Serologic and molecular survey for Rickettsia in small mammals in the Andes of Colombia

Zoonotic vector-borne infectious diseases represent a significant global challenge. Ticks are one of the most important vectors globally, transmitting a wide range of pathogens. Among these pathogens, bacteria of the genus Rickettsia cause zoonotic diseases, knows as rickettsioses, that primarily affect tropical and subtropical regions. Rickettsiae are transmitted between vertebrate hosts and vectors, with some wild mammals serving as key amplifying hosts. In Colombia, the limited information on wild reservoirs contrasts with their high diversity, which includes 553 native mammal species, and 51 species of ticks associated with wild mammal hosts. To detect Rickettsia exposure and infections in wild mammals from the Colombian Andean region, serum, blood, and organ samples were collected from wild mammals in the Departments of Caldas and Risaralda, Colombia, between July 2021 and November 2022. A total of 147 mammals belonging to 58 species and three orders (Didelphimorphia, Chiroptera, and Rodentia) were captured. The indirect immunofluorescence assays analysis detected antibodies for Rickettsia in 100 % of didelphids, 65.2 % of rodents, and 45.9 % of bats. Rickettsia DNA was detected in 4.1 % of the mammals analyzed, with 'Candidatus Rickettsia andeanae', Rickettsia felis, Rickettsia rickettsii, and Rickettsia parkeri identified in rodents and bats. The detection of Rickettsia in wild mammals reinforces their role as reservoirs and highlights the need to investigate their ecology to improve surveillance and control of rickettsiosis in Colombia.