Clinical presentations
In humans, there are three main clinical presentations:
Cutaneous leishmaniasis
- Localized cutaneous leishmaniasis: Leishmania infection is restricted to the skin. Lesions can be mild to severe depending on both the infecting species of and the immune response of the host. Localized cutaneous leishmaniasis is restricted to a single or a few lesions that either heal spontaneously or can be treated with anti- leishmanial drugs.
Etiological agents: L. major and L. tropica in the New World, some subspecies of the L. mexicana complex in the New World.
Distribution: 90% of all cases occur in Afghanistan, Brazil, Iran, Peru, Saudi Arabia and Syria, with1-1.5 million new cases reported annually worldwide.
- Diffuse cutaneous leishmaniasis: This exacerbated form occurs if Leishmania parasites disseminate over large portions of skin. This is a chronic form of leishmaniasis, and characterized by non-ulcerating, non-necrotizing skin lesions that spread over the body
Etiological agents: L. aethiopia in Ethiopia and Kenya and by various subspecies of L. mexicana in Central and South America.
Mucocutaneous leishmaniasis:
This clinical presentation usually begins as a cutaneous lesion that spreads to the mucosal tissue of the nose, mouth, and pharynx Manifestations of mucocutaneous leishmaniasis include chronic nasal symptoms, especially of the anterior nasal septum (leading to development of the characteristic "tapir nose") and progressing to extensive naso-oropharyngeal destruction. Secondary bacterial (or fungal) infections and associated problems are common.
Etiological agents: L. braziliensis.
Distribution: 90% of all cases occur in Bolivia, Brazil and Peru.
Visceral leishmaniasis or kala-azar:
This is a chronic and potentially fatal disease of the viscera (particularly the liver, spleen, bone marrow and lymph nodes). Visceral leishmaniasis can cause no or few symptoms but typically is associated with fever, loss of appetite (anorexia), fatigue, enlargement of the liver, spleen and nodes and suppression of the bone marrow. Visceral leishmaniasis also increases the risk of other secondary infections.
Etiological agents: Visceral leishmaniasis is most commonly caused by infection with L. donovani complex, which includes L. infantum (a.k.a. L. chagasi), but other species of Leishmania can visceralize (i.e. L. tropica).
Distribution: Of the 500,000 new cases of visceral which occur annually, 90% are in five countries: Bangladesh, Brazil, India, Nepal and Sudan.