AIDS and leishmaniasis.

Transmission ofLeishmania Leishmania are protozoal parasites carried from one infected host to another by sandflies. Leishmania cause a range of cutaneous, mucocutaneous, and systemic (visceral) diseases in humans and animals. In Europe L infantum is enzootic among domestic dogs in the Mediterranean littoral, where approximately 10-30% of pet dogs have clinical or serological evidence of leishmaniasis.' 2 Dogs are generally unable to mount an effective cellular immune response against L infantum, so parasites remain in skin lesions, in circulation, or in tissue macrophages permanently. Canine leishmaniasis responds poorly to treatment, typically running a chronic, relapsing course until the parasites become unresponsive and the animal dies. Clinical leishmaniasis among immunocompetent humans is more than 1000-fold rarer than canine leishmaniasis, with only about 500 infections occurring annually in the Mediterranean area; children are mainly affected. Transmission of L infantum occurs during the summer and is focal, with small zones of transmission in suburban and semirural areas.