Stefanetti Valentina, Morganti Giulia, Veronesi Fabrizia, Gavaudan Stefano, Capelli Gioia, Ravagnan Silvia, Antognoni Maria Teresa, Bianchi Flavia, Passamonti Fabrizio
1 Department of Veterinary Medicine, University of Perugia , Perugia, Italy .
2 Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche , Ancona, Italy .
Vector Borne Zoonotic Dis. 2018 Dec;18(12):704-708. doi: 10.1089/vbz.2018.2303. Epub 2018 Aug 21.
Dogs may be useful sentinels for public health monitoring of spotted fever group rickettsioses (SFGR). The aim of this study was to determine the exposure to SFGR among dogs and feeding ticks in central Italy. A total of 344 dogs and 607 adult ticks (395 Rhipicephalus sanguineus and 212 Ixodes ricinus specimens) collected from the coats of sampled animals were included in the study. Canine serum samples were analyzed by indirect fluorescent antibody technique (IFAT) for IgG antibodies against Rickettsia conorii and Rickettsia rickettsii. All the ticks and buffy coats were processed by a PCR targeting a fragment of gltA followed by sequencing. Overall, 56 dogs (16.3%) tested positive for one or both rickettsial antigens by IFAT with endpoint titers ranging from 1:64 to 1:2048; 38 (11%) serum samples reacted against R. conorii, 46 (13.4%) reacted against R. rickettsii, and 28 (8.1%) reacted simultaneously against both rickettsial agents. All buffy coats were PCR negative. Rickettsial DNA was revealed in 39 (18.4%) I. ricinus and in 10 (2.5%) R. sanguineus specimens. The amplicons sequencing showed three SFGR, that is, R. conorii detected in 10 R. sanguineus specimens and Rickettsia helvetica and Rickettsia monacensis detected in 7 and 32 I. ricinus ticks. Nine out of the 10 R. conorii isolates were obtained from ticks collected from seronegative dogs, and one specimen from a dog tested positive for both R. rickettsii and R. conorii by immunofluorescence assay. Among the seven ticks tested positive for R. helvetica, six were recovered from the coats of seronegative dogs and one from a dog having antibodies against R. conorii; the 32 isolates of R. monacensis were obtained from 28 seronegative and 4 R. conorii/R. rickettsii-positive dogs. The results highlight the non-negligible exposure of the canine population to SFGR in the sampled areas.
狗可能是用于斑点热群立克次体病（SFGR）公共卫生监测的有用哨兵。本研究的目的是确定意大利中部的狗和采食蜱中SFGR的暴露情况。研究共纳入了从采样动物体表采集的344只狗和607只成年蜱（395只血红扇头蜱和212只蓖麻硬蜱标本）。采用间接荧光抗体技术（IFAT）分析犬血清样本中抗康氏立克次体和立氏立克次体的IgG抗体。所有蜱和血沉棕黄层均通过针对gltA片段的PCR进行处理，随后进行测序。总体而言，56只狗（16.3%）通过IFAT检测出一种或两种立克次体抗原呈阳性，终点滴度范围为1:64至1:2048；38份（11%）血清样本与康氏立克次体反应，46份（13.4%）与立氏立克次体反应，28份（8.1%）同时与两种立克次体病原体反应。所有血沉棕黄层PCR均为阴性。在39只（18.4%）蓖麻硬蜱和10只（2.5%）血红扇头蜱标本中检测到立克次体DNA。扩增子测序显示三种SFGR，即在10只血红扇头蜱标本中检测到康氏立克次体，在7只和32只蓖麻硬蜱中分别检测到瑞士立克次体和蒙氏立克次体。10株康氏立克次体分离株中有9株来自从血清阴性的狗身上采集的蜱，1份标本来自一只通过免疫荧光试验检测立氏立克次体和康氏立克次体均呈阳性的狗。在7只检测出瑞士立克次体呈阳性的蜱中，6只从血清阴性的狗体表采集，1只从具有抗康氏立克次体抗体的狗身上采集；32株蒙氏立克次体分离株来自28只血清阴性的狗和4只康氏立克次体/立氏立克次体阳性的狗。结果突出了在采样地区犬类群体中SFGR的暴露情况不可忽视。
