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.
Dr. David Lakey, commissioner of the Texas Department of State Health Services, said health officials in his state "continue to be very concerned about the West Nile outbreak we are seeing."
"Historically, August is the peak but this year has been unpredictable, the virus has been unpredictable, and we have a large number of cases," he said, adding "2012 is now officially our worst year for West Nile."
Generally speaking, 80 percent of people who are infected with West Nile virus develop no or few symptoms, while 20 percent develop mild symptoms such as headache, joint pain, fever, skin rash and swollen lymph glands, according to the CDC.
People older than 50 and those with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease and organ transplants, are at greater risk for serious illness.
There are no specific treatments for West Nile virus.
Although most people with mild cases of West Nile virus will recover on their own, the CDC recommends that anyone who develops symptoms should see their doctor right away. The best way to protect yourself from West Nile virus is to avoid getting bitten by mosquitoes, which can pick up the disease from infected birds. The CDC recommends the following steps to protect yourself:
For more on West Nile virus, visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Sept. 5, 2012, press conference with Lyle R. Petersen, M.D., M.P.H., director, Division of Vector-Borne Infectious Diseases, U.S. Centers for Disease Control and Prevention; David L. Lakey, M.D., Commissioner, Texas Department of State Health Services
All rights reserved