A cross-sectional coprological survey in the regions of Ada, Akaki, Bereh and Boset, and a retrospective postmortem investigation were conducted to study the epidemiology of Parascaris equorum in donkeys and horses in Ethiopia. Faecal samples from 803 working donkeys and 402 horses were collected, and the numbers of worms recovered from 112 donkeys examined postmortem between 1995 and 2004 were analysed. There was a high prevalence of infection and faecal egg output of P equorum in both donkeys and horses, and the severity of the infection in donkeys was increased irrespective of their age. The prevalence of the infection in the donkeys was 51·1 per cent and in the horses 16·2 per cent, and the prevalence in the donkeys examined postmortem was 55 per cent. There was no significant difference between different age groups of donkeys in either the prevalence or the intensity of the infection. The prevalence of the infection was significantly higher in the Ada and Akaki regions than in the Bereh and Boset regions.
Parascaris equorum is an important parasite of young horses, particularly sucklings and weanlings (Russell 1948, Soulsby 1982, Austin and others 1990, Southwood and others 1998). The parasite has a worldwide distribution, and is usually present wherever horses are raised (Clayton 1986, Southwood and others 1998). It can reduce the growth rate of foals and cause occasional deaths due to intestinal obstruction or rupture (Dipietro and others 1983, Clayton 1986, Ryu and others 2004).
P equorum has also been reported in donkeys from various regions of the world (Tolliver and others 1985, Vercruysse and others 1986, Pandey and Eysker 1990, Ricci and Sabatini 1992, Burgu and others 1995, Daoud and Al-Alousi 1995, Feseha 1998, Lewa and others 1998, Getachew 1999, Kotwal and others 2000, Matthee and others 2002). However, most of these reports concern only small numbers of animals, and the information is rather fragmentary. There have been no specific studies of the epidemiology, pathogenicity and immunology of parascarid infections in horses and donkeys under the tropical weather conditions of Ethiopia. The aim of the present study was to investigate the epidemiology of this parasite in working donkeys and horses in Ethiopia by means of a cross-sectional coprological survey and retrospective postmortem examination findings.