Evaluation of the fat-tailed gerbil, Pachyuromys duprasi (Rodentia: Gerbillidae), as a new animal model for studies of Leishmania major infection and transmission.

Abstract

The fat-tailed gerbil Pachyuromys duprasi is a common burrowing rodent found across the northern Sahara Desert from Morocco to Egypt. There is overlap in the geographical distribution and ecological habitats of P. duprasi, several Old World Leishmania species, and numerous sand fly vectors of Leishmania, but there are no records that document the natural occurrence of this gerbil with any species of Leishmania or phlebotomine sand fly. Experiments were conducted to determine its potential as a natural host and laboratory animal model for Leishmania major. Captive-born P. duprasi were inoculated subcutaneously (s.c.) in the tail with promastigotes or amastigotes of an Egyptian strain of L. major and monitored for signs of infection. Local swelling and erythema was visible 10-12 days after amastigote inoculation, and within 3-4 weeks swelling had increased tail widths by up to 78%. Infections progressed more slowly and less conspicuously following inoculation with promastigotes. Tissue density of amastigotes in the gerbil's tail lesions after inoculating with either stage of L. major was significantly lower than that produced in the footpads of BALB/c mice by the same parasite and incubation period. Laboratory transmission of L. major to P. duprasi by sand fly bite was demonstrated and acquisition of L. major, by bite, from tail lesions of infected P. duprasi to laboratory-reared Phlebotomus papatasi was also achieved with 10% of biting flies developing promastigote infections. The acquisition and development of L. major infections in P. papatasi after biting an infected P. duprasi and the susceptibility of P. duprasi to L. major delivered at low densities by sand fly bites indicate that fat-tailed gerbils could serve as a natural host and reservoir of L. major.