Serological survey of Rickettsia sp. in horses and dogs in a non-endemic area in Brazil.

This research investigates the presence of the bacteria Rickettsia rickettsii, which causes lethal Brazilian Spotted Fever, in horses and dogs in a non-endemic area in Brazil. Despite the region having no history of Brazilian Spotted Fever, findings suggest vulnerability due to a lack of awareness and effective tick control measures.

Introduction and Background

• The study covers a research about Brazilian Spotted Fever (BSF), a lethal disease in humans instigated by the bacteria Rickettsia rickettsii. This disease is prevalent in certain Brazilian areas. Vital to the life cycle of this disease, horses and dogs can play the role of sentinel animals in epidemiological research.
• The research was carried out in Almirante Tamandaré, located in the State of Paraná, where no BSF case has been previously reported. The first human BSF case in the State of Paraná was noted in 2005.

Methodology

• Researchers gathered serum samples from diverse animals (71 horses and 20 dogs) across nine different property sites. Ticks, which are vectors of the bacteria causing BSF, were also collected from these animals for analysis.
• All farm owners completed a questionnaire aimed to measure their knowledge on BSF and methods they adopt for animal health management.
• Serum samples underwent analysis through the indirect immunofluorescent-antibody assay (IFA) using R. rickettsii and R. parkeri as antigens. In addition, ticks were subjected to Polymerase Chain Reaction (PCR) testing for the presence of Rickettsia sp.

Results

• The PCR results from the tick samples were negative for Rickettsia sp. Nevertheless, IFA results indicated that six horses (8.45%) and four dogs (20%) were seropositive for the bacteria.
• Interestingly, the questionnaire responses indicated that the farmers were generally not aware of any correlation between the existence of ticks and the risk of acquiring BSF.

Conclusion

• Even though the area of Almirante Tamandaré is officially non-endemic, evidence from this study suggests that it is a vulnerable environment for BSF, mainly due to the prevalence of seropositive animals and the lack of effective tick control measures.
• The findings underscore the urgent need for enhanced educational efforts to improve awareness among the farming community about the risks of ticks, and the implementation of effective tick control protocol to help prevent the emergence and spread of BSF in such non-endemic areas.