Epidemiology and control of ruminant helminths in the Kericho Highlands of Kenya
The studies reported in this thesis have been conducted in a high potential area of the country where no previous studies had been undertaken. The two major components of the research were an epidemiology study and an intervention study, both of which were conducted on farms in the peri-urban area of Kericho. An initial background study was conducted to collect data from the local Veterinary Investigation Laboratory, from extension staff in a participatory rapid appraisal (PRA) study and a cross-sectional socio-economic survey was undertaken with local farmers. These provided some understanding of the problems caused by helminths and the approaches taken to control them, together with socioeconomic data relating to the keeping of livestock in the area. Disease appeared to be a major constraint affecting ruminant productivity, with nematodoses appearing to be the most important helminth disease in the area particularly in small ruminants. In the cross-sectional survey, more than 60 % of farmers reported that they administered anthelmintics therapeutically and over 30 % gave routine treatments. On average, cattle were reported as being given up to 1.5 treatments per year, sheep just over 1.1 and goats 0.9 treatments per annum. In general, extension workers recommend that animals are wormed every 3 - 4 months, however this practice was not adopted by the farmers because of the expense involved. The epidemiology study conducted on 27 smallholder farms over a 22 month period obtained data on the prevalence of a) helminth ova in cattle, goat and sheep faeces b) helminth larvae on herbage and c) the different nematode species acquired by introduced Dorper tracer lambs which grazed on communal land. Grazing ruminants in Kericho appear to be exposed to infection with gastrointestinal nematodes throughout the year, there was no evidence of a marked seasonal influence on the availability of infective larvae on pasture. The two commonest genera Trichostrongylus and Haemonchus are both well adapted to the three ruminant species that are commonly grazed together.