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Published Date: 2012-08-24 23:42:34
Subject: PRO/AH/EDR> West Nile virus - USA (08)
Archive Number: 20120824.1262050

WEST NILE VIRUS - USA (08)
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Date: Wed 22 Aug 2012
Source: Press Briefing Transcript, CDC Telebriefing on West Nile Virus Update [edited]
http://www.cdc.gov/media/releases/2012/t0822_west_nile_update.html

[The following is part of a CDC press briefing transcript. The entire interview transcript is available at the above URL]

Today [22 Aug 2012] we're releasing new information about the number of people with a reported illness caused by West Nile virus. The updated information which is based on reports from state health departments was posted this morning on CDC's West Nile virus website. These data show that the number of West Nile virus disease cases in people has risen dramatically in recent weeks. And they indicate that we're in the midst of one of the largest West Nile virus outbreaks ever seen in the United States. People around the country are understandably very concerned about the outbreak; especially in hard-hit areas like Texas, where almost half of the cases have been reported. The Centers for Disease Control and Prevention (CDC) is working closely with state and local public departments to control the outbreak.

As of 21 Aug [2012], a total of 47 states have reported West Nile virus infections in people, birds or mosquitoes. The only states not reporting activity are Alaska, Hawaii, and Vermont. Of the 47 states that reported any West Nile virus activity, 38 had human cases of disease. A total of 1118 cases of West Nile virus disease in people, including 41 deaths, have been reported to the CDC. Of these, 629 or 56 per cent were classified as neuroinvasive disease, such as meningitis or encephalitis, and 489, or 44 per cent, were classified as non-neuroinvasive disease. These 1118 cases and 41 deaths identified thus far in 2012 are the highest numbers of West Nile virus disease cases reported to the CDC through the 3rd week in August since West Nile virus was 1st detected in the United States in 1999. In comparison, one month ago, there were only 25 people with West Nile virus disease reported to the CDC.

Approximately 75 per cent of the cases have been reported from 5 states, Texas, Mississippi, Louisiana, South Dakota and Oklahoma. About half are from Texas. The available information indicates that the numbers of reported cases are trending upward in most areas, including Texas. In addition, 242 potentially viremic blood donors were reported from 26 states. This compares with a total of 25 viremic blood donors reported just one month ago. All blood donors in the United States are screened for West Nile virus. By identifying these persons who could potentially spread West Nile virus through blood donations and deferring them from giving blood, we have taken an important step in preventing the spread of the virus and protecting the U.S. blood supply.

The peak of West Nile virus epidemics usually occur in mid-August; however, it takes a couple of weeks before people get sick, go to the doctor and get diagnosed and then are reported. Thus cases now being reported reflect infections from a week or more ago. Thus, we expect many more cases to occur and the risk of West Nile virus infection will probably continue through the end of September. Therefore, it's important for people to continue taking steps to protect themselves from mosquito bites.

We encourage the public to use insect repellents when they go outdoors, wear long sleeves and pants during dawn and dusk, install or repair screens on windows and doors, use air conditioning if you have it, empty standing water from items outside of your home such as gutters, flower pots, buckets, kiddie pools, and birdbaths. And support your local mosquito control program.

It's not clear why there's more West Nile virus activity in 2012 than in recent years. The weather, numbers of birds that maintain the virus, numbers of mosquitoes that spread the virus, and human behavior are all factors that can influence when and where outbreaks can occur. Also, the unusually mild winter, early spring, and hot summer in many parts of the country might have fostered conditions favorable to the spread of West Nile virus to people. It's difficult to predict how many more cases of West Nile virus disease we'll see this year. The CDC uses surveillance data from previous years to estimate trends of West Nile virus disease. But we don't have models to precisely predict the number of cases that will occur this season.

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Communicated by:
ProMED-mail from HealthMap Alerts
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[The high incidence of human West Nile virus (WNV) infections is indeed of concern, given that many weeks of the 2012 transmission season remain. One hopes that the public will heed the advice and take measures to avoid mosquito bites, reviving the "fight the bite" campaign of earlier years. - Mod.TY

A HealthMap/ProMED-mail map can be accessed at: http://healthmap.org/r/1hiS.]

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