The transmission of Leishmania infantum chagasi by the bite of the Lutzomyia longipalpis to two different vertebrates

This study presents the establishment of a transmission model of Leishmania infantum chagasi by the bite of Lutzomyia longipalpis, the vector of American visceral leishmaniasis. The parasites were successfully transmitted by infected sandfly bites to mice and hamsters, indicating that both animals are good experimental models. The L. infantum chagasi dose that was transmitted in each single bite ranged from 10 to 10, 000 parasites, but 75% of the sandflies transmitted less than 300 parasites.The strategy for initiating infection by sandfly bite of experimental animals facilitates future investigations into the complex and dynamic mechanisms of visceral leishmaniasis. It is important to elucidate the transmission mechanism of vector bites. This model represents a useful tool to study L. infantum chagasi infection transmitted by the vector.Despite the fact that Leishmania is transmitted exclusively by sandfly vectors, a reproducible animal model of Leishmania infection transmitted by sandfly bite was only described in the year 2000 [1].Early investigations showed that infected P. papatasi sandflies can release from 0 to over 1,000 L. major promastigotes through their proboscides by forced feeding [2]. However, a transmission model by bite with P. duboscqui infected with L. major found that the parasite numbers inoculated in the host skin by one insect vector alone could vary from 10 to 100,000 [3].Considering the New World species of Leishmania, using a feeding device of chick skin membrane over culture medium showed that L. longipalpis sandflies infected with Leishmania mexicana (an unnatural vector/parasite pair) expelled an average of 1,000 parasites per fly [4]. Thus, even though L. longipalpis is the vector of L. infantum chagasi in nature, it is permissive in the laboratory to infection with other Leishmania species.In consideration of the continuing prevalence of American visceral leishmaniasis and the paucity of related studies in the literature, our goal was