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West Nile virus cases in 2012 reached 9-year high
In 2012, CDC received 5,780 reports of nationally notifiable arboviral disease cases, 98% of which were West Nile virus after a multistate outbreak, the most since 2003, according to a recent report in the Morbidity and Mortality Weekly Report.
“Arboviruses continue to cause serious illness in substantial numbers of persons in the United States,” researchers wrote. “Maintaining surveillance remains important to identify outbreaks and guide prevention efforts.”
Other nationally notifiable arboviral diseases in 2012 included: Eastern equine encephalitis virus, Powassan virus, St. Louis encephalitis virus, La Crosse virus, Jamestown Canyon virus, and an unspecified California serogroup virus.
The 5,674 West Nile virus disease cases were reported from 976 counties in 48 states, the District of Columbia and Puerto Rico. Overall, 62% of those infected were hospitalized and 5% died. Fifty-one percent of the cases were reported as neuroinvasive. Of those, 56% had encephalitis, 36% meningitis, and 8% acute flaccid paralysis. Of those with acute flaccid paralysis, 83% also had encephalitis or meningitis.
La Crosse virus (78 cases) was reported from 50 counties in 11 states, 91% of which were neuroinvasive. Eastern equine encephalitis nueroinvasive cases (15 cases) were reported from six states, 93% of those were hospitalized and 33% died. Powassan virus (seven cases) was reported from three states, 86% of those infected were hospitalized and none died. St. Louis encephalitis virus (three cases) was reported from Texas; only one of those infected was hospitalized and no deaths were reported.
“Health care providers should consider arboviral infections in the differential diagnosis of cases of aseptic meningitis and encephalitis, obtain appropriate specimens for laboratory testing and promptly report cases to public health authorities,” researchers wrote.
Disclosure: The researchers report no relevant financial disclosures.
