Araes-Santos Ana Isabel, Moraes-Filho Jonas, Peixoto Renata M, Spolidorio Mariana G, Azevedo Sérgio S, Costa Mateus M, Labruna Marcelo B, Horta Mauricio C
1 Laboratório de Doenças Parasitárias, Universidade Federal do Vale do São Francisco , Petrolina, Pernambuco, Brazil .
2 Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo , São Paulo, São Paulo, Brazil .
Vector Borne Zoonotic Dis. 2015 Nov;15(11):645-51. doi: 10.1089/vbz.2015.1786.
This study investigated the prevalence of Rickettsia spp. and Ehrlichia canis infection in dogs and their ectoparasites from rural and urban areas of two municipalities, Petrolina and Juazeiro, within a semiarid region (Caatinga biome) of northeastern Brazil, by immunofluorescence assay (IFA) and polymerase chain reaction (PCR). Overall, 12.1% (61/504) and 23.0% (116/504) of canine plasma samples had antibodies reactive to Rickettsia spp. and E. canis. E. canis DNA was detected by PCR in 8.3% (42/504) of canine blood samples, whereas no blood sample was positive for Rickettsia spp. The infection by E. canis was determined by PCR in 4.9% (14/285) Rhipicephalus sanguineus sensu lato (s.l.) ticks and by Rickettsia felis in 1.1% (3/285) and 40.6% (74/182) ticks and fleas, respectively. Multivariate regression analyses revealed that canine seropositivity to Rickettsia spp. was associated statistically with the variables "to reside in Petrolina" and "presence of ectoparasites." Our results indicate that canine infection by E. canis might be endemic in the Caatinga biome as it is in other Brazilian biomes. Although no previous serosurvey for Rickettsia spp. has been conducted on dogs from the Caatinga biome, our values are much lower than the ones reported for rural dogs from other Brazilian biomes. These differences are likely related to the semiarid climate of the aatinga biome, which minimizes the exposure of rural dogs to Amblyomma spp. ticks, the most common vectors of Rickettsia spp. in Brazil. Considering that dogs are excellent sentinels for human exposure to Rickettsia spp., we can infer that the risks of human acquiring tick-borne rickettsiosis in the Caatinga region of the present study are low. The rickettsial infection rates in fleas and ticks were not related to canine seropositivity; i.e., areas with higher Rickettsia infection rates in fleas had the lowest canine seroreactivity to Rickettsia spp.
本研究通过免疫荧光测定法（IFA）和聚合酶链反应（PCR），调查了巴西东北部半干旱地区（卡廷加生物群落）两个城市佩特罗利纳和茹阿泽罗城乡地区犬类及其体表寄生虫中立克次体属和犬埃立克体感染的流行情况。总体而言，12.1%（61/504）的犬血浆样本对立克次体属有反应性抗体，23.0%（116/504）对犬埃立克体有反应性抗体。通过PCR在8.3%（42/504）的犬血样本中检测到犬埃立克体DNA，而没有血样对立克次体属呈阳性。通过PCR确定，在4.9%（14/285）的全沟硬蜱（广义）中检测到犬埃立克体感染，在1.1%（3/285）的蜱和40.6%（74/182）的跳蚤中检测到猫立克次体感染。多变量回归分析显示，犬对立克次体属的血清阳性与“居住在佩特罗利纳”和“存在体表寄生虫”变量在统计学上相关。我们的结果表明，犬埃立克体感染在卡廷加生物群落中可能与巴西其他生物群落一样呈地方流行。尽管此前尚未对来自卡廷加生物群落的犬进行立克次体属的血清学调查，但我们得到的值远低于巴西其他生物群落农村犬的报告值。这些差异可能与卡廷加生物群落的半干旱气候有关，这种气候使农村犬接触巴西最常见的立克次体属传播媒介——钝缘蜱属蜱的机会降至最低。鉴于犬是人类接触立克次体属的优秀哨兵，我们可以推断，在本研究的卡廷加地区，人类感染蜱传立克次体病的风险较低。跳蚤和蜱中的立克次体感染率与犬的血清阳性无关；即跳蚤中立克次体感染率较高的地区，犬对立克次体属的血清反应性最低。
