WEDNESDAY, Sept. 5 (HealthDay News) -- One of the worst outbreaks of West Nile virus ever to strike the United States has yet to subside, federal health officials said Wednesday, with a new total of 1,993 cases involving people, including 87 deaths.
While all states except Alaska and Hawaii have reported at least one case of West Nile virus, more than 70 percent of cases have come from six states -- Texas, South Dakota, Mississippi, Oklahoma, Louisiana and Michigan.
The outbreak has hit hardest in Texas, where nearly half (45 percent) of the total U.S. cases have been reported.
"The 1,993 cases reported thus far in 2012 is the highest number of West Nile disease cases reported to CDC through the first week in September since West Nile virus was first detected in the United States in 1999," Dr. Lyle Petersen, director of CDC's Division of Vector-Borne Infectious Diseases, said during a noon press conference.
As of Tuesday, 1,069 cases (54 percent) were classified as neuroinvasive disease -- when the virus enters the nervous system causing conditions such as meningitis or encephalitis. The remaining 924 cases (46 percent) were classified as non-neuroinvasive disease, the CDC said.
Petersen said the epidemic probably peaked in mid to late August. And though "we may be past the historical peak, we expect that a great many cases of West Nile virus disease have not yet been reported, largely because of a lag when a person gets sick and the disease is reported," he said.
The reasons for the outbreak this year aren't clear. A drought in Texas may have played a role, but there are probably other factors as well, officials said.
The best way to avoid the virus is to wear insect repellant and support local programs to eradicate mosquitoes, Petersen said.
There is currently no treatment for West Nile virus and no vaccine to prevent it, he added.
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