Dynamics of Leishmania infection rates in Rhombomys opimus (Rodentia: Gerbillinae) population of an endemic focus of zoonotic cutaneous leishmaniasis in Iran.

Zoonotic cutaneous leishmaniasis (ZCL) due to Leishmania major is a great public health problem in the Old World. Leishmania major is widely distributed in populations of rodents in arid and savannah regions. In this study, seasonal variation of natural infection with Leishmania parasites in Rhombomys opimus (Rodentia: Gerbillinae) population of an endemic focus of ZCL in Iran was monitored. The study was conducted from October 2007 to October 2008 in the central part of the country. Nested polymerase chain reaction (PCR) assay was used for the detection and identification of Leishmania parasites, and the results were confirmed by PCR-restriction fragment length polymorphism (RFLP). The results showed that Leishmania infection rate was 55.8% (29 out of 52 gerbils) using nested PCR. The highest and lowest Leishmania infection rates were observed in fall and summer, respectively. Gerbils that were found to be infected only with L. major were 5.8%, and that with Leishmania turanica were 23.1%. A mixed natural infection was seen in the rodents with L. major and L. turanica (21.2%), with L. major and L. gerbilli (1.9%), and with all the three species (3.9%). Leishmania major infection alone was seen in fall and winter whereas mixed infection of L. major and L. turanica was observed in all seasons except in summer. Leishmania turanica infection was observed throughout the year. It is concluded that L. major, L. gerbilli, and L. turanica circulate in the population of R. opimus in central part of Iran. Leishmania major infection is usually accompanied by L. turanica in naturally infected gerbils with the highest rate in fall. It is recommended that the role of L. turanica in the epidemiology and transmission of ZCL should be reconsidered.