West Nile Virus and Other Domestic Nationally Notifiable Arboviral Diseases - United States, 2019.

Arthropod-borne viruses (arboviruses) are transmitted to humans primarily through the bites of infected mosquitoes and ticks. West Nile virus (WNV) is the leading cause of domestically acquired arboviral disease in the United States (1). Other arboviruses, including La Crosse, Jamestown Canyon, Powassan, eastern equine encephalitis, and St. Louis encephalitis viruses, cause sporadic disease and occasional outbreaks. This report summarizes surveillance data for nationally notifiable domestic arboviruses reported to CDC for 2019. For 2019, 47 states and the District of Columbia (DC) reported 1,173 cases of domestic arboviral disease, including 971 (83%) WNV disease cases. Among the WNV disease cases, 633 (65%) were classified as neuroinvasive disease, for a national incidence of 0.19 cases per 100,000 population, 53% lower than the median annual incidence during 2009-2018. More Powassan and eastern equine encephalitis virus disease cases were reported in 2019 than in any previous year. Health care providers should consider arboviral infections in patients with aseptic meningitis or encephalitis, perform recommended diagnostic testing, and promptly report cases to public health authorities. Because arboviral diseases continue to cause serious illness, and annual incidence of individual viruses continues to vary with sporadic outbreaks, maintaining surveillance is important in directing prevention activities. Prevention depends on community and household efforts to reduce vector populations and personal protective measures to prevent mosquito and tick bites such as use of Environmental Protection Agency-registered insect repellent and wearing protective clothing.*,†.