Leishmaniasis

ing is slow, with the formation of scar tissue in a year or so.

The New World disease takes several different forms:

1. A self-limiting ulcer of 6 months' duration without metastases, caused by Leishmania tropica mexicana, is found in the Yucatan. It has a rodent reservoir in flat, low, rain forests.

2. Espundia, due to L. braziliensis, exists in the jungles of Panama through Amazonia to Paraguay. It starts as a painless ulcer and metastasizes to the oronasal or anorectal area in 5 to 23 years. The host is thought to be the paca (Cuniculus paca), a nocturnal American rodent.

3. A solitary ulcerative lesion known as uta, usually found at the base of the nose with no metastasis, exists in the Andean valleys of Peru and Argentina. The agent is Leishmania peruviana, and the host is the dog.

4. Leproid leishmaniasis is seen in Venezuela. It begins as a fleshy cutaneous nodule that slowly spreads over the body without ulcerating and is difficult to distinguish from leprosy. It is thought to be due to an immune response and is very chronic.

In the absence of demonstrable leishmania, reliance rests on the leishmanin skin test, which is positive in cutaneous disease when there is a tuberculoid histology. Generally it becomes positive early and remains so after healing is complete. Although most lesions are self-limiting, antimony, pyrimethamine, and amphotericin B are used to treat metastases. A persistent positive serology is an important sign of continued survival of the parasite, which may live for decades in asymptomatic individuals.

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