Serosurvey of Rickettsia spp. in cats from a Brazilian spotted fever-endemic area

Abstract Rickettsia spp. bacteria are responsible for tick-borne diseases worldwide, mostly maintained by rickettsial amplifiers capybaras in Brazilian endemic areas. The campus of the University of São Paulo, in southeastern Brazil, is an area endemic for Brazilian spotted fever (BSF), with high density of capybaras and Amblyomma spp., along with confirmed human cases. Besides capybaras, the university has also an in-campus high population of sheltered and free-roaming cats. Accordingly, the aim of this study was to determine the prevalence and characteristics associated with Rickettsia rickettsii, Rickettsia parkeri and Rickettsia felis exposure among cats in a BSF-endemic area. Out of 51 cats sampled, 23/35 shelter (65.7%) and 5/16 free-roaming (31.2%) were positive (titers ≥ 64) for at least one Rickettsia species. Ticks species were present in 3/16 free-roaming cats (18.8%), consisting of Amblyomma spp., nymphs of Amblyomma sculptum and adult Rhipicephalus sanguineus sensu lato. Despite sharing the capybaras environment, the seropositivity among the free-roaming and shelter cats was lower than owned cats in other endemic areas. Whether equally or less exposed to rickettsial infection, compared with owned cats in endemic areas, free-roaming and shelter cats may be used as environmental sentinels for human exposure to rickettsiae in such areas.

摘要：立克次体属（Rickettsia spp.）细菌可引发全球范围内的蜱传传染病，在巴西流行地区主要由作为立克次体扩增宿主的水豚维持其传播循环。位于巴西东南部的圣保罗大学（University of São Paulo）校园是巴西斑点热（BSF）的流行区域，校内水豚与钝眼蜱属（Amblyomma spp.）种群密度较高，且已确诊存在人类感染病例。除水豚外，该校园内还存在大量收容猫与自由活动流浪猫种群。据此，本研究旨在明确该巴西斑点热流行区域内猫群对立氏立克次体（Rickettsia rickettsii）、帕克立克次体（Rickettsia parkeri）与猫立克次体（Rickettsia felis）的暴露率及其相关特征。本次共采集51只猫的样本，其中35只收容猫中有23只（65.7%）、16只自由活动流浪猫中有5只（31.2%）至少对1种立克次体属细菌呈血清阳性（抗体滴度≥64）。16只自由活动流浪猫中有3只（18.8%）携带蜱类，经鉴定为钝眼蜱属蜱虫、糙形钝眼蜱（Amblyomma sculptum）若虫以及广义血红扇头蜱（Rhipicephalus sanguineus sensu lato）成虫。尽管与水豚共享同一栖息环境，但本研究中自由活动流浪猫与收容猫的血清阳性率低于其他流行区域的家养猫。相较于流行区域的家养猫，无论本研究中的自由活动流浪猫与收容猫的立克次体感染暴露水平是否相当甚至更低，二者均可作为此类区域内人类立克次体暴露风险的环境哨兵。