Gomes Aparecida H S, Ferreira Isabelle M R, Lima Maria L S R, Cunha Elaine A, Garcia Andrea S, Araújo Maria F L, Pereira-Chioccola Vera L
Laboratorio de Parasitologia, Instituto Adolfo Lutz, Av. Dr Arnaldo, CEP 01246-902, São Paulo, SP, Brazil.
Vet Parasitol. 2007 Mar 31;144(3-4):234-41. doi: 10.1016/j.vetpar.2006.10.008. Epub 2006 Dec 28.
Leishmaniases are endemic in many countries, mainly in rural areas. In Brazil, Leishmania infection is responsible for many cases of Leishmaniases, including recent reports in urban regions. Despite their sensitivity, traditional serological and parasitological methods for detecting Leishmaniases have proven inadequate for species discrimination. This study aimed to identify Leishmania species in biological samples by a fast methodology, avoiding "in vitro" cultivation. Knowledge of the Leishmania species is an important tool in regions where both New World visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) are prevalent. As these new foci appear in areas not traditionally endemic for VL, the main problem is to distinguish between true autochthonous infections and infections acquired in other well-known endemic areas. Since, domestic dogs are known to be the main VL and CL reservoir, they are regularly investigated in endemic areas to prevent, principally, severe and often fatal VL in humans. However, several infected dogs present no clinical signs or clinical signs similar to other canine diseases. Here, we evaluated the ability of PCR to diagnose VL and distinguish L. (L.) chagasi from other Leishmania species in domestic dogs. Samples from 114 dogs from 30 cities (Sao Paulo, Brazil) were divided into two groups: 44 symptomatic and 70 asymptomatic. They were assayed by parasitological methods (culture and microscopic examination) and PCR to determine L. (L.) chagasi, L. (V.) braziliensis; and in some cases, Leishmania spp. Parasitological tests and PCR-L. chagasi were concordant in 105 samples (92%). VL was confirmed in 49 dogs, while 56 had negative results. Of the 114 samples, 9 had discordant results, but were further tested by PCR-Leishmania spp. with positive results. VL was also confirmed in 4 dogs having negative parasitological tests and positive PCR-L. chagasi. Consequently, this PCR was positive for 100% (53/49) of dogs with parasites detected in parasitological tests. Also, PCR demonstrated high specificity detecting 61 dogs negative for VL. Leishmania infection was negative in 56 dogs, and 5 with positive culture and PCR-Leishmania spp. had CL since they were positive in PCR-L. braziliensis. This study shows the importance of including PCR in diagnosis of Leishmaniases by differential diagnosis contributing to the surveillance and control of VL programs.
利什曼病在许多国家呈地方性流行，主要发生在农村地区。在巴西，利什曼原虫感染导致了许多利什曼病病例，包括近期城市地区的报道。尽管传统的血清学和寄生虫学检测方法敏感度较高，但已证明不足以区分利什曼病的种类。本研究旨在通过一种快速方法在生物样本中鉴定利什曼原虫种类，避免“体外”培养。了解利什曼原虫种类是在新世界内脏利什曼病（VL）和皮肤利什曼病（CL）都流行的地区的一项重要工具。由于这些新疫源地出现在传统上非VL流行的地区，主要问题是区分真正的本地感染和在其他知名流行地区获得的感染。因为家犬是已知的主要VL和CL宿主，所以在流行地区定期对其进行调查，主要是为了预防人类严重且往往致命的VL。然而，一些感染犬没有临床症状或有与其他犬类疾病相似的临床症状。在此，我们评估了PCR诊断VL以及区分家犬体内的恰加斯利什曼原虫（L. (L.) chagasi）与其他利什曼原虫种类的能力。来自巴西圣保罗30个城市的114只犬的样本被分为两组：44只有症状的和70只无症状的。通过寄生虫学方法（培养和显微镜检查）和PCR对它们进行检测，以确定恰加斯利什曼原虫、巴西利什曼原虫（L. (V.) braziliensis）；在某些情况下，还检测利什曼原虫属。寄生虫学检测和PCR-恰加斯利什曼原虫在105个样本（92%）中结果一致。49只犬确诊为VL，而56只结果为阴性。在114个样本中，9个结果不一致，但通过PCR-利什曼原虫属进一步检测后结果为阳性。在4只寄生虫学检测阴性但PCR-恰加斯利什曼原虫阳性的犬中也确诊为VL。因此，对于寄生虫学检测中检测到寄生虫的犬，该PCR的阳性率为100%（53/49）。此外，PCR显示出高特异性，检测出61只犬VL为阴性。56只犬利什曼原虫感染为阴性，5只培养和PCR-利什曼原虫属阳性的犬患有CL，因为它们PCR-巴西利什曼原虫呈阳性。本研究表明，通过鉴别诊断将PCR纳入利什曼病诊断中对于VL项目的监测和控制具有重要意义。
