Investigators Survey Rickettsia Antibodies and Tick Carriers

The results of a study inPLoS Neglected Tropical Diseasesdetail how investigators at the Federal University of Parana surveyed the prevalence ofRickettsiaantibodies andRickettsia-carrying ticks in human hunters, hunting dogs, and wild boars in Brazil in an effort to study theRickettsiabacteria's circulation and ecology among human populations and wild animals in that country.

The investigators collected blood samples and ticks from 80 free-range wild boars, 34 hunters, and 170 hunting dogs from central-western and southern Brazil between 2016 and 2018. Blood samples were then tested for the presence of anti-Rickettsiaantibodies. Tick species were identified, and a subset of ticks were tested for bacteria in the spotted fever groupRickettsia.

A total of 1584Amblyommaticks of 3 species were collected from wild boars, whereas all 22 ticks on hunters were of the speciesAmblyomma sculptum, and the 9 ticks on hunting dogs were all of theAmblyomma aureolatumspecies. About 14.7% of hutners, 14.1% of hunting dogs, and 72.5% of wild boars were positive forRickettsiaantibodies. Additionally, 164 ticks were tested for spotted fever groupRickettsia,but none were positive. Differences betweenRickettsiarates in central-western versus southern Brazil were not statistically significant in this study.

Most infections caused byRickettsiabacteria are spread through fleas, lice, mites, or ticks. Symptoms of infection withRickettsiaparkeri, called Pacific Coast tick fever, include fever, headache, muscle aches, and rash.

Rickettsia rickettsii, the main pathogen causing spotted fever in Brazil, is transmitted to humans byAmblyommaticks, according to the study results.

Few details have been available on the occurrence of ticks andRickettsiain wild boar populations or how many boars may spread the bacteria to human populations.

Reference

Kmetiuk LB, Krawczak FS, Machado FP, et al. Ticks and serosurvey of anti-Rickettsia spp. antibodies in wild boars (Sus scrofa), hunting dogs and hunters of Brazil.PLoS Negl Trop Dis.2019;13(5):e0007405. doi: 10.1371/journal.pntd.0007405.