Serodiagnosis of visceral and cutaneous leishmaniasis in human and canine populations living in Indigenous Reserves in the Brazilian Amazon Region

ABSTRACT INTRODUCTION: Leishmaniasis is endemic to the Northern, Northeastern, Central-Western, and Southeastern regions of Brazil. We aimed to assess the epidemiological situation of leishmaniasis in humans and dogs in indigenous villages located in the States of Mato Grosso and Tocantins using a serological survey conducted in May 2011. METHODS: Serum samples were collected from 470 humans and 327 dogs living in villages of the Urubu Branco and Tapirapé Karajá indigenous reserves. The samples were analyzed for the presence of Leishmania spp. antibodies using the indirect fluorescent antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA) with a crude antigen (CA) and soluble antigen (SA), and Dual Path Platform (DPP®) immunoassay for canine visceral leishmaniasis. RESULTS: Of 470 human samples tested, two (0.4%) were positive using IFAT. Among 327 dog samples tested, 28 (8.6%) were positive using ELISA CA, five (1.5%) using ELISA SA, two (0.6%) using IFAT, and none using DPP® immunoassay with Leishmania infantum chagasi antigen. When Leishmania amazonensis antigen was used, 20 (6.1%) samples were positive using ELISA CA and four (1.2%) using IFAT. CONCLUSIONS: There was a low prevalence of infection in the region, and significant differences among the main serological methods used for the diagnosis of leishmaniasis. These findings indicated that the detection of Leishmania spp. requires further study and improvement.

摘要：利什曼病在巴西北部、东北部、中西部与东南部地区均为地方性流行疾病。本研究依托2011年5月开展的血清学调查，旨在评估马托格罗索州（Mato Grosso）与托坎廷斯州（Tocantins）境内原住民村落中人类与犬只的利什曼病流行病学现状。
方法：研究人员从乌鲁布布兰科（Urubu Branco）与塔皮拉佩·卡拉雅（Tapirapé Karajá）原住民保留地的村落中，采集了470名人类与327只犬只的血清样本。采用间接荧光抗体试验（indirect fluorescent antibody test, IFAT）、以粗抗原（crude antigen, CA）与可溶性抗原（soluble antigen, SA）包被的酶联免疫吸附试验（enzyme-linked immunosorbent assay, ELISA），以及针对犬内脏利什曼病的双路径平台（Dual Path Platform, DPP®）免疫分析法，对样本中的利什曼属（Leishmania spp.）抗体进行检测。
结果：在470份受检人类样本中，经IFAT检测仅2份（0.4%）呈阳性反应。在327份受检犬只样本中，经ELISA CA检测有28份（8.6%）呈阳性，ELISA SA检测5份（1.5%）呈阳性，IFAT检测2份（0.6%）呈阳性；而使用杜氏利什曼原虫恰加斯亚种（Leishmania infantum chagasi）抗原的DPP®免疫分析法未检出阳性样本。当采用亚马逊利什曼原虫（Leishmania amazonensis）抗原时，ELISA CA检测有20份（6.1%）样本呈阳性，IFAT检测4份（1.2%）呈阳性。
结论：该区域的利什曼原虫感染率处于较低水平，且用于利什曼病诊断的主流血清学方法间存在显著差异。本研究结果提示，利什曼属病原体的检测仍需开展进一步研究与技术优化。