Common Themes in Zoonotic Spillover and Disease Emergence: Lessons Learned from Bat- and Rodent-Borne RNA Viruses

Abstract

Rodents (order Rodentia), followed by bats (order Chiroptera), comprise the largest percentage of living mammals on earth. Thus, it is not surprising that these two orders account for many of the reservoirs of the zoonotic RNA viruses discovered to date. The spillover of these viruses from wildlife to human do not typically result in pandemics but rather geographically confined outbreaks of human infection and disease. While limited geographically, these viruses cause thousands of cases of human disease each year. In this review, we focus on three questions regarding zoonotic viruses that originate in bats and rodents. First, what biological strategies have evolved that allow RNA viruses to reside in bats and rodents? Second, what are the environmental and ecological causes that drive viral spillover? Third, how does virus spillover occur from bats and rodents to humans?

Keywords: RNA viruses; bats; outbreak; reservoir; rodents; spillover; zoonosis.

Figure 1

Major routes of spillover transmission of viruses harbored by bats and rodents. Three of the most common routes of exposure from bats or rodents to humans are depicted. As illustrated, more than one route may occur. Abbreviations: RABV, rabies viruses; HeV, Hendra henipavirus; NiV, Nipah hendravirus; MARV, Marburg marburgvirus; SARS-CoV, severe acute respiratory syndrome coronavirus; EBOV, Ebolavirus species.