Wild mammals as hosts of Rickettsia: a molecular evidence-based review

Rickettsia spp. are obligate intracellular bacteria that infect eukaryotic cells. These agents are transmitted primarily by hard ticks and other hematophagous arthropods, which are the vectors and primary reservoirs of several species. However, in the natural environment, Rickettsia spp. has been identified in wild and domestic mammals, as well as in ticks. This review comprehensively addresses the occurrence of rickettsiae in tissues of wild mammals on a global scale, considering different host groups across continents. Rickettsia DNA has been detected in bats, ungulates, carnivores, rodents and primates, thus underlining the broad spectrum of potential reservoirs. Extant evidence suggests that some may play role in endemic cycles of the bacteria. In Europe, a significant prevalence of Rickettsia DNA has been demonstrated in small rodents, indicating their potential as natural reservoir hosts. Research conducted in Asia and Africa has identified various Rickettsia species in rodents and insectivores, emphasizing their role in zoonotic transmission. The role of mammals as reservoirs of rickettsiae remains to be definitively established.