by sheep more then compensated for the higher cost of maintaining them under high trypanosomosis challenge. Thus, a Galana rancher would be better off keeping sheep rather than goats, other things being equal. The marginal revenue per dose of Samorin was lower than that of Veriben for both species, suggesting that strategic use of Samorin timed to precede the peak incidence of trypanosomosis might be a better option to raise the overall profitability in sheep and goats.

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