Epidemiological factors associated with the spatial distribution of two Rickettsia hosts in a locality of Yucatán, Mexico

Abstract

Rickettsioses caused by the spotted fever group (SFG) and typhus group (TG) are endemic in southeastern Mexico. Dogs and rodents can host several species of these bacteria, but little is known about the epidemiological factors that influence the infection risk in these mammals. This study aims to identify the frequency of Rickettsia SFG and TG infection in the studied animals, to determine the spatial distribution of the hosts, and to identify the factors associated with the infection risk. Genomic DNA was obtained from 66 dog blood samples and 36 rodent spleens collected in 48 dwellings from the rural locality of Ucú, Yucatan, Mexico. Rickettsia SFG or TG infection was determined using a multiplex semi-nested PCR (snPCR). The predictor variables for the infection risk in dogs and rodents were selected using generalized linear models (GLM) (p < 0.05). snPCR revealed Rickettsia DNA in 28.1% (18/64, 95% CI 17.6%-40.8%) of dogs and 27.8% (10/36, 95% CI 14.2%-45.2%) rodents. Only Rickettsia SFG was detected in dogs, while rodents hosted both Rickettsia TG and SFG. According to the corresponding GLM, dogs living in the interior area of Ucú have a lower risk of infection by Rickettsia SFG (RR = 0.14) than those living in the other areas. The presence of opossums (Didelphis sp.) in the dwelling increases the risk of Rickettsia TG infection in rodents (RR = 14), and the presence of SFG-infected dogs in the dwelling increases the risk of Rickettsia SFG infection in rodents (RR = 21).