Epidemiological aspects of the Brazilian spotted fever: serological survey of dogs and horses in an endemic area in the State of São Paulo, Brazil.

This research focused on studying the presence of Brazilian spotted fever in domestic animals specifically dogs and horses in the State of São Paulo, Brazil, a declared endemic area. Antibody tests were conducted to identify any infection from rickettsiae, microorganisms associated with the fever. Animals from both endemic and non-endemic areas were surveyed, with a higher positive rate in the former.

Methodology and Results

• The researchers conducted the study in the County of Pedreira, State of São Paulo, Brazil which had previously reported 17 human cases of Brazilian spotted fever.
• Serum samples from dogs and horses were taken and tested for detectable antibodies to rickettsiae, the microorganisms responsible for spotted fever. The indirect immunofluorescence technique was used for testing.
• Out of 33 dogs from the endemic area, 12 (36.4%) tested positive for the antibodies. Among the nine horses tested in the same area, seven (77.8%) were seropositive.
• The researchers also tested animals from non-endemic areas for comparison. Out of 31 dogs, four (12.9%) were seropositive and similarly, three (27.3%) out of 11 horses tested positive.
• The highest titers of antibodies (IgG > or = 1:1024) were found only in three dogs and six horses from the endemic area.

Conclusions and Implications

• The study found a higher incidence of antibodies to spotted fever-group rickettsiae in dogs and horses in the endemic area as compared to the non-endemic area.
• This suggests that the dogs and horses may be acting as environmental sentinels, helping in establishing the prevalence and spread of the fever in Brazil.
• Understanding the population and the spread of this disease across regions can aid in devising effective prevention and containment strategies.