Situation and trends
The leishmaniases are a group of diseases caused by the protozoa parasite Leishmania. Over 20 Leishmania species known to be infective to humans are transmitted by the bite of infected female phlebotomine sandflies. There are three main types of leishmaniasis: i) visceral, often known as kala-azar and the most serious form of the disease (VL); ii) cutaneous, the most common (CL); and iii) mucocutaneous.
The disease mainly affects poor people in Africa, Asia and Latin America, and is associated with malnutrition, population displacement, poor housing, weak immune system and lack of resources. A recent review shows that over 98 countries and territories are endemic for leishmaniasis. It is estimated that approximately 0.2 to 0.4 million of new VL cases and 0.7 to 1.2 million of new CL cases occur each year worldwide. More than 90% of global VL cases occur in six countries: Bangladesh, Brazil, Ethiopia, India, South Sudan and Sudan.
Cutaneous leishmaniasis is more widely distributed, with about one-third of cases occurring in each of three epidemiological regions, the Americas, the Mediterranean basin, and western Asia from the Middle East to Central Asia. The ten countries with the highest estimated case counts are: Afghanistan, Algeria, Brazil, Colombia, Costa Rica, Ethiopia, Iran, Peru, Sudan and Syria, and together account for 70 to 75% of global estimated CL incidence.