ATLANTA (AP) -- U.S. health officials reported Wednesday three times the usual number of West Nile cases for this time of year and one expert called it "one of the largest" outbreaks since the virus appeared in this country in 1999.
So far, 1,118 illnesses have been reported, about half of them in Texas, according to the Centers for Disease Control and Prevention. In an average year, fewer than 300 cases are reported by mid-August. There have also been 41 deaths this year.
"We're in the midst of one of the largest West Nile outbreaks ever seen in the United States," said Dr. Lyle Petersen, a CDC official.
Never before have so many illnesses been reported this early, said Petersen, who oversees the CDC's mosquito-borne illness programs.
Most infections are usually reported in August and September, so it's too early to say how bad this year will end up, CDC officials said.
They think the mild winter, early spring and very hot summer have fostered breeding of mosquitoes that pick up the virus from birds they bite and then spread it to people.
As of Aug. 21, the CDC had confirmed reports of West Nile virus in 47 states. In Arizona, the CDC reports seven neuorinvasives cases of the disease, five non-neuroinvesive cases and one fatality.
West Nile virus was first reported in the U.S. in 1999 in New York, and gradually spread across the country over the years. It peaked in 2002 and 2003, when severe illnesses reached nearly 3,000 and deaths surpassed 260. Last year was mild with fewer than 700 cases.
Only about one in five infected people get sick. One in 150 infected people will develop severe symptoms including neck stiffness, disorientation, coma and paralysis.
In recent years, cases have been scattered across the country. Hot spots are usually in southeast Louisiana, central and southern California, and areas around Dallas, Houston, Chicago and Phoenix.
Those areas seem to have a combination of factors that include the right kinds of virus-carrying mosquitoes and birds, along with large numbers of people who can be infected, health officials say.
The best way to prevent West Nile disease is to avoid mosquito bites. Insect repellents, screens on doors and windows and wearing long sleeves and pants are some of the recommended strategies. Also, empty standing water from buckets, kiddie pools and other places to discourage breeding.
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.