In-house serological ELISA as a leishmaniosis diagnostic test: development and applications in canines from the western border of Brazil

ABSTRACT: Leishmaniosis is a great public health problem affecting both humans and animals. The disease is caused by the protozoan Leishmania spp., which has a complex cycle involving a phlebotomine vector. The ELISA test (Enzyme-Linked Immunosorbent Assay) along with a chromatographic immunoassay was defined by the Brazil Health Ministry as the confirmatory screening protocol in 2011. Uruguaiana city is 630 km away from Porto Alegre, which makes it difficult to send samples and diagnose leishmaniasis, as well as receive quick results. In view of this, the present study evaluated an in-house indirect ELISA method compared to indirect immunofluorescence assay (IFA) and dual-path platform chromatographic immunoassay (DPP-BioManguinhos®) for the detection of an immune response to Leishmania spp. in canine species. The serological evaluation included 48 canines from the western border of Brazil (Uruguaiana and Barra do Quaraí city). Among the 48 canine samples tested, 18 were positive when using the ELISA technique, 19 were positive with IFA, and 17 were positive with rapid test DPP®. The ELISA technique showed a sensitivity/specificity of 83.3%/86.7% when compared to IFA and 100%/96.8% compared to DPP®. The present study showed a prevalence of 37.5%, demonstrating that the infection circulates in the studied population. It can be concluded that the ELISA technique was valuable for use in field conditions when performing screening tests in endemic areas.

摘要：利什曼病（Leishmaniosis）是一类严重威胁人类与动物健康的重大公共卫生问题。该病由利什曼原虫属（Leishmania spp.）原生动物引发，其完整生活史依赖白蛉媒介（phlebotomine vector）完成传播循环。2011年，巴西卫生部将酶联免疫吸附试验（Enzyme-Linked Immunosorbent Assay，ELISA）与层析免疫分析法（chromatographic immunoassay）联合方案确立为利什曼病的确认筛查流程。乌鲁瓜亚纳市（Uruguaiana）距阿雷格里港（Porto Alegre）630公里，这一地理距离导致样本寄送、利什曼病诊断及快速获取检测结果均面临诸多困难。鉴于此，本研究针对犬类利什曼原虫感染的免疫应答检测，构建了自建间接酶联免疫吸附试验方法，并与间接免疫荧光试验（indirect immunofluorescence assay，IFA）及双路径平台层析免疫分析法（dual-path platform chromatographic immunoassay，DPP-BioManguinhos®）开展对比评估。本次血清学评估共纳入48份采自巴西西部边境（乌鲁瓜亚纳市与巴拉杜夸赖市）的犬类样本。经检测，ELISA法检出阳性样本18份，IFA法检出19份，快速检测试剂DPP®则检出17份阳性样本。以IFA为参照标准时，ELISA法的灵敏度与特异性分别为83.3%与86.7%；以DPP®为参照标准时，其灵敏度与特异性可达100%与96.8%。本研究测得受试犬群的利什曼病感染率为37.5%，证实该病原体在研究种群中存在循环传播。综上，ELISA法具备优异的应用价值，可作为流行区现场筛查检测的可靠手段。