(AP) -- West Nile virus cases are up 40 percent since last week and may rival the record years of 2002 and 2003, federal health officials said Wednesday.
So far this year, 1,590 cases of the mosquito-borne disease have been reported to the Centers for Disease Control and Prevention, and 66 deaths. Nearly half of the total cases and most of the deaths are in Texas. Arizona is faring much better than The Lone Star State, with 16 cases and one death reported.
About half of the cases are serious illnesses, and the CDC considers those the best indicator of West Nile activity because many mild cases do not get reported and their symptoms may not even be recognized.
Typical symptoms are fever, headache and body aches, and most people get better on their own in a few days. Less than 1 percent develops neurological symptoms such as stiff necks and even coma and paralysis.
Based on reports of West Nile so far this year, "we think the numbers may come close" to those of 2002 and 2003, when nearly 3,000 severe illnesses and more than 260 deaths occurred each year, said the CDC's top expert on the disease, Dr. Lyle Petersen.
Health officials think that West Nile activity will peak in mid-to-late August, but likely will continue through October. Because symptoms can take two weeks to appear, reporting cases lags behind when people became infected.
The disease first appeared in the United States in 1999. Officials say this year's early spring and hot summer may have contributed to the current boom in cases. Mosquitoes get the virus from feeding on infected birds and then spread the virus to people they bite.
All states except Alaska and Hawaii have found West Nile virus in people, birds or mosquitoes this year. Texas has been the hardest hit, accounting for half of the cases reported to the CDC so far.
"I'm not convinced that we have peaked. We may have plateaued," said Dr. David Lakey, commissioner of the Texas Department of State Health Services.
The CDC also says it does not expect Hurricane Isaac to have much of an impact on cases in Southern states. Heavy storms can wash out mosquito breeding grounds, although standing water can aid breeding, Petersen said. Many other factors, such as the population of infected birds, influence the severity of West Nile outbreaks, he said.
Since turning up in Arizona in 2003, there have been more than 1,000 confirmed cases reported. The 2011 season was mild with just 45 reported cases.
Maricopa County's worst season on record occurred in 2004. There were 355 confirmed cases of West Nile virus that year. The second-worst season -- 115 cases -- was two years ago in 2010.
“We are seeing a lot of positive mosquito pools and with the continued monsoon, we recognize that the risk for WNV infection will likely continue into the fall,” said John Kolman, director of Maricopa County Environmental Services Department, in a recent news release.
With that in mind, county health officials have developed a campaign they call "Fight the Bite," offering simple precautions people should take to avoid mosquitoes and prevent infestations.
- Avoid outside activity between dusk and dawn, when mosquitoes are most active.
- Wear lightweight clothing that covers your arms and legs and use an insect repellent if you must be outdoors when mosquitoes are active. Always follow the directions on the label.
- Make sure doors and windows have tight fitting screens and remain closed.
- Eliminate mosquito-breeding sites around the home by removing standing water in potted plants, tires, bird baths and other containers where water may collect.
- Ensure that swimming pools and decorative water features are properly maintained.
- Change water in flowerpots, birdbaths and pet watering bowls located outdoors at least twice per week.
For more information on West Nile virus, public health assistance, to report green pools or file any mosquito-related complaint, call the West Nile Virus General Information and Help 602-506-0700 or visit www.maricopa.gov/wnv.