Cutaneous leishmaniasis due to Leishmania (Leishmania) amazonensis in Amazonian Brazil, and the significance of a negative Montenegro skin-test in human infections

Abstract

The clinical and epidemiological features of 62 cases of cutaneous leishmaniasis due to Leishmania (Leishmania) amazonensis, from Pará State, Amazonian Brazil, are discussed. The parasite, isolated in hamster skin and/or blood-agar culture medium, was in each case identified by both biological characteristics and a monoclonal antibody specific for promastigotes of L. (L.) amazonensis. Of the 62 patients, 46 (74.2%) presented with a single cutaneous lesion, and on no occasion was evidence found indicating metastatic spread to either the naso-pharyngeal mucosae or the viscera. Recent claims that this parasite may be responsible for both mucocutaneous leishmaniasis and typical visceral leishmaniasis are discussed. Meglumine antimoniate (Glucantime) proved highly efficient in the treatment of all patients. Of the 62 patients examined by the Montenegro skin test, only 32 (51.6%) gave a positive reaction. The significance of this finding is considered and the hypothesis made that the parasite itself may induce an immunoinhibition. Field studies amply confirmed the role of Lutzomyia flaviscutellata as the major sandfly vector of L. (L.) amazonensis in Amazonia.

Ecology of the Leishmania Species in the Guianan Ecoregion Complex

“…Diffuse cutaneous leishmaniasis is not common in the GEC. 22 Cases caused by L. (L.) amazonensis have been reported in Brazil, mainly in the Amazon River basin (states of Pará, Amapá, and Amazonas) 12,23,43,51 and in Venezuela. 23,43 Interestingly, DCL was also shown to be caused by L. (L.) venezuelensis but not strictly in the GEC.…”

“…61 In the states of Amazonas, Pará, Rondônia, and Acre, the infection rate in the Nyssomyia subgenus was approximately 7.5%, which emphasizes the crucial role of this sub-genus in the transmission of the parasite. 51,141,142 In French Guiana, Lu. flaviscutellata, formerly known as Phlebotomus apicalis, was shown to be distributed throughout this country, [143][144][145][146] and was also infected with L. (L.) amazonensis 46,140 at a rate similar to that reported in Pará (approximately 0.5%).…”

“…flaviscutellata. 51,147 Reservoir hosts. This zoophilic sand fly is abundant in secondary forests soils.…”

An outbreak of cutaneous leishmaniasis among soldiers in Belém, Pará State, Brazil, caused byLeishmania (Viannia) lindenbergin. sp.

“…The clinical details of these cases are given in Table I. LABORATORY DIAGNOSIS All patients were submitted to the following proce dures: a) smears of exudate from the border of lesions were air dried, fixed in absolute methyl alcohol, and stained by Giemsa's method to confirm the presence of leishmanial amastigotes; b) intradermal Montenegro skin tests were performed with leishmanin antigen to evaluate the delayed hypersensitivity cellular response according to Silveira et al (1991c); and c) biopsies were triturated in physiological saline for intradermal inoculation into the hind feet of pairs of hamsters, which were examined at weekly intervals for the deve lopment of cutaneous lesions containing leishmanial amastigotes.…”

Avaliação do poder sensibilizante da reação de Montenegro

“…Resultados falsos negativos também têm sido descritos quando a infecção é precoce 8 , ou em casos em que a doença cutânea seja causada por Leishmania amazonensis 37 . Apesar do teste de Montenegro ser plenamente aceito, diferenças na preparação comercial podem afetar a antigenicidade e a eficácia na detecção de diversas formas de leishmaniose em diferentes áreas geográficas 1 2 .…”