HIV and the transmission of Leishmania.

In many countries, Leishmania/HIV co-infection is now changing the epidemiology of visceral leishmaniasis. The levels of transmission of the parasites causing such leishmaniasis were previously dependent on the conventional zoonotic cycle, in which sandflies transmitted the parasites from infected canids to other canids or humans. The co-infection, however, has led not only to marked increases in the sandfly transmission of the parasites from immunodepressed individuals directly to other humans but also, probably, to artificial transmission between immunodepressed intravenous-drug users, as the result of needle sharing.