F.C. Munatswa
Veterinary Research Laboratory
P.O. Box 8101
Causeway, Zimbabwe
Tick-borne diseases are a major cause of cattle losses in Zimbabwe. The diseases of importance are babesiosis, anaplasmosis, heartwater and theileriosis. East Coast fever (ECF), caused by Theileria parva parva, was introduced into the country at the turn of the century by cattle from East Africa. The disease caused heavy losses initially but was eventually eradicated in 1954 by intensive dipping. Two subspecies, however, remained: T. p. bovis, causing January disease, and T. p. lawrencei, causing Corridor disease. These two diseases are responsible for about 2000 cattle deaths each year. Outbreaks of T. p. bovis occur only in highveld areas infested with the brown ear-tick, Rhipicephalus appendiculatus. Outbreaks of T. p. lawrencei are associated with the presence of buffalo and occur most commonly in the southern lowveld where the main vector is the lowveld brown ear-tick, R. zambeziensis.
In a serological survey, Norval et al. (1985) found that antibodies to the T. parva group of parasites occurred in cattle throughout the country but the percentage of reactors was generally low. Outbreaks of T. p. bovis were largely restricted to the commercial farming areas, where R. appendiculatus was most abundant. The tick was not common in over-grazed communal farming areas. Clinical cases of T. p. bovis were not recorded from areas infested with R. zambeziensis.
Outbreaks of T. p. bovis in Zimbabwe follow a seasonal pattern and occur most commonly between January and March; this coincides with the activity period of the adult stage of R. appendiculatus.
REFERENCE
Norval, R.A.I., Fivaz, B.N., Lawrence, J.A. and Brown, A.F. (1985). Epidemiology of tick-borne diseases of cattle in Zimbabwe. 3. The Theileria parva group. Tropical Animal Health and Production 17:19-28.
