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

The research article discusses the detection of antibodies against Rickettsia rickettsii, a bacteria causing Brazilian spotted fever, in horses from a non-endemic area in Bahia, Brazil, suggesting potential circulation of these bacterial agents in the region.

Objective and Methodology

• The aim of this study was to investigate the presence of Rickettsia rickettsii in horses from a non-endemic region in Bahia, Brazil. Horses are believed to be efficient sentinels for the circulation of Rickettsia bacteria as they are the primary hosts for the main vector of this bacteria, Amblyomma sculptum.
• The researchers collected blood samples and ticks from 70 horses across four municipalities in the Bahia region. They analyzed the serum from these samples using an indirect immunofluorescence assay to detect the presence of anti-Rickettsia antibodies.

Findings

• The results showed that 5.7% (4 out of 70) of the horses tested had antibodies reactive to R. rickettsii antigens, indicating previous exposure to this bacteria.
• In addition, ticks were collected from about 18.6% of the horses and identified as Amblyomma sculptum and Dermacentor nitens, both of which can act as vectors or carriers for Rickettsia bacteria.

Implications

• The detection of antibodies and ticks that can carry Rickettsia in horses from a non-endemic area suggests potential circulation of these bacterial agents in the region.
• This is the first study to detect the presence of R. rickettsii in horses from the north-central region of Bahia, paving the way for further research to better understand the epidemiology of Brazilian spotted fever in these non-endemic regions.