Rodent infection with Leishmania in a new focus of human cutaneous leishmaniasis, in northern Iran.

The incidence of zoonotic cutaneous leishmaniasis (ZCL), which is endemic in several parts of Iran, has recently increased in the rural areas of the northern district of Damghan, in Semnan province. Between 2001 and 2004, as part of an investigation of this worrying trend, wild rodents in this region were caught and checked, by the microscopical examination of liver and spleen smears, for leishmanial infection, to see which species were acting as 'reservoir' hosts. Overall 298 Nesokia indica, 29 Meriones libycus, 10 Mus musculus and two Microtus socialis were caught. Most of the N. indica (61%) and Me. libycus (52%) but none of the other rodents were found smear-positive for leishmanial amastigotes. When PCR was used to test scrapings from 50 of the smears (of which 25 had been found to harbour amastigotes, by microscopy), 29 (58%) of the smears were found positive for the kinetoplast DNA of Leishmania major; none was found positive for any other Leishmania species. Nesokia indica and Me. libycus are therefore incriminated as the main 'reservoir' hosts of L. major in Damghan.