Pacheco Richard C, Horta Mauricio C, Moraes-Filho Jonas, Ataliba Alexandre C, Pinter Adriano, Labruna Marcelo B
Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brasil.
Biomedica. 2007 Sep;27(3):364-71.
In Brazil, capybaras (Hydrochoerus hydrochaeris) are important hosts for Amblyomma ticks, which in turn can transmit rickettsiae to humans and animals. Therefore, capybaras are potential sentinels for rickettsial infection.
The present study evaluated rickettsial infection in capybaras in different areas of the state of São Paulo, where rickettsiosis has never been reported. Materials and methods. Blood sera from 73 capybaras from six localities in São Paulo were tested by indirect immunofluorescence assay using Rickettsia rickettsii, Rickettsia parkeri, and Rickettsia bellii antigens. Capybara spleens were tested by PCR, targeting a fragment of the rickettsial gltA gene. Ticks were collected from each capybara sample and taxonomically identified to species.
A total of 94 positively reacting capybara samples, 19 (26.0%), 25 (34.2%), and 50 (68.5%) capybara sera reacted to R. rickettsii, R. parkeri, and R. bellii, respectively. Twenty-five capybara sera showed titers to R. bellii at least four-fold higher than to any of the other two antigens. These sera were considered homologous to R. bellii. Using the same criteria, 3 capybara sera were considered homologous to R. parkeri. No sera were be considered homologous to R. rickettsii. No rickettsial DNA was detected in capybara spleen samples. Ticks collected on capybaras were Amblyomma dubitatum and Amblyomma cajennense.
The first evidence is reported of R. bellii natural infection in vertebrate hosts, and the first evidence of R. parkeri infection in capybaras. While R. parkeri is known to infect and cause disease in humans, no similar evidence for human infection has been indicated by R. bellii.
在巴西，水豚（Hydrochoerus hydrochaeris）是钝缘蜱的重要宿主，而钝缘蜱又可将立克次氏体传播给人类和动物。因此，水豚是立克次氏体感染的潜在哨兵。
本研究评估了圣保罗州不同地区水豚的立克次氏体感染情况，这些地区此前从未报告过立克次体病。材料与方法。使用立氏立克次体、帕克立克次体和贝利立克次体抗原，通过间接免疫荧光法对来自圣保罗六个地区的73只水豚的血清进行检测。通过聚合酶链反应（PCR）检测水豚脾脏，以立克次氏体柠檬酸合酶基因（gltA）的片段为靶点。从每个水豚样本中采集蜱并进行分类鉴定。
共有94份水豚样本呈阳性反应，19份（26.0%）、25份（34.2%）和50份（68.5%）水豚血清分别对立氏立克次体、帕克立克次体和贝利立克次体有反应。25份水豚血清显示对贝利立克次体的滴度比对其他两种抗原中任何一种的滴度至少高四倍。这些血清被认为与贝利立克次体同源。使用相同标准，3份水豚血清被认为与帕克立克次体同源。没有血清被认为与立氏立克次体同源。在水豚脾脏样本中未检测到立克次氏体DNA。在水豚身上采集到的蜱为可疑钝缘蜱和卡延钝缘蜱。
报告了贝利立克次体在脊椎动物宿主中自然感染的首个证据，以及帕克立克次体在水豚中感染的首个证据。虽然已知帕克立克次体可感染人类并导致疾病，但贝利立克次体尚无类似人类感染的证据。
