Comparative infectivity of a Kenyan strain of Leishmania donovani amastigotes for Rattus rattus and the laboratory white rat.

Amastigotes of a Kenyan strain of Leishmania donovani from a previously infected hamster were used to inoculate Rattus rattus and the laboratory white rat intracardially. The animals were sampled at 2, 4, 6, and 12 weeks post-inoculation to determine infectivity and total parasite burdens in the liver and spleen. Higher parasite burdens were observed in the livers and spleens of R. rattus. Parasite culture indicated more generalized parasite dissemination compared to the white rat. Demonstration of the parasite in dermal tissue of R. rattus at 2 and 4 weeks suggests that the parasite may be accessible to sandfly vectors. Transient susceptibility to systemic infection and parasite survival in dermal tissue suggests a potential role of R. rattus in the transmission cycle of Kenyan visceral leishmaniasis.