Magalhães-Junior Jairo Torres, Mota Tiago Feitosa, Porfirio-Passos Gabriela, Larangeira Daniela Farias, Franke Carlos Roberto, Barrouin-Melo Stella Maria
Laboratory of Veterinary Infectious Diseases, Hospital of Veterinary Medicine (Laboratório de Infectologia Veterinária, Hospital de Medicina Veterinária), Federal University of Bahia (Universidade Federal da Bahia-UFBA), Avenida Adhemar de Barros, 500, Ondina, ZIP: 40170-110 Salvador, Bahia, Brazil; Multidisciplinary Center of Barra, Federal University of Bahia West (UFOB), Barra, Bahia, Brazil.
Laboratory of Veterinary Infectious Diseases, Hospital of Veterinary Medicine (Laboratório de Infectologia Veterinária, Hospital de Medicina Veterinária), Federal University of Bahia (Universidade Federal da Bahia-UFBA), Avenida Adhemar de Barros, 500, Ondina, ZIP: 40170-110 Salvador, Bahia, Brazil.
Vet Parasitol. 2016 Jun 15;223:120-6. doi: 10.1016/j.vetpar.2016.04.031. Epub 2016 Apr 22.
One of the main limitations for the effective control of canine leishmaniasis in endemic areas is the difficulty in identifying infectious dogs. The objective of this study was to determine factors, related to dogs and to parasite detection in sand flies, which are associated with the positive xenodiagnosis of Leishmania infantum using the vector Lutzomyia longipalpis. The xenodiagnosis was performed in 50 owned dogs residing in endemic areas, which were divided into three different groups: G1-26 dogs proved to be infected and classified by severity of VL clinical signs on physical examination; G2-15 dogs proved to be infected and classified by severity of clinical signs and intensity of laboratory abnormalities; G3-nine dogs that were seropositive for anti-Leishmania IgG in ELISA tests. Parasite search in the sand flies after having fed on dogs in the xenodiagnosis was performed by both methodologies, PCR and dissection followed by microscopy. In G1, 58% (15/26) of dogs were able to transmit Leishmania to the vector, when parasite detection in sand flies were performed by PCR technique, 5 days after blood meal, whereas in G2, 53% (8/15) transmitted the parasite to the vector, however, confirmation was performed by direct observation of parasite through optical miscroscopy held 10 days after blood meal. Rate of infectiousness of dogs to sand flies was positively associated to severity of disease (p=0.042 and p=0.040), regardless the method used for clinical classification or for parasite detection in sand flies after xenodiagnosis. In G1 30% (3/10) of dogs with subclinical infection were infectious to the vector, while 80% (12/16) of dogs with clinical disease were also infectious. Even more, 17% (1/6) of dogs that had moderate disease were infectious to the sand flies, while 78% (7/9) of dogs with severe disease were infectious in G2. Still in G2, the proportion of sand flies infected (grade of infectiousness) was significantly lower (p=0.0098) when they fed on dogs with moderate disease (1%) in comparison with dogs with severe disease (38%). The dogs from G3 presented a rate of infectiousness of 11% (1/9), demonstrating that the indirect ELISA is not a good indicator of infectiousness and, therefore, should not be used as a confirmatory test for the euthanasia of dogs, as it is currently done in Brazil.
在流行地区有效控制犬利什曼病的主要限制之一是难以识别具有传染性的犬只。本研究的目的是确定与犬只以及白蛉体内寄生虫检测相关的因素，这些因素与使用长须罗蛉作为媒介对婴儿利什曼原虫进行阳性异种诊断有关。对居住在流行地区的50只家养犬进行了异种诊断，这些犬被分为三个不同的组：G1组 - 26只犬被证明感染，并根据体格检查中VL临床症状的严重程度进行分类；G2组 - 15只犬被证明感染，并根据临床症状的严重程度和实验室异常的强度进行分类；G3组 - 9只犬在ELISA试验中抗利什曼原虫IgG呈血清阳性。在异种诊断中犬只供血后，通过PCR和解剖后显微镜检查这两种方法在白蛉中进行寄生虫搜索。在G1组中，当在采血后5天通过PCR技术在白蛉中进行寄生虫检测时，58%（15/26）的犬能够将利什曼原虫传播给媒介，而在G2组中，53%（8/15）的犬将寄生虫传播给了媒介，然而，通过在采血后10天进行光学显微镜直接观察寄生虫来进行确认。无论用于临床分类的方法或异种诊断后在白蛉中进行寄生虫检测的方法如何，犬只对白蛉的感染率与疾病严重程度呈正相关（p = 0.042和p = 0.040）。在G1组中，30%（3/10）的亚临床感染犬对媒介具有传染性，而80%（12/16）的临床疾病犬也具有传染性。此外，在G2组中，17%（1/6）的中度疾病犬对白蛉具有传染性，而78%（7/9）的重度疾病犬具有传染性。同样在G2组中，与重度疾病犬（38%）相比，以中度疾病犬（1%）为供血对象时，感染白蛉的比例（感染等级）显著更低（p = 0.0098）。G3组的犬只感染率为11%（1/9），表明间接ELISA不是传染性的良好指标，因此，不应像巴西目前所做的那样，将其用作犬只安乐死的确诊试验。
