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Studies on Schistosoma bovis in Ethiopia
Abstract:
Schistosoma bovis occurs in at least seven of the 14 rovinces of Ethiopia. Results of faecal and snail surveys in three foci are reported. Adwa. One collection showed that nine out of 26 bulinids were infected with S. bovis. The snail host was a tetraploid form of Bulinus (n = 36). The examination of 200 specimens of cattle faces revealed no S. bovis eggs, which was attributed to poor technique or light infection. Gewani. The snail host was Bulinus abyssinicus, which was also infected with S. haematobium, the combined infection rate being 60%. S. bovis eggs were seen in 1-5% (3/197) of specimens of cattle faeces. Lake Awassa. Among 715 bulinids(a mixture of diploid (n = 18) and tetraploid (n = 36) forms), 22 were infected with S. bovis. Infected snails all belonged to the tetraploid form. Infection in cattle faeces was 5-5%(11/200). The Fasciola infection rates in these three areas were 29%, 78% and 60% respectively. Susceptibility of laboratory and wild animals to the Gewani and Lake Awassa strains of S. bovis was investigated. Combined results show that there are at least five species of wild rodents in Ethiopia which are susceptible to S. bovis: Arvicanthis niloticus, Praomys albipes, Rattus rattus, Mastomys coucha and Lophuromys flavopunctatus, in addition to hamsters, white mice, rabbits and guinea pigs. Immature female worms resembling S. bovis were recovered from a goat and a sheep exposed to a mixture of S. bovis and S. haematobium cercariae shed by naturally infected snails. Using the same mixture of cercariae, a Gelada baboon (Theropithecus gelada) could be infected by both schistosomes, but a dog was completely refractory. ABSCESS. Some of these inconclusive results are thought to be due to a unisexual infection. The Gewani strain of SEWANI STRAIN OF S. bovis had a wider range of snail hosts than the Adwa and Awassa strains, covering the tropicus, truncatus and africanus groups of Bulinus. The Adwa and Awassa strains could infect only members of the truncatus group.