Strongylus vulgaris in donkeys (Equus asinus) from the highveld of Zimbabwe.

Strongylus vulgaris populations in the cranial mesenteric arteries, caecum and colon were studied in 14 donkeys obtained from a communal area of the Zimbabwean highveld during July and November, 1986, and January and April 1987. Adult parasites were present in all animals and larvae in the cranial mesenteric arteries of 12 animals. Aged animals had high worm burdens. The number of adult parasites varied from 63 to 1255 (mean 382) and of larvae in the arteries from 0 to 181 (mean 69). The mean adult worm burdens were highest in July (400) and November (488), and lowest in April (107). The mean arterial larval burden was highest in July (130) and lowest in November (21). These observations indicate that infection with S. vulgaris takes place during the rainy season resulting in the heavy arterial larval population from January onwards and the heavy adult population during the dry season.