# 6659
While the peak in transmission of the West Nile Virus probably occurred more than a month ago, cases – and fatality reports – continue to come in at a near-record pace.
This is not entirely unexpected, given the incubation time for the virus (2-15 days), delays in processing local and state reports, and the reality that some patients may succumb after weeks or even months of treatment.
Today’s update from the CDC’s DVBID summarizes the latest numbers below:
2012 West Nile virus update: October 23
As of October 23, 2012, 48 states have reported West Nile virus infections in people, birds, or mosquitoes. A total of 4,725 cases of West Nile virus disease in people, including 219 deaths, have been reported to CDC. Of these, 2,413 (51%) were classified as neuroinvasive disease (such as meningitis or encephalitis) and 2,312 (49%) were classified as non-neuroinvasive disease.
The 4,725 cases reported thus far in 2012 is the highest number of West Nile virus disease cases reported to CDC through the fourth week in October since 2003. Almost 70 percent of the cases have been reported from eight states (Texas, California, Louisiana, Mississippi, Illinois, South Dakota, Michigan, and Oklahoma) and over a third of all cases have been reported from Texas.
The 20% increase in deaths – up from 183 last week, to 219 this week - is indicative of fatality reports being a lagging indicator.
In contrast, the number of new neuroinvasive cases rose only by 120, or about 5%. Perhaps a sign that the number of new cases is beginning to decline.
Neuroinvasive cases (which present with meningitis, encephalitis, or flaccid Paralysis) are severe enough that they result in hospitalization and diagnosis, and so they are considered the best indicator of the scope of each year’s epidemic.
Mild cases – called West Nile Fever – often go undiagnosed, with probably only 2%-3% being identified.
The states hardest hit by the neuroinvasive illness continue to center around the middle of the country, with Texas accounting for roughly 1/3rd of all of the serious WNV infections (n=742) in the nation.
Even though cooler fall weather has reduced mosquito activity across much of the country - with no vaccine, and the virus now endemic across much of the country - health departments continue to urge people to follow the `5 D’s’ of protection anytime mosquitoes may be active:
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