Ecoepidemiology of leishmaniases in Syria. 3. Leishmania major infection in Psammomys obesus provides clues to life history of the rodent and possible control measures.

Collections of Psammomys obesus from near Damascus, Syria in May 1990 and November 1991 contained animals of all ages. Both series had a high prevalence of Leishmania major infection. Lesions were small in November and large in May. Assuming the two collections were representative of typical years, it is inferred that the breeding season is between October and May: there is high winter mortality of animals born early in the breeding season, but high survival of their parents, and there is high mortality in summer of animals aged between 17 and around 20 months. Transmission in summer is, therefore, between old adults shortly before their death and young adults born in late winter or spring. Juvenile animals are not exposed to the infection. If these findings are confirmed it should be relatively easy to break this tenuous cycle.