Spotted fever group rickettsial infection in dogs and their ticks from domestic-wildlife interface areas in southeastern Brazil.

Rickettsia rickettsii is the causative agent of Brazilian spotted fever (BSF), for which humans and dogs are both susceptible. Dogs are sentinels in serological surveys, however, canine disease is rarely reported. Therefore, we aimed to evaluate natural infection by spotted fever group (SFG) Rickettsia spp. in dogs and ticks collected from domiciles close to forest fragments, featuring domestic-wildlife interface areas. Samples from 115 dogs and 135 ixodids were assessed by polymerase chain reactions (PCR) targeting the gltA gene for Rickettsia spp. and the ompA gene for the SFG rickettsial species. One dog (0.87%; 1/115) was positive for R. rickettsii. This dog presented nonspecific laboratory and clinical abnormalities (thrombocytopenia, hyperproteinemia, lymph node enlargement, emaciation, anorexia, and lethargy). Rickettsia parkeri was identified in 2.96% (4/135) of the ticks (Amblyomma sculptum, A. aureolatum, and Rhipicephalus sanguineus). This study confirmed the presence of SFG bacteria in non-endemic and preserved locations, where domestic and wild populations interact. We reinforce the fact that the dog is susceptible to natural R. rickettsii infection. Although this is a rare finding, preventive measures should be taken against BSF in the studied areas. Finally, R. parkeri infection is possibly being demonstrated in A. sculptum for the first time.

Spotted fever group rickettsial infection in dogs and their ticks from domestic-wildlife interface areas in southeastern Brazil / Infecção por rickettsias do Grupo da Febre Maculosa em cães e carrapatos de áreas de interface doméstico-silvestre no sudeste Brasileiro

Abstract Rickettsia rickettsii is the causative agent of Brazilian spotted fever (BSF), for which humans and dogs are both susceptible. Dogs are sentinels in serological surveys, however, canine disease is rarely reported. Therefore, we aimed to evaluate natural infection by spotted fever group (SFG) Rickettsia spp. in dogs and ticks collected from domiciles close to forest fragments, featuring domestic-wildlife interface areas. Samples from 115 dogs and 135 ixodids were assessed by polymerase chain reactions (PCR) targeting the gltA gene for Rickettsia spp. and the ompA gene for the SFG rickettsial species. One dog (0.87%; 1/115) was positive for R. rickettsii. This dog presented nonspecific laboratory and clinical abnormalities (thrombocytopenia, hyperproteinemia, lymph node enlargement, emaciation, anorexia, and lethargy). Rickettsia parkeri was identified in 2.96% (4/135) of the ticks (Amblyomma sculptum, A. aureolatum, and Rhipicephalus sanguineus). This study confirmed the presence of SFG bacteria in non-endemic and preserved locations, where domestic and wild populations interact. We reinforce the fact that the dog is susceptible to natural R. rickettsii infection. Although this is a rare finding, preventive measures should be taken against BSF in the studied areas. Finally, R. parkeri infection is possibly being demonstrated in A. sculptum for the first time.

Resumo Rickettsia rickettsii é o agente causador da Febre Maculosa Brasileira (FMB), doença na qual humanos e cães são susceptíveis. Os cães são sentinelas nos inquéritos sorológicos, contudo, a doença canina é raramente descrita. Assim sendo, objetivou-se avaliar a infecção natural por Rickettsia spp. do Grupo da Febre Maculosa (GFM) em cães e carrapatos obtidos de domicílios próximos a fragmentos de mata, caracterizando áreas de interface doméstico-silvestre. Amostras de 115 cães e 135 ixodídeos foram avaliadas pela reação em cadeia da polimerase (PCR) tendo como alvo o gene gltA de Rickettsia spp. e o gene ompA das espécies do GFM. Um cão (0,87%; 1/115) foi positivo para R. rickettsii. Este animal apresentou alterações clínicas e laboratoriais inespecíficas (trombocitopenia, hiperproteinemia, linfonodos edemaciados, emagrecimento, anorexia e letargia). Rickettsia parkeri foi identificada em 2,96% (4/135) dos carrapatos (Amblyomma sculptum, A. aureolatum e Rhipicephalus sanguineus). Este estudo confirmou a presença de bactérias do GFM em locais preservados e não endêmicos, onde populações domésticas e silvestres interagem. Reforçamos o fato do cão ser susceptível à infecção natural por R. rickettsii. Embora este seja um achado raro, medidas preventivas devem ser tomadas contra a FMB nas áreas estudadas. Em última análise, a infecção por R. parkeri possivelmente está sendo demonstrada pela primeira vez em A. sculptum.