Non-human primates as a reservoir for rabies virus in Brazil.

Rabies virus (RABV) does not persist in the environment as it is a very fragile agent. The primary hosts are mammalian species in the orders Carnivora and Chiroptera. Since the late 1980s, RABV has been isolated from non-human primates, Callithrix jacchus (the white-tufted marmoset), in four coastal states (Rio Grande do Norte, Ceará, Piauí and Pernambuco) in north-eastern Brazil, where this species is indigenous. The original habitat of C. jacchus consisted of two Brazilian biomes, the Atlantic Forest and the Caatinga. However, these marmosets have since adapted to other ecosystems as a result of human activities. Between 1988 and 1989, RABV isolates were obtained from white-tufted marmosets in the state of Rio Grande do Norte, but antigenic and genetic identification studies were not conducted at that time. In the following years, three additional states reported cases (Ceará, Piauí and Pernambuco). In two of these states (Ceará and Piauí), human cases of rabies transmitted by marmosets were reported. According to Brazilian Health Ministry data, at least 19 human cases in which this species was the source of infection were registered in between 1990 and 2016. Recent findings in laboratory tests of 12 rabid samples from humans and marmosets and the regional transmission among these animals for over 20 years, together with the gradual increase in the affected geographic area, support the concept of the emergence of a new RABV reservoir. Regional tourism, the wild animal trade and the cultural practice of maintaining these animals as pets, particularly in coastal regions, appear to be major risk factors for the increase in human cases. Additional epidemiological and ecological studies are required to better understand local disease dynamics and to identify ideal opportunities for prevention and control of this fatal infection.