ATLANTA -- West Nile virus cases in the United States rose more than 16 percent this year, with a marked increase along the hurricane-ravaged Gulf Coast, the government reported yesterday.
Health officials had worried that standing water left by hurricanes Katrina and Rita would allow mosquito populations to explode and the virus to proliferate.
The number of human cases in Louisiana, Mississippi, Alabama, and Texas increased by about 24 percent from 2004, the Centers for Disease Control and Prevention said.
But health officials were most concerned about West Nile cases that resulted in serious neurological diseases such as encephalitis and meningitis. And the number of those along the Gulf Coast rose only 17 percent, compared with 27 percent nationally.
A large-scale evacuation, aggressive pesticide spraying, and other post-hurricane efforts may have played a role, said Lora Davis, a CDC epidemiologist.
West Nile virus is most commonly spread to humans by mosquitoes. It was first reported in the United States in New York in 1999 and has spread steadily westward since then. Most infected people never get sick, but about 20 percent suffer symptoms resembling the flu. Fewer than 1 percent become severely ill, some with potentially fatal inflammation of the brain or spinal cord.
A total of 2,744 cases in humans were reported from Jan. 1 to Dec. 1, up from 2,359 reported in the same period of 2004, according to the CDC.
So far this year, 1,365 people have been hospitalized with meningitis, encephalitis, fever, or other illnesses caused by West Nile. There have been 98 deaths. Most of the cases occurred in the summer, when mosquitoes are most active. For the same period last year, 1,027 were hospitalized and 83 died.
In the four Gulf Coast states, the total number of cases went from 287 in the first 11 months of 2004 to 376 during the same period this year. Those numbers include neurological cases, which went from 212 to 256.