A new study published in Science finds for the first time evidence of sexual reproduction in the protozoan parasites in the genus Leishmania, causing skin ulcers and potentially fatal disease, Leishmaniasis. The American scientists show that mating and subsequent genetic exchange occurs when the parasites are in the sand flies.

Leishmaniasis is a problem in most of the development world. The disease are caused by parasitic protozoan, who are transmitted to humans and other mammals by the bites of sand flies. Several different species of Leischmania exist including some that stay in the skin and cause sores and ulcers at the bite site, which usually disappears after half a year leaving behind scars and others that migrate to the organs and cause potentially fatal damage to these. Luckily, leishmaniasis can be treated with various drugs. However, some species have acquired resistance to some of the drugs and more knowledge on the life cycle and biology of these parasites are needed to develop more effective treatments.


By conducting molecular studies on the DNA in different groups of parasites from the various stage that Leischmania goes through during its development, the scientists could show that while the parasites make exact copies of themselves while in mammals (cloning), they exchange genetic information during meiotic recombination, which happens in sexual reproduction, while in the sand fly.

Natalia S. Akopyants, Nicola Kimblin, Nagila Secundino, Rachel Patrick, Nathan Peters, Phillip Lawyer, Deborah E. Dobson, Stephen M. Beverley & David L. Sacks (2009). Demonstration of Genetic Exchange During Cyclical Development of Leishmania in the Sand Fly Vector. Science 324: 265-268.