Serological evidence of Rickettsia in horses from a semi-arid Brazilian region

Abstract

Brazilian spotted fever (BSF) is a common tick-borne disease caused by Rickettsia rickettsii. Horses are the primary hosts of the main vector, Amblyomma sculptum, and are considered efficient sentinels for circulation of Rickettsia. Therefore, the aim of this study was to detect antibodies reactive to R. rickettsii antigens in horses from a non-endemic area in the north-central region of Bahia state, Brazil. Blood samples and ticks were collected from 70 horses from the municipalities of Senhor do Bonfim, Antônio Gonçalves, Pindobaçu, and Campo Formoso. The sera obtained were tested by an indirect immunofluorescence assay to detect anti-Rickettsia antibodies. Overall, 5.7% (4/70) of the horses reacted to R. rickettsii antigens. Ticks were collected from 18.6% (13/70) of the horses and were identified as A. sculptum and Dermacentor nitens. Despite being a non-endemic area, seropositive animals were identified in our study, suggesting circulation of rickettsial agents in the region. This is the first serological survey of this agent in horses from the north-central region of Bahia, and further studies are needed to understand the epidemiology of BSF in these locations.

Análise de fatores predisponentes e ações de intervenção na febre maculosa brasileira em município endêmico

“…Entretanto, equinos já foram relatados em LPI em Divinópolis (Ramalho, 2017). Estes animais são frequentemente parasitados por A. sculptum e animais com sorologia positiva para R. rickettsii podem ser encontrados em áreas de interesse (Farias et al, 2021;Gazeta et al, 2009;Gerardi et al, 2019;Otomura et al, 2010;Ueno et al, 2016).…”

“…As ocorrências se concentram em áreas antropizadas do bioma mata Atlântica e nas áreas de transição entre esse bioma e o Cerrado. A presença de A. sculputm infectado por R. rickettsii e capivaras e/ou equinos nos locais prováveis de infecção (LPI), evidencia as características do cenário eco epidemiológico típico da FMB (Bitencourth et al, 2017;Farias et al, 2021;Rodrigues et al, 2017;Roux;Raoult, 2000;Souza et al, 2016). Apesar de seu impacto para a saúde coletiva, são incipientes os estudos sobre a FMB que avaliam conjuntamente aspectos relativos ao ambiente, incluindo vertebrados e carrapatos, aos seres humanos e às ações implementadas em nível de saúde pública (Barros-Silva et al, 2014;De Oliveira et al, 2016;Sousa et al, 2020).…”

Recent Advances in the Immunologic Method Applied to Tick-Borne Diseases in Brazil

“…Among the most prevalent TBDs, the only one that has a record for humans is Brazilian Spotted Fever (BSF), caused by R. rickettsii and R. parkeri strain Atlantic Forest [25,26]. According to Valente et al, there is a great diversity of ticks and hosts in Brazil, which reinforces the need for greater epidemiological monitoring of ticks in the country, mainly due to the increase in the number of reports of spotted fever [27].…”