Combining diagnostic procedures for the management of leishmaniasis in areas with high prevalence of Leishmania guyanensis / Procedimentos diagnósticos combinados no manejo da leishmaniose em áreas com alta prevalência de Leishmania guyanensis

BACKGROUND: The Amazon region corresponds to approximately 40 percent of the cases of leishmaniasis in Brazil. We report a prospective study with 180 patients conducted in a health care unit that diagnoses 10 percent of the cases of leishmaniasis in the Brazilian Amazon. The study addresses how a combination of procedures improves diagnosis in areas with high prevalence of Leishmania guyanensis. OBJECTIVES: to evaluate diagnostic methods in areas with high prevalence of Leishmania guyanensis. METHODS: All subjects were amastigote-positive by direct microscopic examination of lesion scarifications. We conducted skin biopsy and histopathology, polymerase chain reaction and parasite cultivation. RESULTS: Polymerase chain reaction detected almost ninety percent of infections when two amplification protocols were used (mini-exon and HSP-70). HSP-70 specific polymerase chain reaction matched the sensitivity of parasite cultivation plus histopathology. CONCLUSION: The best combination was polymerase chain reaction plus histopathology, which increased diagnostic sensitivity to 94 percent. Species discrimination by polymerase chain reaction disclosed prevalence of human infections with Leishmania guyanensis of 94 percent and with Leishmania braziliensis of 6 percent for this region.

FUNDAMENTOS: O Amazonas corresponde a aproximadamente 40 por cento dos casos de leishmaniose do país. Nós reportamos um estudo prospectivo com 180 pacientes de uma unidade de saúde que diagnostica 10 por cento dos casos de leishmaniose da amazônia brasileira, com combinação de métodos diagnóstico em área de alta prevalência de Leishmania guyanensis. OBJETIVOS: avaliar métodos diagnóstico da Leishmaniose em área endêmica para Leishmania Amazonensis. MÉTODOS: Todos os pacientes tiveram exame direto positivo com presença de amastigotas. Foi feita também biópsia cutânea, com realização de exame histológico, reação em cadeia da polimerase e cultura. RESULTADO: A reação em cadeia da polimerase detectou aproximadamente 90 por cento de infecção quando foram usados duas técnicas de amplificação (mini-exon and HSP-70). A reação em cadeia da polimerase com HSP-70 foi mais sensível que a cultura associada à histopatologia. CONCLUSÃO: A melhor combinação foi a reação em cadeia da polimerase com histopatologia, com sensibilidade de 94 por cento. A discrimanação das espécies causadoras de infecção humana nessa região mostrou Leishmania guyanensis em 94 por cento dos casos e Leishmania brasiliensis em 6 por cento.

Frequency of Infection of Lutzomyia Phlebotomines with Leishmania braziliensis in a Brazilian endemic area as assessed by pinpoint capture and polymerase chain reaction

Leishmania infected of Lutzomyia spp. are rare in endemic areas. We tested the hypothesis that there is clustering of infected vectors by combining pinpoint capture with sensitive L. braziliensis kDNA minicircle specific PCR/dot blot in an endemic area in the State of Bahia. Thirty out of 335 samples (10 to 20 sand flies/sample; total of 4,027 female sand flies) were positive by PCR analysis and dot blot leading to a underestimated overall rate of 0.4 percent positive phlebotomines. However, 83.3 percent of the positive samples were contributed by a single sector out of four sectors of the whole studied area. This resulted in a rate of 1.5 percent Leishmania positive phlebotomines for this sector, far above rates of other sectors. Incidence of American cutaneous leishmaniasis cases for this sector was about twice that for other sectors. Our results show that there is a non-homogeneous distribution of Leishmania-infected vectors. Such a clustering may have implications in control strategies against leishmaniasis, and reinforces the necessity of understanding the ecological and geographical factors involved in leishmanial transmission