Expanded host diversity and global distribution of hantaviruses: Implications for identifying and investigating previously unrecognized hantaviral diseases

A once-exotic group of rodent-borne viruses, belonging to the Hantavirus genus of the Bunyaviridae family, gained widespread attention within the medical community and general public during an outbreak of a mysterious and lethal respiratory disease occurring among healthy young adults in the southwestern USA in 1993. The causative agent was identified as a hantavirus hosted by the North American deer mouse (Peromyscus maniculatus). Rodents (order Rodentia, families Muridae and Cricetidae) have long been known to harbor hantaviruses, and new hantaviruses continue to be found in rodents of multiple species in Europe, Asia, and the Americas. By contrast, hantaviruses have just recently been detected in Africa, notably Sangassou virus in the African wood mouse (Hylomyscus simus) and Tigray virus in the Ethiopian white-footed mouse (Stenocephalemys albipes). In addition to rodents, genetically distinct hantaviruses have been identified in shrews and moles (order Eulipotyphla, families Soricidae and Talpidae) and insectivorous bats (order Chiroptera) of numerous species from widely separated geographic regions. Phylogenetic analyses, based on partial and full-length genomes of rodent- and non-rodent-borne hantaviruses, lend support to the concept that ancestral shrews, moles, and/or bats may have predated rodents as the reservoir hosts of primordial hantaviruses. Thus, the rapidly changing global landscape of hantaviruses is that of a genetically diverse virus group distributed across hosts of evolutionarily diverse taxonomic orders and ecological niches, with largely unknown biology, evolution, phylogeography, and pathogenicity. As with other still-orphan viruses, identifying and investigating diseases caused by one or more of these newfound hantaviruses pose myriad challenges, but findings from such studies may better prepare the next generation of health-care providers to respond more rapidly to future outbreaks of previously unrecognized hantaviral diseases.