THURSDAY, Sept. 4, 2003 (HealthDayNews) -- The West Nile virus surged again across the western half of the United States last week, doubling its death toll and almost doubling the number of people infected by the mosquito-borne virus.
According to the latest U.S. government statistics reported Thursday, there have now been 43 deaths and 2,267 human infections in 35 states this year. Exactly a week ago, those tolls stood at 21 deaths and 1,442 cases of infection, which was double the numbers from the previous week.
Colorado remains the hardest-hit state, with 940 cases and 11 deaths, according to the latest figures on the Centers for Disease Control and Prevention Web site.
Nebraska now has 326 cases and has had eight fatalities. South Dakota has the third-highest number of cases, 250, but only three deaths. Texas and Wyoming round out the Top 5 list, with 164 cases each.
"Unlike last year, the virus activity this year is concentrated mainly in the western central U. S. instead of in the eastern central U.S.," says Dr. Roy Campbell, a medical epidemiologist with the CDC. For example, in 2002 Colorado had a total of 14 cases and no deaths. At this time last year, the total number of reported cases was 737 with no cases reported in Colorado, Campbell says.
Campbell expects the number of West Nile cases to increase over the next several weeks, since the epidemic does not peak until the end of September.
Another difference in this year's epidemic is that two-thirds of the cases are West Nile fever and one-third are encephalitis, which is a rapid inflammatory infection of the brain, Campbell says. This is the reverse of what was seen last year, he adds.
This difference, Campbell believes, is because more cases are being identified. In the past, cases of West Nile have been under-reported, he says.
Nobody knows why the virus has become less active in the eastern part of the country and more active in other parts, he adds.
"This year is looking a lot like 2002 in terms of the overall epidemic, but is different in the higher number of West Nile fever cases and in the areas most affected. The total number of cases will be around the same as 2002, when there were 4,156 cases, which was the largest epidemic mosquito-borne viral disease ever seen in North America," Campbell says.
The disease isn't limited to the United States. A Canadian Broadcasting Corporation report Thursday says officials have recalled all blood donated in Saskatchewan in August, citing an "epidemic" of West Nile in the province. Some 4,000 pints of blood are affected by the recall. They'll be replaced by donations from other regions of the country.
There are 97 confirmed and probable cases in Saskatchewan and another 33 under investigation, the CBC says.
For many people, the disease begins with flu-like symptoms. These can include abrupt headache, chills, fever, muscle aches, and light sensitivity. Some people infected with West Nile virus have no symptoms, but others develop fatal encephalitis.
Most people fully recover. However, the elderly, very young, and those with debilitating health conditions are at greatest risk for a severe or fatal episode.
To protect yourself from West Nile, the CDC advises avoiding mosquito bites. When going outside, you should apply an insect repellent that contains DEET. When possible, you should wear long sleeves and long pants and socks. The repellent should be sprayed on your clothes, not on your skin under your clothes, the CDC advises.
Dusk to dawn are the peak hours of mosquito activity, so try to avoid being outdoors, or if you must, use repellent and protective clothing in the early evening and early morning.
Be sure to drain any standing water around your house, as this is the ideal spot for mosquitoes to breed. And be sure open windows are screened.
The CDC also asks that you report any dead birds to your local health department. More than 110 species of birds are known to carry the virus. West Nile spreads from infected birds bitten by mosquitoes to humans and other animals the mosquitoes bite.
More information
To learn more about the West Nile virus, visit the CDC or the Food and Drug Administration.
