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疾病，在巴西流行区域，水豚作为立克次体的扩增宿主维持了该菌的自然循环。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）的流行地带，境内分布有高密度的水豚与钝缘蜱属（Amblyomma spp.）种群，且已确诊多例人类病例。除水豚外，该校园内还栖息有大量收容猫与散养流浪猫。本研究旨在明确该巴西斑点热流行区内猫群的落基山斑点热立克次体（Rickettsia rickettsii）、帕克立克次体（Rickettsia parkeri）与猫立克次体（Rickettsia felis）暴露情况及其相关特征。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只散养流浪猫中有5只（31.2%）对至少一种立克次体属细菌呈血清学阳性（抗体滴度≥64）。16只散养流浪猫中有3只（18.8%）携带蜱虫，经鉴定为钝缘蜱属蜱虫、光滑钝缘蜱（Amblyomma sculptum）若虫以及广义血红扇头蜱（Rhipicephalus sanguineus sensu lato）成蜱。尽管与其他流行区域的家养猫共享水豚栖息环境，但本研究中流浪猫与收容猫的血清阳性率低于其他流行区的家养猫。无论与流行区家养猫相比暴露程度相当还是更低，散养流浪猫与收容猫均可作为此类区域内人类接触立克次体的环境哨兵。