SEASONAL PREVALENCE OF GASTROINTESTINAL NEMATODES IN COMMUNAL LAND GOATS FROM THE HIGHVELD OF ZIMBABWE

On six occasions during a 1 year period, goats run on communal pasture s by small-scale farmers, were purchased, housed indoors for 3 weeks a nd autopsied for examination of their gastrointestinal nematode burden . All of the 32 goats examined were infected. The four dominant specie s, Haemonchus contortus, Trichostrongylus axei, Trichostrongylus colub riformis and Oesophagostomum columbianum, were present in 88-97% of th e animals. Three other nematodes, Strongyloides papillosus, Bunostomum spp. and Trichuris spp. occurred respectively in 9%, 3% and 21% of th e goats. The total nematode burden was least at the end of the dry sea son in November and increased gradually through the rainy season to re ach a peak at the end of the rains in April. The population of H. cont ortus followed the same trend as that of the total worm burden. Tricho strongylus colubriformis showed a peak in April and T axei in June. Th e fourth stage larvae (L4) of H. contortus accounted for 0-6.8% of the total H. contortus population during most of the year except in Augus t, when they comprised 46.1% of the burden. It can be concluded that t here is a direct relationship between rainfall and intensity of infect ion with gastrointestinal nematodes.