Laboratório de Parasitologia, Instituto Adolfo Lutz, Av Dr Arnaldo, 351 8 andar, CEP 01246-902 São Paulo, Brazil.
Parasitol Res. 2011 Aug;109(2):267-74. doi: 10.1007/s00436-010-2247-6. Epub 2011 Jan 11.
The occurrence of the insect vector (sand flies) with low rates of Leishmania infection, as well as autochthonous transmission in the absence of the natural vector in dogs, have been reported. These unexpected data suggest a hypothesis of other arthropods as a possible way of Leishmania transmission. The prevalence of Leishmania (Leishmania) infantum in fleas and ticks collected from dogs with canine visceral leishmaniasis (CVL), as well as parasite viability, were evaluated herein. The presence of L. (L.) infantum was assayed by PCR and ELISA in ectoparasites and biological samples from 73 dogs living in a Brazilian endemic area. As the occurrence of Leishmania DNA in ticks and fleas is expected given their blood-feeding habits, we next investigated whether parasites can remain viable inside ticks. PCR and ELISA confirmed that 83% of the dogs had CVL. Fleas and ticks (nymphs, male and female adults) were collected in 55% and 63% of the 73 dogs, respectively. Out of the 60 dogs with CVL, 80% harbored ectoparasites infected with L. (L.) infantum. The infection rates of the ectoparasites were 23% and 50% for fleas and ticks, respectively. The RNA analysis of the extract from ticks left in laboratory conditions during 7 to 10 days after removal from CVL dogs showed that parasites were alive. In addition, live parasites were also detected inside adult ticks recently molted in laboratory conditions. These findings indicate a higher infection rate of L. (L.) infantum in ticks and fleas, but they do not conclusively demonstrate whether these ticks can act as vectors of CVL, despite the fact that their rates were higher than those previously described in Lutzomyia longipalpis. The presence of viable L. (L.) infantum in ticks suggests the possible importance of dog ectoparasites in CVL dissemination.
已经报道了昆虫媒介(沙蝇)感染率低以及在没有天然媒介的情况下犬类中存在的内源性传播的情况。这些意外的数据表明,其他节肢动物可能是利什曼原虫传播的一种途径。本文评估了从患有内脏利什曼病(CVL)的犬中收集的跳蚤和蜱中的利什曼原虫(利什曼原虫)的流行率以及寄生虫的生存能力。通过 PCR 和 ELISA 检测了巴西流行地区 73 只犬的寄生虫和生物样本中的 L.(L.)婴儿的存在。鉴于它们的吸血习性,预计在跳蚤和蜱中会出现利什曼原虫 DNA,因此我们接下来研究了寄生虫是否可以在蜱中保持生存能力。PCR 和 ELISA 证实,83%的犬患有 CVL。在 73 只犬中,分别有 55%和 63%的犬收集了跳蚤和蜱(若虫,雄性和雌性成虫)。在患有 CVL 的 60 只犬中,80%携带感染 L.(L.)婴儿的外寄生虫。跳蚤和蜱的感染率分别为 23%和 50%。从患有 CVL 的犬中取出后,在实验室条件下放置 7 至 10 天的蜱的提取物的 RNA 分析表明寄生虫仍然存活。此外,在实验室条件下最近蜕皮的成年蜱中也检测到了活寄生虫。这些发现表明,L.(L.)婴儿在跳蚤和蜱中的感染率更高,但不能明确证明这些蜱是否可以作为 CVL 的媒介,尽管它们的感染率高于以前在 Lutzomyia longipalpis 中描述的感染率。在蜱中存在存活的 L.(L.)婴儿表明犬的外寄生虫在 CVL 传播中可能具有重要意义。
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