Leishmaniasis is a protozoal infection transmitted by the bite of an infected sandfly. Over 21 species of
Leishmania cause infection in humans worldwide, resulting in three clinical phenotypes: cutaneous, mucocutaneous, and visceral disease. The clinical spectrum of cutaneous leishmaniasis (CL) varies widely and depends on the geographic site acquired, the infecting species, and the host immune status. Cutaneous disease typically begins as a papule that increases in size over weeks to months and becomes a shallow ulcer with a raised rim. Depending on the infecting
Leishmania species, people may develop localized (for example, because of
L. mexicana,
L. major, or
L. peruviana) or diffuse cutaneous involvement (for example, because of
L. amazonensis) or cutaneous involvement with potential to disseminate (for example, because of
L. Viannia braziliensis). Untreated lesions can self-resolve with scarring in 2–15 months (or longer) in immunocompetent persons.
1 Local intralesional treatments have been recommended for small, single lesions (< 5 cm) without lymph node metastasis caused by species that do not typically disseminate to the mucosa or viscera (e.g.,
L. mexicana). Systemic treatment is often indicated to reduce the risk of dissemination to the mucosa or viscera for certain species (e.g.,
L. V. braziliensis), decrease the time to healing, limit the morbidity caused by large or persistent skin lesions, and reduce the chance of relapse. Currently, the standard, first-line treatment of CL is intravenous (i.v.) sodium stibogluconate, 20 mg/kg per day, for 21 days.
2–4 Use of sodium stibogluconate, however, requires close monitoring for adverse effects such as arthralgias, myalgias, chemical pancreatitis, and elevated liver function tests, which occur in more than half of those treated.
5 Moreover, a poor response to therapy has been observed in 23.5% of primary CL cases treated with pentavalent antimonials.
6 Whether the poor response relates to insufficient drug levels (secondary to poor penetration into the skin or suboptimal dosing because of tolerability) or parasite resistance to drug therapy remains to be determined. Oral or short-course i.v. therapies are particularly attractive alternatives to a lengthy i.v. course of sodium stibogluconate, because it enables outpatient treatment of CL patients who feel otherwise well except for their skin lesions. Several non-antimony–based treatments (such as oral ketoconazole, oral miltefosine, and short-course i.v. liposomal amphotericin B) have the potential to be convenient, cost-effective, and less toxic alternatives to sodium stibogluconate.
A complicating feature of the treatment of CL is that the response to drugs (including pentavalent antimonials) varies depending on the infecting species and the geographic site of acquisition.
7 A species-specific treatment approach has increasingly been advocated for precisely this reason.
8 Commonly used methods for the diagnosis of
Leishmania, such as direct microscopic examination of clinical specimens and culture, do not identify the infecting species. Isoenzyme analysis has long been considered the gold standard for diagnosis of leishmaniasis to the species level.
9 This method, however, can be laborious and time-consuming, and it requires growth of
Leishmania promastigotes in culture, which can take several weeks. In recent years, molecular speciation by polymerase chain reaction (PCR) has been increasingly cited as a rapid and reliable method, with greater sensitivity than microscopic methods.
10,11 PCR can be performed directly on the clinical specimen, with results processed in a few hours, thus providing timely information to the clinician.
10–13In this single-center prospective case series, we used a species-specific treatment approach based on molecular identification of the infecting species by PCR in 10 patients with CL. An alternative non-antimony regimen was then chosen based on proven or likely efficacy against that species for CL or visceral disease. Our experience with this treatment approach and the efficacy and safety of these regimens is summarized here.