Cutaneous leishmaniasis is the most common form of leishmaniasis. It is a skin infection caused by a single celled parasite that is transmitted by sandfly bites. There are about 20 species of Leishmania that may cause 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.
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 atrophy 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.
Current approach to diagnosis involves 1. demonstration of parasite by microscopy, in vitro culture or animal inoculation, 2. immuno diagnosis of parasite antigen, 3.detection of parasite DNA in tissue. Newer PCR based tools have higher sensitivity and specificity. Emergence of PKLD has been reported in HIV affected individuals and may become a problem in future.
Sodium stibogluconate (SSG) alone or in combination with rifampicin is used for the treatment of PKLD for a long course up to 4 month. Compliance can be an issue for such long course.
Mucocutaneous leishmaniasis is treated with long courses (e.g. 30 days) of pentavalent antimonials in high dose (20 mg/kg). This may fail to cure up to 42% of patients even in those patients who achieve an apparent cure, as many as 19% will relapse.. Several drug combinations with immunomodulators have been tested, for example, a combination of pentoxifylline (inhibitor of TNF-α) and a pentavalent antimonial at high-dose for 30 days in a small-scale (23 patients) randomised placebo-controlled study from Brasil achieved cure rates of 90% and reduced time to cure, a result that should be interpreted cautiously in light of inherent limitations of small-scale studies. In an earlier small-scale (12 patients) study addition of imiquimod showed promising results which need yet to be confirmed in larger studies.
New treatment options are arising from the new oral drug Miltefosine (Impavido) which has shown in several clinical trials to be very efficient and safe in visceral and cutaneous leishmaniasis. Recent studies from Bolivia show a high cure rate for mucocutaneous leishmaniasis. Comparative studies against pentavalent antimonials in Iran and Pakistan are also beginning to show 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 its developer 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 gastrointestinal disturbances 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. Unfortunately, clinicians who are unfamiliar with cutaneous leishmaniasis may mistake the lesion for a pure bacterial infection (especially after isolation of S. aureus from bacterial skin swabs) and fail to consider the possibility of leishmaniasis.