Leishmaniasis

Leishmaniasis refers to illness arising from infection by any species of the protozoan parasite Leishmania, not merely parasitic presence, since most infected persons never develop symptoms ^[1][2]. It is a vector-borne disease transmitted through the bite of infected female sandflies and encompasses cutaneous, visceral, and mucocutaneous presentations ^[1][2]. Cutaneous leishmaniasis is typically a zoonotic infection maintained in wild or semi-domesticated animal reservoirs such as rodents and dogs ^[5].

Cutaneous leishmaniasis produces skin lesions such as nodules, painless ulcers, crusted plaques, or ulcers on exposed body parts, sometimes numbering up to 200 and healing with permanent scars ^[1][2][5]. Visceral leishmaniasis (kala-azar) is life-threatening and marked by irregular fever, weight loss, anaemia, and enlargement of spleen and liver, with near-universal fatality if untreated ^[1][2]. Mucocutaneous leishmaniasis destroys mucous membranes of the nose, mouth, and throat, causing disability and social exclusion ^[1][2]. People living with HIV who acquire Leishmania infection face high likelihood of full disease, relapse, and death ^[4].

Leishmaniasis is endemic across almost 100 countries, with over 1 billion people at risk and cutaneous disease accounting for roughly 12 million existing and 2 million annual cases ^[3][2]. The Americas report about 80% of global cutaneous cases, and Brazil is the principal endemic country for visceral leishmaniasis in that region ^[4][2]. Visceral leishmaniasis is highly endemic in Iraq, Somalia, Sudan, and Yemen, while East Africa experiences frequent outbreaks of the visceral form and all types are endemic ^[4]. Cutaneous leishmaniasis is highly endemic in Algeria, whereas West Africa lacks sufficient epidemiological data, and imported cases mainly originate from Africa and the Americas ^[4]. Environmental and climatic changes, urbanization, deforestation, and migration further shape disease incidence and spread ^[4].

The parasites are transmitted to humans by the bite of infected female phlebotomine sandflies, tiny 2–3 mm insects that feed on blood to mature eggs ^[1][2]. More than 90 sandfly species are known vectors, and over 70 animal species including humans can serve as parasite reservoirs ^[4]. In most cases, cutaneous leishmaniasis is zoonotic, with transmission via Phlebotomus sandflies from rodent or dog reservoirs ^[5].

Control of leishmaniasis requires strengthened vector control, improved diagnostics, and development of safe and effective vaccines, which are currently lacking ^[3]. Because the disease primarily affects poor populations, commercial investment in diagnostics, drugs, and vaccines remains inadequate ^[3].

1. 1 World Health Organization. Leishmaniasis [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/news-room/questions-and-answers/item/leishmaniasis
2. 2 World Health Organization. Leishmaniasis [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/health-topics/leishmaniasis
3. 3 de Vries HJC et al. Cutaneous Leishmaniasis: A 2022 Updated Narrative Review into Diagnosis and Management Developments. Am J Clin Dermatol. 2022 Nov. PMID: 36103050. doi: 10.1007/s40257-022-00726-8. PubMed: https://pubmed.ncbi.nlm.nih.gov/36103050/
4. 4 World Health Organization. Leishmaniasis [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/news-room/fact-sheets/detail/leishmaniasis
5. 5 Mokni M et al. [Cutaneous leishmaniasis]. Ann Dermatol Venereol. 2019 Mar. PMID: 30879803. doi: 10.1016/j.annder.2019.02.002. PubMed: https://pubmed.ncbi.nlm.nih.gov/30879803/