Núcleo de Pós-Graduação e Pesquisa da Santa Casa de Belo Horizonte, MG, Brazil.
Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Microb Pathog. 2019 Jan;126:263-268. doi: 10.1016/j.micpath.2018.10.036. Epub 2018 Nov 9.
Visceral leishmaniasis (VL) is a zoonosis caused by the protozoa of the genus Leishmania. Among the species, L. infantum and/or L. infantum (chagasi) are the most important species affecting the Americas. Domestic dogs are the main reservoir of the parasite and participate effectively in the parasite' transmission cycle. The Canine Visceral Leishmaniasis Control Program (PCLV) adopted in Brazil present as strategies the vector control, health education and serological diagnosis of CVL in dogs followed by culling of the seropositive ones. The resolution to eliminate seropositive dogs by euthanasia, when necessary, are the most controversial and least accepted by society. The diagnostic methods for canine visceral leishmaniasis, currently indicated and approved in Brazil by the Ministry of Health from Brazil are the Dual Path Platform (DPP) as a screening test and the Enzyme immunoassay test (ELISA). This study aimed to verify the presence of Leishmania spp. DNA in peripheral blood samples of dogs presenting positive serological results byDPP and ELISA tests,throughreal-time polymerase chain reaction (rt-PCR), using the pair of primers 150-152 already described. For this purpose, were collected blood samples from 185 seropositive dogs among them, 41 (22%) exhibited some clinical signal of disease, whereas 144 (78%) was asymptomatic. The animals were also analyzed according to gender, race and hair size. According to the results of rt-PCR, it was observed that among the185 seropositive dogs analyzed, only 132 (71%) presented positive results for CVL and 53 (29%) presented negative results. From this, 41/41 symptomatic dogs were positive (100%), while among the asymptomatic dogs, 91/144 were positive (63, 2%) and 53/144 were negative (36, 8%). Concerning the hair size of seropositive dogs, we found that 41 (22%) had long hair, while 144 (78%) had short hair. No statistical significance occurred between the results of rt-PCR, ELISA and DPP tests and the profile of the animals (gender, size of the dogs and hair size), probably due to the small number of samples and the sampling differences of each profile. But statistical significance occurred between the results of rt-PCR and the clinical evaluation, since the rt-PCR was positive in all symptomatic dogs. Thus, through these results, we reached at the following question, which may contribute to an important current debate: the dogs presenting CVL seropositive diagnosis confirmed by tests distributed by the Ministry of Health were in reality ill or were they seropositive by living in an endemic area of the disease? Would these asymptomatic seropositive dogs spread the disease to the inhabitants even presenting a low parasite charge circulating in the blood.
内脏利什曼病（VL）是一种由利什曼原虫属的原生动物引起的人畜共患病。在这些物种中，L. infantum 和/或 L. infantum（chagasi）是影响美洲的最重要物种。家养狗是寄生虫的主要宿主，并有效地参与寄生虫的传播周期。巴西采用的犬内脏利什曼病控制计划（PCLV）采取了控制媒介、对犬进行卫生教育和血清学诊断内脏利什曼病以及随后扑杀血清阳性犬等策略。通过安乐死消除血清阳性犬的决议，在必要时，是最有争议和最不受社会接受的。巴西卫生部目前批准和推荐的犬内脏利什曼病诊断方法是双路径平台（DPP）作为筛选试验和酶联免疫吸附试验（ELISA）。本研究旨在通过实时聚合酶链反应（rt-PCR），使用已描述的引物 150-152，验证 DPP 和 ELISA 检测呈血清学阳性的犬外周血样本中存在利什曼属 spp.DNA。为此，从 185 只血清学阳性的犬中采集了血液样本，其中 41 只（22%）表现出一些疾病的临床信号，而 144 只（78%）无症状。这些动物还根据性别、种族和毛发大小进行了分析。根据 rt-PCR 的结果，观察到在分析的 185 只血清学阳性犬中，只有 132 只（71%）对 CVL 呈阳性，53 只（29%）呈阴性。从这一点来看，41/41 只症状性犬均为阳性（100%），而在无症状犬中，91/144 只呈阳性（63.2%），53/144 只呈阴性（36.8%）。关于血清学阳性犬的毛发大小，我们发现 41 只（22%）有长毛发，而 144 只（78%）有短毛发。rt-PCR 检测结果与动物（性别、犬只大小和毛发大小）的状况之间没有统计学意义，这可能是由于样本数量少，以及每种情况的采样差异所致。但是，rt-PCR 结果与临床评估之间存在统计学意义，因为所有症状性犬的 rt-PCR 均为阳性。因此，通过这些结果，我们提出了一个问题，这可能有助于当前的一个重要辩论：通过卫生部分发的测试确认患有 CVL 血清阳性诊断的犬实际上是患病了，还是因为它们生活在疾病的流行地区而呈血清阳性？这些无症状的血清阳性犬即使血液中循环的寄生虫载量较低，也会向居民传播疾病吗？
