Bats and zoonotic viruses: can we confidently link bats with emerging deadly viruses?

Abstract

An increasingly asked question is 'can we confidently link bats with emerging viruses?'. No, or not yet, is the qualified answer based on the evidence available. Although more than 200 viruses - some of them deadly zoonotic viruses - have been isolated from or otherwise detected in bats, the supposed connections between bats, bat viruses and human diseases have been raised more on speculation than on evidence supporting their direct or indirect roles in the epidemiology of diseases (except for rabies). However, we are convinced that the evidence points in that direction and that at some point it will be proved that bats are competent hosts for at least a few zoonotic viruses. In this review, we cover aspects of bat biology, ecology and evolution that might be relevant in medical investigations and we provide a historical synthesis of some disease outbreaks causally linked to bats. We provide evolutionary-based hypotheses to tentatively explain the viral transmission route through mammalian intermediate hosts and to explain the geographic concentration of most outbreaks, but both are no more than speculations that still require formal assessment.

Fig. 1A:. Seba's short-tailed bats [Carollia perspicillata (Phyllostomidae)]; B: greater spear-nosed bats [Phyllostomus hastatus (Phyllostomidae)] using human-made constructions as day roosts; C: flying-foxes (Pteropidae) hanging on trees during the day; D: lesser dog-like bats [Peropteryx macrotis (Emballonuridae)] roosting in the crevice of a rock in the edge of a river (the inset shows the entrance to the crevice). A and B are courtesy of A Pol (Federal Rural University of Rio de Janeiro, Brazil), C was acquired from Shutterstock Inc and D is courtesy of E Rubião (self-employed contractor). Photographers are the copyright holders of the images.

Fig. 2A-F:. New World leaf-nosed bats of family Phyllostomidae, including frugivores - the great-eating fruit bat (Artibeus lituratus) (A) with seeds in the fur and the little yellow-shouldered bat (Sturnira lilium) (B), insect eaters - the common big-eared bat (Micronycteris cf. microtis) (C) and the stripe-headed round-eared bat (Tonatia saurophila) (D), a blood feeder - the white-winged vampire bat (Diaemus youngi) (E) and a nectar feeder - the Thomas's nectar bat (Hsunycteris thomasi) (F); G-I: Old World fruit bats of family Pteropodidae, including the black flying-fox (Pteropus alecto) (G), the spectacle flying-fox (Pteropus conspicillatus) (H) and the hammer-headed fruit bat (Hypsignathus monstrosus) (I). A and B are courtesy of RLM Novaes (Oswaldo Cruz Foundation, Brazil), C-F are courtesy of A Pol (Federal Rural University of Rio de Janeiro, Brazil), G and H are courtesy of A Breed (Animal and Plant Health Agency, Addlestone, Surrey, United Kingdom) and I is courtesy of Jakob Fahr (Max Planck Institute for Ornithology, Germany). Photographers are the copyright holders of the images

Fig. 3:. sugar plum (Uapaka kirkiana; Phyllanthaceae) with bat tooth marks on fruits husks, Zambia. Courtesy of Jakob Fahr (Max Planck Institute for Ornithology, Germany), the copyright holder of the image.