Susceptibility of Some Wild Rodents Widely Distributed in Egyptian Foci to Schistosoma mansoni Infection under Laboratory Conditions

The most important definitive host of Schistosoma mansoni is the human, however, numerous other mammalian species were found to be infected with this parasite. Among these species, the wild rodents are the most common. In this study, the susceptibility of some wild rodents widely distributed in Egypt to S. mansoni infection was evaluated. Five wild species were tested for the susceptibility of S. mansoni infection in vitro; including Mus musculus (black mice), Acomys cahirinus (Cairo spiny mice), Rattus rattus (house rats), Rattus norvegilcus (Norway rats), Rattus norvegicus (albino rats) and Arvicanthis niloticus (Nile rats). Laboratory mice were used as a positive control. Rodents were infected individually with 150 S. mansoni cercariae by tail immersion and housed for 8 week post-infection. The results reported that the Nile rats showed the highest number of worm burden (90 worms), while the Norway rats and the laboratory rats showed the lowest numbers among the tested species. This study also showed that the Nile rats, the house rats and the Norway rats yielded high number of eggs in the liver tissues. In contrast, the Cairo spiny mice, the black mice and albino rats yielded low number of eggs in the liver tissue. As compared to the permissive host albino mice, the Nile rats, the black mice, the Cairo spiny mice and the house rats showed comparable granuloma size. In contrast, albino rats and Norway rats showed a small granuloma size. Alltogether, these data showed that S. mansoni infection to these wild rodents was species dependant.