I.A. Shambwana
Department of Livestock Development
P.O. Box 159
Zanzibar, Tanzania
East Coast fever (ECF) caused by Theileria parva continues to be a major killer of cattle in nearly all parts of Unguja Island, Zanzibar, where the disease is enzootic. According to Irvin (1984), ECF has its greatest impact on calves on smallholder farms. On government farms that practice strict tick control, the disease is more commonly seen in adult cattle as a result of occasional breakdowns in acaricidal protection. However, in many field outbreaks both calves and adults seem to be equally susceptible. Pure or exotic breeds and their crosses are more susceptible to the disease, and have a higher mortality rate (6.0% and 18.3%, respectively), than local Zebu cattle.
In a serological survey carried out by Flach (1988) using the indirect fluorescent antibody test, positive animals were detected in all areas sampled, which represented every district of the island (Figure 1).
Many outbreaks of ECF in the rural areas are not reported. Livestock owners may attempt to treat their afflicted animals in traditional ways, such as by burning the swollen lymph nodes of the animals with a hot iron, or they may slaughter the animals. Of reported cases of ECF, the records of the Department of Livestock Development show the yearly average number of cases to be nearly 800.
The numbers of exotic and cross-bred cattle have increased markedly in the past eight years due to a successful artificial insemination programme. Many farmers are becoming disillusioned, however, because of the high mortality in these animals that appears, from descriptions of the disease, to be caused mainly by ECF. In recent years, treatment with parvaquone (Clexon, Wellcome) has been introduced. This drug is effective if treatment is started early, but it is extremely expensive and many farmers cannot afford to have their animals treated. A new approach to ECF control has been explored over the last two years using tick stabilate infection and tetracycline treatment to immunize cattle against T. parva. Results of these trials using this infection and treatment were promising. The Department of Livestock Development will continue to explore the potential of this control measure and if satisfied with the protection will start field immunization of cattle.
Figure 1. The percentage of animals less than one year old with antibodies to Theileria parva in different districts of Unguja Island, Zanzibar.
REFERENCES
Flach, E.J. (1988). One-year study on East Coast fever on Unguja, Zanzibar. Unpublished report for the Overseas Development Administration. Zanzibar Government.
Irvin, A.D. (1984). Report on a mission to evaluate East Coast fever in Zanzibar (December 1984). Nairobi: The International Laboratory for Research on Animal Diseases.
