Cutaneous leishmaniasis
From Wikipedia, the free encyclopedia
Cutaneous leishmaniasis is the most common form of leishmaniasis. It is a skin infection caused by a single-celled parasite that is transmitted by sand-fly bites. There are about 20 species of Leishmania that may cause cutaneous leishmaniasis.
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[edit] Epidemiology
Cutaneous leishmaniasis endemic to many parts of the world. Around twenty different species of Leishmania parasite are capable of infecting humans. The distribution of cutaneous leishmaniasis is very tightly linked to geography and villages even 15 miles apart can have very different rates of cutaneous leishmaniasis.
Some Leishmania species are closely linked to humans and are therefore found in cities (e.g., L. tropica), whereas some are more traditionally associated with animal species and are therefore considered zoonoses (e.g., L. major). Some species that are traditionally considered zoonotic (e.g., L. panamensis) may be becoming primarily human diseases.[1]
[edit] Pathology
Promastigotes of leishmania are transmitted to human skin by the bite of a sandfly. Leishmania then invades human macrophages and replicates intracellularly.
A raised, red lesion develops at the site of the bite (often weeks or sometimes years afterwards). The lesion then ulcerates and may become secondarily infected with bacteria. In many species (for example, L. major) the lesion often spontaneously heals with atrophic scarring. In some species (for example, L. viannia braziliensis) the lesion may spontaneously heal with scarring, but then re-appear elsewhere (especially as destructive mucocutaneous lesions). Lesions of other leishmania species may spontaneously heal and then re-appear as satellite lesions around the site of the original lesion, or along the route of lymphatic drainage.
Some species tend to cause cutaneous leishmaniasis (e.g., L. major and L. tropica), whereas some species tend to cause visceral leishmaniasis (e.g., L. infantum and L donovani).
[edit] Post kala-azar dermal leishmaniasis
Species that usually cause visceral leishmaniasis (for example, L. infantum or L. donovani) after full and adequate treatment may then re-appear as multiple raised skin lesions called "post kala-azar dermal leishmaniasis". This is not a result of inadequate treatment of visceral leishmaniasis. The skin lesions will respond to retreatment.
[edit] Mucocutaneous leishmaniasis
Mucocutaneous leishmaniasis is the most feared form of cutaneous leishmaniasis because it produces destructive and disfiguring lesions of the face. it is most often caused by Leishmania viannia braziliensis, and L. aethiopica has also been rarely described.
[edit] Treatment
The evidence for optimal treatment of cutaneous leishmaniasis is patchy. Treatments that work for one species of leishmania may not work for another; it is recommended that advice of a tropical medicine or geographical medicine specialist be sought. Ideally, every effort should be made to establish the species of leishmania by molecular techniques. In the setting of a developing country, there is often only one species present in a particular locality, so it is usually unnecessary to speciate every infection. Unfortunately, leishmaniasis is an orphan disease, and almost all the current treatment options are toxic, with significant side-effects.
Leishmania major
- Treatment of L. major infections are often considered to heal spontanously There are meanwhile several reports of severe cases caused by L.major in Afghanistan. Also cases now reported from cutaneus leishmanaisis caused by L.infantum!
- Leishmania (Vianna) braziliensis
- Treatment is mandatory because of the risk of developing mucocutaneous lesions.
pentavalent antimonials are currently worldwide the treatments of choice.In some areas of Latin America Amphotericin has become more important.
New treatment option are arising from the new oral drug Miltefosine (Impavido®) which has shown in several clinical trial to be very efficient and safe in visceral and cutanous leishmaniasis. Recent studies from Boliva show a high cure rate for mucocutaneous leishmaniasis. First comperative studies versus pentavalent antimonials in Iran and Pakistan show also a high cure rate for L.major and L.tropica. It is registered in many countries of Latin America (e.g. Colombia) as well in Germany, the home country of the originator Zentaris GmbH. In October 2006 it received orphan drug status from the US Food and Drug administration. The drug is generally better tolerated than other drugs. Main side effects are gastrointetinal disturbance in the 1-2 days of treatment which does not affect the efficacy.
Secondary bacterial infection (especially with Staphylococcus aureus) is common and may require antibiotics.
[edit] References
- ^ Vergel C, Palacios R, Cadena H, et al. (2006). "Evidence for Leishmania (Viannia) parasites in the skin and blood of patients before and after treatment". J Infect Dis 194: 503–511.
