Leishmaniasis

Leishmaniasis comprises a group of diseases caused by protozoan parasites of the genus Leishmania, with more than 20 species capable of infecting humans. The parasites are transmitted to humans through the bite of infected female phlebotomine sandflies—tiny insects measuring 2–3 millimeters in length. The disease is classified under ICD-10 code B55 and ICD-11 code 1F51. The term leishmaniasis specifically denotes the condition of developing illness due to Leishmania infection, as most infected individuals remain asymptomatic throughout their lives.

The disease presents in three distinct clinical forms. Cutaneous leishmaniasis, the most common manifestation, produces ulcerative lesions on exposed body parts including the face, arms, and legs; patients may develop anywhere from a single lesion to as many as 200, which can cause serious disability and leave permanent scars leading to social stigmatization. Visceral leishmaniasis, also known as kala-azar, is the most severe form and is characterized by irregular fever, substantial weight loss, hepatosplenomegaly, and profound anemia; without treatment, fatality rates approach 100% within two years. Mucocutaneous leishmaniasis is the most disabling form, progressively destroying the mucous membranes of the nose, mouth, and throat. Post-kala-azar dermal leishmaniasis represents a cutaneous sequela that typically appears as macular, papular, or nodular rashes on the face, upper arms, and trunk, predominantly in East African patients following treated visceral infection.

Leishmaniasis is endemic across tropical and subtropical regions of Africa, Asia, the Americas, and southern Europe, with more than one billion people living in areas at risk of infection. The Eastern Mediterranean region accounts for approximately 80% of global cutaneous leishmaniasis cases, while visceral leishmaniasis is highly endemic in Iraq, Somalia, Sudan, and Yemen. In the African region, cutaneous leishmaniasis is highly endemic in Algeria, whereas epidemiological data for West Africa remain limited; East Africa demonstrates endemicity for all three forms with frequent visceral leishmaniasis outbreaks. The Americas region, particularly Brazil, represents the primary focus for visceral leishmaniasis in that hemisphere, with complex epidemiology involving multiple animal reservoirs, sandfly vectors, and Leishmania species. Imported cases are commonly reported in the European region, predominantly originating from Africa and the Americas.

Leishmaniasis is transmitted through the bite of infected female phlebotomine sandflies, which require blood meals to produce eggs. Over 90 sandfly species have been identified as competent vectors, with Phlebotomus species serving as primary vectors in the Old World and Lutzomyia species in the New World. The transmission cycle involves multiple reservoir hosts, with approximately 70 animal species—including humans—capable of serving as sources of Leishmania parasites. The complexity of zoonotic and anthroponotic transmission cycles varies considerably by geographic region and Leishmania species.

Populations residing in endemic areas face the highest risk of infection, with over one billion people living in regions where leishmaniasis is established. Risk factors for acquisition include poverty, malnutrition, deforestation, and urbanization, which influence both vector abundance and human exposure. Individuals with immunosuppression may experience more severe disease manifestations. The permanent scarring from cutaneous lesions disproportionately affects women and girls in many endemic societies due to associated stigmatization.

Prevention strategies focus on vector control and personal protection measures. Insecticide-treated bed nets provide a physical and chemical barrier against sandfly bites, while indoor residual spraying campaigns can reduce sandfly populations in endemic areas. Early detection and treatment of active cases serve to reduce morbidity and interrupt transmission cycles. The specific treatment regimen depends on the geographic origin of infection, the infecting Leishmania species, and the clinical form of disease.

Leishmaniasis surveillance must account for the disease's complex epidemiological heterogeneity across regions and its multiple clinical manifestations. The distinction between infection (which is often asymptomatic) and disease is critical for accurate case reporting. Given that cutaneous leishmaniasis represents the predominant form globally while visceral leishmaniasis drives mortality, surveillance systems should capture both case counts and disease severity. Cross-border movement and imported cases warrant particular attention in non-endemic regions, especially where competent vector species may be present.

1. 1 WHO Health Topics. Leishmaniasis.
2. 2 WHO Fact Sheet. Leishmaniasis.
3. 3 WHO Q&A. Leishmaniasis.
4. 4 Wikidata. cutaneous leishmaniasis.
5. 5 Wikipedia. Leishmaniasis - Wikipedia.

ICD-10

B55

ICD-11

1F51

Total cases

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Peak month

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Coverage

0 reporting countries · —