Seasonal variation in the parasite burden and body condition of working donkeys in East Shewa and West Shewa regions of Ethiopia.

A survey of donkeys arriving at markets in three localities in East and West Shewa regions of central Ethiopia was carried out during 2002. Total faecal worm egg counts and body condition scores were measured for a total of 963 donkeys over a 12-month period. Total faecal worm egg counts did not differ significantly between localities but there was significant (p < 0.001) seasonal variation within localities. Levels of helminth infection closely followed rainfall patterns, being lowest (956 eggs per gram of faeces, e.p.g.) at the end of the long dry season (February) and highest (2022 e.p.g.) in the middle of the long wet season (August). Body condition score was associated closely with level of helminth infection (Goodman-Kruskal measure of association 0.60-0.80). Seasonal variation in body condition score reflected the temporal changes in worm burden and the availability of forage. It is suggested that a body condition score of 3 or less could be used as a simple means of identifying donkeys that require therapeutic treatment with anthelmintic. It is further proposed that economically viable strategic control of helminths in donkeys could be achieved by administering a single annual dose of avermectin-based anthelmintic at the start of the long rainy season (May-June). This may allow donkeys to recover body condition when available forage is most abundant and nutritious. It is also recommended that protein-rich feed supplementation be provided during the later part of the dry season (November-January). This may help maintain body condition when forage is scarce and the helminth challenge is at its lowest.