In 2021, there were 3,035 reports of arthropod-borne viruses (arboviruses) in the United States, including 2,911 caused by West Nile virus, according to research published in Morbidity and Mortality Weekly Report. Anna Fagre, DVM, PhD, and colleagues summarized 2021 surveillance data reported to the CDC by US jurisdictions for nationally notifiable arboviruses. e researchers identified the 3,035 reported cases of domestic arboviral disease in 49 states and the District of Columbia, including 2,911 caused by West Nile, 40 by La Crosse, 32 by Jamestown Canyon, 24 by Powassan, 17 by St. Louis encephalitis, six by an unspecified California serogroup, and five by eastern equine encephalitis viruses. Of the West Nile disease cases, 69% were classified as neuro invasive disease, for a national incidence of 0.61 cases per 100,000 population. “Healthcare providers should consider arboviral infections in the differential diagnosis of aseptic meningitis and encephalitis, obtain appropriate specimens for laboratory testing, and promptly report cases to public health authorities, particularly during the summer months when most infections occur,” Dr. Fagre and colleagues wrote.
