Dr. Lyle Petersen, director of the division of vector-borne infectious diseases at the Centers for Disease Control and Prevention in Atlanta, said a total of 48 states have reported West Nile virus infections in people, birds or mosquitoes with only Alaska and Hawaii reporting no West Nile virus activity.
The CDC received reports of 1,590 cases of West Nile virus disease in people, including 66 deaths, and of these, 56 percent were classified as neuroinvasive disease, such as meningitis or encephalitis; and 44 percent were classified as non-neuroinvasive disease.
Human case reporting is a lagging indicator, because it takes time for somebody to get infected, develop symptoms and then go to the doctor to get diagnosed and have it reported. Even if West Nile transmission stopped tomorrow, many cases would continue to be reported in the coming weeks and even months, Petersen said.
More than 70 percent of the cases have been reported from six states, which in descending order are: Texas, South Dakota, Mississippi, Oklahoma, Louisiana, and Michigan -- nearly half of the cases were in Texas, Petersen said.
"Previous experience has shown that floods and hurricanes do not typically result in increased transmission of West Nile virus," Petersen said in a telephone news conference. "Nevertheless, small increases in the numbers of West Nile cases were noted in some areas of Louisiana after Hurricane Katrina."