Leishmaniasis includes two major diseases, cutaneous leishmaniasis and visceral leishmaniasis, caused by more than 20 different leishmanial species.
Cutaneous leishmaniasis, the most common form of the disease, causes skin ulcers. Visceral leishmaniasis causes a severe systemic disease that is usually fatal without treatment. Mucocutaneous leishmaniasis is a rare but severe form affecting the nasal and oral mucosa.
Leishmaniasis is transmitted by the bite of small insects called sand flies. Many leishmanial species infect animals as well as humans. The distribution is world-wide, but 90% of visceral leishmaniasis cases occur in India, Bangladesh, Nepal, Sudan, Ethiopia and Brazil, while 90% of cutaneous leishmaniasis cases occur in Afghanistan, Algeria, Iran, Saudi Arabia, Syria, Brazil, Colombia, Peru and Bolivia.