Five Emerging Neuroinvasive Arboviral Diseases: Cache Valley, Eastern Equine Encephalitis, Jamestown Canyon, Powassan, and Usutu

Christine M. Gill, MD; J. David Beckham, MD; Amanda L. Piquet, MD; Kenneth L. Tyler, MD; Daniel M. Pastula, MD, MHS


Semin Neurol. 2019;39(4):419-427. 

In This Article

Abstract and Introduction


There are many arthropod-borne viruses (arboviruses) capable of neuroinvasion, with West Nile virus being one of the most well known. In this review, we highlight five rarer emerging or reemerging arboviruses capable of neuroinvasion: Cache Valley, eastern equine encephalitis, Jamestown Canyon, Powassan, and Usutu viruses. Cache Valley and Jamestown Canyon viruses likely circulate throughout most of North America, while eastern equine encephalitis and Powassan viruses typically circulate in the eastern half. Usutu virus is not currently circulating in North America, but has the potential to be introduced in the future given similar climate, vectors, and host species to Europe (where it has been circulating). Health care providers should contact their state or local health departments with any questions regarding arboviral disease surveillance, diagnosis, treatment, or prevention. To prevent neuroinvasive arboviral diseases, use of insect repellent and other mosquito and tick bite prevention strategies are key.


Arboviruses, or arthropod-borne viruses, are mostly single-stranded ribonucleic acid (RNA) viruses that are transmitted through the bites of mosquitoes, ticks, or sandflies. Numerous arboviruses are capable of causing human disease ranging from a nonspecific systemic febrile illness to neuroinvasive disease (e.g., meningitis, encephalitis, and/or myelitis). Currently, West Nile virus is arguably the most well-known neuroinvasive arbovirus in North America. However, there are other arboviruses capable of neuroinvasion. In this review, we will highlight five rarer emerging or reemerging ones: Cache Valley, eastern equine encephalitis (EEE), Jamestown Canyon, Powassan, and Usutu viruses. While four are currently circulating within parts of North America (Cache Valley, EEE, Jamestown Canyon, and Powassan viruses), Usutu virus has the potential to be introduced into North America in the future given favorable climate, vectors, and host species. Increased awareness among clinicians (particularly neurologists) of such potential neuroinvasive arboviruses is crucial for optimizing surveillance and understanding the full clinical spectrum of disease they may cause.