Human Leishmaniasis (Zoonosis) Delhi boil, Aleppo button, Gafsa sore, kala-azar, espundia

• Twenty three species of Leishmania cause disease in humans. Depending upon the species and the reaction of the individual, several different syndromes are seen, the commonest of which are visceral leishmaniasis (which is usually fatal if not treated), cutaneous leishmaniasis (which will usually self cure eventually, leaving unsightly scars) and mucocutaneous leishmaniasis (of Latin America; treatment is frequently unsuccessful).
• Other clinical manifestations include post kala-azar dermal leishmaniasis; Sudanese oronasal leishmaniasis and disseminated anergic leishmaniasis.

Presenting signs

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• Visceral leishmaniasis: irregular fever; splenomegaly; hepatomegaly; abdominal swelling and pain; diarrhoea; cough; weight loss; lymphadenopathy; anaemia; jaundice; oedema; ascites; spontaneous haemorrages.
• Cutaneous leishmaniasis: erythematous papule developing into a nodule-plaque with a seropurulent discharge that dries forming a crust; removal of the crust reveals a typical crater-form ulcer; unless contaminated with bacteria, it is painless; inflammatory satellite papules often present with some leishmanial species; regional lymphadenopathy common with American species of Leishmania.
• Mucocutaneous leishmaniasis: a sequel of one or more cutaneous lesions after spontaneous healing associated mostly with L braziliensis of the New World; early signs include epistaxis and difficulty in sleeping because of nasal congestion; if non-ulcerative, there are frequently nasal polyps and progressive enlargement of the upper lip and nose followed by a drooping nose caused by destruction of the cartilage; perforation of the anterior septum is pathognomic; if ulcerative, there is rapid destruction of the nose and upper palate, a syndrome most common in black patients.

Geographic distribution

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• Human leishmaniasis is found in southern Europe, and parts of Africa, Asia and the Americas. See maps in notes for distribution.
• Reliable figures for the annual incidence of each form of leishmaniasis are not available as they are not notifiable diseases in all countries in which they occur. Even in many endemic countries where they are notifiable diseases, not all cases are notified and the data are underestimates.

Distribution of Leishmania species causing
human visceral leishmaniasis

Distribution of cutaneous leishmaniass caused
by L. tropica and related species in the Old World

Distribution of cutaneous leishmaniass caused
by L. major with a rodent reservoir in the Old World

Distribution of Leishmania species causing
cutaneous leishmaniasis in Central and South America.

Distribution of Leishmania (Viannia) species causing cutaneous
and mucocutaneous leishmaniasis in Central and South America.

Age predisposition

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• Ubiquitous.

Public Health considerations

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• WHO estimated that the global prevalence of all forms of these diseases is 12 million cases and that the annual incidence is 1.5 - 2 million cases. Of human diseases caused by protozoal parasites, visceral leishmaniasis alone comes second in public health importance (after malaria) as measured by DALYs (Disability Adjusted Life Years).

Definitive Diagnostic features

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• The gold standard for the diagnosis of all forms of human leishmaniasis is the demonstration of the parasite. This is done by examining stained smears of bone marrow or spleen tissue (visceral leishmaniasis), or tissue taken from the edge of a cutaneous lesion (all forms of cutaneous leishmaniasis), or nasal mucosa (mucocutaneous leishmaniasis). Amastigotes in such samples can be cultured as promastigotes in many different culture media, the commonest of which is NNN. Culturing reveals more cases than stained smears.
• PCR to reveal the presence of leishmanial DNA is being used increasingly.
• In visceral leishmaniasis, rising titres of leishmanial antibodies are diagnostic; the commonest methods for this are the ELISA and the IFAT.
• Delayed hypersensitivity to the intradermal leishmanin skin test confirms infection but is negative in early stages of visceral leishmaniasis and may not become positive in some cases of Old World cutaneous leishmaniasis.

Sources

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Refereed papers

• Markle W H & Makhoul K (2004) Cutaneous leishmaniasis: recognition and treatment. Am Fam Physician. 69, 1455-1460.
• Prasad R, Kumar R, Jaiswal B P & Singh U K (2004) Miltefosine: an oral drug for visceral leishmaniasis. Indian J Pediatr. 71, 143-144.
• Allahverdiyev A M, Uzun S, Bagirova M, Durdu M & Memisoglu H R (2004) A sensitive new microculture method for diagnosis of cutaneous leishmaniasis. Am J Trop Med Hyg. 70, 294-297.
• Blum J, Desjeux P, Schwartz E, Beck B & Hatz C (2004) Treatment of cutaneous leishmaniasis among travellers. J Antimicrob Chemother. 53, 158-166.
• Friedman R, Hanson S & Goldberg L H (2003) Squamous cell carcinoma arising in a Leishmania scar. Dermatol Surg. 29, 1148-1149.
• Salman S M, Rubeiz N G & Kibbi A-G (1999) Cutaneous leishmaniasis: clinical features and diagnosis. Clinics in Dermatology 17, 291-296.

Other sources of information

• Peters, W. & Killick-Kendrick, R. (Eds) (1987). The Leishmaniases in Biology and Medicine, London:Academic Press, 2 volumes.

Vetstream contributor(s)

• Professor Robert Killick-Kendrick MPhil, PhD, DSc, DIC, FIBiol, Department of Biological Sciences, Imperial College of Science, Technology and Medicine, London, UK.