2nd August 2023

Leishmaniasis

Leishmaniases are a group of diseases caused by the protozoa Leishmania and transmitted through sandflies. The disease can be classified into three forms: cutaneous (C), mucocutaneous (MC) and visceral (V).

Treatment is complex and often based on form (C/MC/V), region of infection (differences within the same species are found in different regions, which may predispose to transformation into other types of leishmaniasis) and patient factors.

Cutaneous

• Mainly caused by Leishmania tropica and Leishmania mexicana
• Incubation period of weeks to months
• Presents with pruritic papules at bite sites
• Progresses to a nodule, then a plaque, finally becoming a painless ulcer with an indurated border
  • Lesions can then crust over
• At risk of transformation to MC leishmaniasis years after initial infection
• Treatment is indicated if infection occurs in South or Central America and in the immunosuppressed

Mucocutaneous

• Mainly caused by Leishmania braziliensis
• Characterised by mucosal destruction mainly involving the nose and pharynx
• Treatment is with pentoxifylline

Visceral

• Also known as kala-azar due to the darkening of the skin seen with this disease
• Mainly caused by Leishmania donovani and Leishmania infantum
• Incubation period is usually 2 to 6 months but can be up to years
• Insidious onset over weeks of weight loss, fever and hepatosplenomegaly
• Replication occurs in the reticulo-endothelial system – resulting in dysfunction in the spleen, bone marrow and liver, leading to pancytopenia and liver disease
• Investigation of choice is bone marrow or splenic aspirate
• Liposomal amphotericin B is the first line treatment
• Post kala-azar dermal leishmaniasis, a chronic skin rash, is occasionally observed six months to two years following therapy for visceral leishmaniasis. Presents with red or hypopigmented macules similar to cutaneous manifestations of leprosy. Most cases are self-resolving.