Serological study of feline leishmaniasis and molecular detection of Leishmania infantum and Leishmania braziliensis in cats (Felis catus)

Abstract Blood samples and swabs from ocular conjunctiva and mouth were obtained from 64 cats. Of 64 serum samples, 19 were positive for Leishmania antibodies by ELISA (29.80%). Eight cats were positive by PCR (12.5%) in swab samples from mouth and/or ocular mucosa. Poor kappa agreement between serological and molecular results (k = 0.16) was obtained. From five positive PCR samples one was L. braziliensis and four were L. infantum. Phylogenetic analysis performed with the five isolates of Leishmania, showed that samples of L. infantum isolated from the cats were phylogenetically close to those isolated from domestic dogs in Brazil, while the L. braziliensis is very similar to the one described in humans in Venezuela. The study demonstrated that, despite high seropositivity for Leishmania in cats living in the study region, poor agreement between serological and molecular results indicate that positive serology is not indicative of Leishmania infection in cats. Parasite DNA can be detected in ocular conjunctiva and oral swabs from cats, indicating that such samples could be used for diagnosis. Results of phylogenetic analyzes show that L. infantum circulating in Brazil is capable of infecting different hosts, demonstrating the parasite's ability to overcome the interspecies barrier.

摘要 本研究从64只家猫体内采集了血液样本、眼结膜拭子及口腔拭子。在64份血清样本中，19份经酶联免疫吸附试验（ELISA）检测出利什曼原虫（Leishmania）抗体阳性，阳性率达29.80%。对口腔及/或眼黏膜拭子样本开展检测时，8只家猫的聚合酶链式反应（PCR）结果呈阳性，阳性率为12.5%。血清学检测与分子生物学检测结果的科恩kappa一致性较差（κ=0.16）。在5份PCR阳性样本中，1份为巴西利什曼原虫（L. braziliensis），剩余4份为婴儿利什曼原虫（L. infantum）。对5株利什曼原虫分离株进行系统发育分析后发现，从家猫体内分离得到的婴儿利什曼原虫样本，与巴西家犬体内分离得到的同类菌株亲缘关系相近；而巴西利什曼原虫则与委内瑞拉人体中已报道的菌株高度相似。本研究表明，尽管研究区域内家猫的利什曼原虫血清阳性率较高，但血清学与分子检测结果的一致性较差，提示血清学检测阳性并不能作为家猫感染利什曼原虫的判定依据。可在家猫的眼结膜拭子及口腔拭子中检测到寄生虫DNA，表明此类样本可用于利什曼原虫感染的临床诊断。系统发育分析结果显示，在巴西流行的婴儿利什曼原虫可感染多种宿主，证实该寄生虫具备突破种间屏障的能力。