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West Nile Virus Alert

This is a year for mosquitoes and the spread of the mosquito-borne West Nile virus around the country, federal officials say.

So, people must take steps to fight the bite and prevent infection says Dr. Julie Gerberding, the Director at Centers for Disease Control and Prevention (CDC). On The Early Show, Gerberding says blood screening efforts, vaccine research and a new test for West Nile are all helping in efforts to combat the virus.

The 2003 West Nile season is already under way, with 32 states reporting virus-infected mosquitos, birds and animals. Four human cases of the West Nile infection have been reported so far — three in Texas and one in South Carolina. A fifth case is under investigation in a third state. That's exactly the number of human cases as a year ago, but 12 more states are reporting it at this point as compared to the same time last year.

Gerberding says West Nile activity has increased, and an upswing of activity is expected toward the end of July and August. And, this year the virus may emerge on the west coast for the first time.

There have also been cases of even more rare mosquito-borne diseases this year: St. Louis encephalitis and two cases of eastern equine encephalitis (EEE). Gerberding says when testing for West Nile, it is important to distinguish between West Nile, St. Louis and EEE cases. He says as surveillance and testing get better, it is likely that the numbers of cases reported will go up for all three diseases.

Avoiding exposure to these viruses is still the best prevention. Health officials advise people to be prepared and take steps to protect themselves.

For the summer, Gerberding suggests:

  • Use insect repellent.
  • Get rid of standing water in flowerpot drip pans, unused swimming pools, rain barrels or children's toys that mosquitoes use to breed.
  • Avoid going out at dusk and dawn when mosquito activity is high.
  • Wear long sleeves and pants or an insect repellent with a concentration of about 30 percent DEET for adults and about 10 percent for children.

Gerberding says research is improving diagnosis, prevention and the development of vaccines and therapies for West Nile. Basic research funding has resulted in a hamster model for testing West Nile interventions, he says.

There are also efforts to code the yellow fever vaccine for West Nile proteins. It is a "chimeric virus" approach, which has been tested in primates effectively and safely, according to Gerberding. Early human trials of the vaccine may begin this summer. Gerberding says the approach may be the best weapon against the virus. Other vaccine developments are further away. Animal testing is also underway with various potential drug therapies. Immune globulin therapy studies may begin in humans soon.

West Nile virus was initially recognized in the United States in 1999 in New York, and has spread further throughout the country each subsequent year. About 80 percent of people who are infected with West Nile shows no symptoms and suffer no problems. The other 20 percent develops symptoms including fever, headache, body aches, tremors and skin rashes. Fewer than 1 percent of those infected develop life-threatening medical conditions such as meningitis or brain inflammation. Some patients are at increased risk of more severe illness, including immunocompromised patients, people over the age of 65 or women who are pregnant. Currently, there is no treatment for the virus.

Last year, more than 4,000 people in this country were sickened by West Nile and there were 284 deaths in 39 states and the District of Columbia. There were also 23 cases nationwide, in which West Nile was passed on through a blood transfusion. There were four cases, in which organ recipients contracted the virus.

American blood banks began testing donated blood for West Nile this month. In Texas, the new test found the virus in blood donated by a 46-year-old woman who had no symptoms of West Nile. There are other suspected cases of the disease being investigated.

Besides the screening test for the disease, blood banks are asking people who donate to contact the donor agency if they later come down with symptoms of West Nile so the blood can be removed from the supply.

The FDA approved a new test for West Nile this year that can diagnose the disease in people more quickly than existing tests. The new test gives results within a day as opposed to two or three weeks.