L. braziliensis causes a natural infection in the large forest rodents of tropical Latin America. Sandflies transmit the infection to humans engaged in military activities, road builders opening jungle areas for new settlements, and others.
A primary skin lesion similar to oriental sore develops 1 to 4 weeks after sandfly exposure. Occasionally it undergoes spontaneous healing. More commonly, it progressively enlarges, often producing large vegetating lesions. After a period of weeks to years, painful, destructive, metastatic mucosal lesions of the mouth, nose, and occasionally the perineum, appear in 2 to 50% of patients. Sometimes, decades pass and the primary le-sion totally resolves before the metastases manifest themselves. Destruction of the nasal septum produces the characteristic tapir nose. Erosion of the hard palate and larynx may render the patient aphonic. In blacks, the lesions are often large, hypertrophic, polypoid masses that deform the lips and cheeks. Fever, anemia, weight loss, and secondary bacter-ial infections are common. Mucosal lesions caused by other Leishmania species may be seen following visceral dissemination in AIDS patients.
The diagnosis is made by finding the organisms in the lesions as described for localized cutaneous leishmaniasis. Because the propensity to metastasize to mucocutaneous sites is specific to certain species and subspecies, precise identification of the responsible organ-ism as described in the introduction is of clinical importance. The leishmanin skin test yields positive results, and most patients have detectable antibodies. As described for cu-taneous leishmaniasis, it is now possible to provide a rapid, direct, species-specific diag-nosis through the use of the PCR and probes to kinetoplast DNA.
Treatment is accomplished with the agents described later for kala azar. Advanced lesions are often refractory, and relapse is common. Cured patients are immune to reinfection. Control measures, other than insect repellents and screening of dwellings, are impractical because of the sylvatic nature of the disease.