Epidemiology

According to the Global Burden of Disease Study from 2019, between 498,000 and 862,000 new cases of all forms of leishmaniasis are estimated to occur annually, resulting in up to 18,700 deaths and up to 1.6 million disability-adjusted life years lost.[14]

The leishmaniases are endemic in more than 90 countries in the tropics, neotropics, and southern Europe. An estimated 0.7 to 1 million cases are diagnosed each year.[15] According to the World Health Organization, over 1 billion people living in endemic areas are at risk of infection.[16]

Cutaneous leishmaniasis (CL) is the most common leishmanial syndrome worldwide. About 85% of global CL cases occur in Afghanistan, Algeria, Brazil, Colombia, Islamic Republic of Iran, Iraq, Pakistan, Peru, and the Syrian Arab Republic.​[17]​ An incidence of 18.4 cases per 100,000 population was reported in transmission areas of the Americas in 2020.[18] The global number of cases has been increasing, due to the adaptation of transmission cycles to peri-domestic environments, the spread to previously non-endemic areas due to urbanisation and deforestation, limited or non-existent vector or reservoir control programmes, improved diagnosis and case notification, increased detection of leishmaniasis associated with opportunistic infections (e.g., HIV/AIDS), and the emergence of anti-leishmanial drug resistance.[19][20]​ In developed countries, CL has also been reported in increasing numbers, most likely due to increased travel to CL-endemic areas as a result of tourism, military duty, or professional work.[21][22][23][24]​ Additionally, the incidence in the Americas decreased by 2% in 2020 compared with the previous year; El Salvador, Colombia, Guyana, and Mexico all reported decreases, whereas Guatemala, Peru, Costa Rica, and Paraguay reported an increase in cases.[18][25]​ Large outbreaks (i.e., >200,000 cases) of CL have been associated with sustained periods of conflict and the resulting collapse of health services (e.g., in Afghanistan and Syria).[26]

Visceral leishmaniasis (VL) is the most serious form of the disease and is fatal in over 95% of cases if left untreated. An estimated 50,000 to 90,000 new cases of VL occur globally each year.[15] About 97% of VL cases are reported from Brazil, Ethiopia, Eritrea, Kenya, India, Nepal, Somalia, South Sudan, Uganda, and Yemen.[17]​ An outbreak in Kenya was reported in early 2017.[27] In these countries, VL affects mainly poor people in rural areas. Several reports have documented the expansion of VL to urban areas (e.g., in Brazil).[28] In developed countries symptomatic VL is a rare disease, but may be found in returning military personnel from Iraq or Afghanistan or in migrants or visitors from endemic areas.[29][30][31]​ However, surveillance for asymptomatic Leishmania infantum (synonym: Leishmania chagasi) infection among Iraq-deployed US service members identified a 19.5% infection rate.[32] Fox hounds have been found to be infected by L infantum (synonym: L chagasi) in the eastern US, but autochthonous transmission to humans has yet to be described.[33]

WHO: leishmaniasis country profile Opens in new window

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