Old World cutaneous leishmaniasis (OWCL) is endemic in the Mediterranean basin, Africa (particularly in North and East Africa, with sporadic cases elsewhere), the Middle East, Central Asia, the Indian subcontinent, and China.
Cutaneous leishmaniasis results from infection of the skin with obligate intracellular parasites of the Leishmania genus. The parasites are transmitted by the bite of infected female phlebotomine sandflies (species in the Lutzomyia genus in the New World and in the Phlebotomus genus in the Old World). The World Health Organization (WHO) estimates that 1.5 million new cases of cutaneous leishmaniasis occur each year, and leishmaniasis is on the WHO’s list of neglected tropical diseases. Children are more frequently affected due to increased exposure to sandflies and underdeveloped immune systems. Over 90% of the cases occur in the following countries:
Afghanistan, Algeria, Iran, Iraq, Pakistan, Saudi Arabia, and Syria
Brazil and Peru
OWCL is most commonly caused by infection with Leishmania major and Leishmania tropica. Other species causing OWCL include Leishmania aethiopica, Leishmania infantum, and Leishmania donovani. In the Old World, female sandflies in the genus Phlebotomus carry Leishmania species. The reservoir hosts for the zoonotic Leishmania species include dogs, rodents, opossums, gerbils, hyraxes, and others. Infected humans are the reservoir hosts for L tropica, which is anthroponotic and often endemic in urban areas. Recent periods of civil unrest and armed conflicts, with resultant poor sanitation and vector control, are some of the factors associated with ongoing epidemics of OWCL in Afghanistan and Iraq.
Typically, the primary lesion starts as erythema at the site of a sandfly bite. Thereafter, it evolves, over weeks to months, from a papule to a nodule, which may then ulcerate with an elevated violaceous rim. Lymphangitis that ascends the lymphatic chain (sporotrichoid spread) and lymphadenopathy (sometimes bubonic) can be seen; the latter may precede the presence of skin lesions. Pruritus, pain, and bacterial superinfection may also be present. Systemic symptoms are rarely seen.
Multiple primary lesions on one part of the body may be seen; this can result from the probing behavior of sandflies as they attempt to get blood meals. Multiple lesions are more commonly noted in patients infected with L major than L tropica; up to 20 ulcers can be seen simultaneously in L major infection and fewer than 3 from L tropica. Ultimately, over months to years, lesions may heal without therapy, leaving hypopigmented, atrophic scars.
Chronic relapsing cutaneous leishmaniasis (leishmania recidivans) represents reactivation of infection. It is most commonly caused by L tropica and typically manifests as papules at the margins of scars, occurring months to years after clinical resolution of the initial ulcer.
Diffuse cutaneous leishmaniasis (DCL) is a rare variant caused by L aethiopica. It occurs in the context of leishmanial-specific anergy and is manifested by disseminated, nonulcerated lesions.