The current West Nile outbreak is one of the largest in the U.S., with four times the usual number of cases for this time of year, federal health officials said Wednesday.

It's still too early to say how bad the year will end up because most infections are reported in August and September. But never before have so many illnesses been reported this early, said Dr. Lyle Petersen, of the Centers for Disease Control and Prevention.

“We're in the midst of one of the largest West Nile outbreaks ever seen in the United States,” said Petersen, who oversees the CDC's mosquito-borne illness programs.

So far, 1,118 illnesses have been reported, about half of them in Texas. In an average year, fewer than 300 cases are reported by mid-August. There have also been 41 deaths this year, the CDC said.

And cases seem to be accelerating: about 400 of the cases were reported in just the last week.

Experts think the mild winter, early spring and very hot summer helped stimulate mosquito breeding and the spread of the virus. Mosquitoes pick up the virus from birds they bite and then pass it on to people.

CDC officials are also looking into the possibility that the virus mutated, but so far have no information showing that happened, Petersen said.

West Nile virus was first diagnosed in Uganda in 1937, but no cases were reported in the U.S. until 1999 in New York. The virus gradually spread across the country.

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 1 in 5 infected people get sick. Early symptoms can include fever, headache and body aches. Some recover in a matter of days. But 1 in 150 infected people will develop severe symptoms including neck stiffness, disorientation, coma and paralysis.

Many illnesses probably go unreported, especially milder cases. In this year's case count, more than half are severe, CDC officials said.

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.

Illnesses this year have been reported in 38 states, but the bulk of them have been in Texas, with a concentration in the Dallas area.

It's not clear why Texas is seeing so many cases, but it's alarming. Twenty-one deaths have been reported in the state so far this year, which is more than all other years combined. Four of the Texas deaths were reported on Tuesday.

Officials last week started aerial spraying for mosquitoes in Dallas County. But it's too soon to measure the effect _ it takes between three and 14 days for people to develop symptoms after being infected by a mosquito.

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. (AP)

<관련 한글 기사>

죽음의 모기 바이러스 ‘최악’, 41명 사망!

미국에서 최근 텍사스주를 중심으로 모기로 감염되는 웨스트나일 바이러스의 피해가 급격히 확산하고 있어 보건당국에 비상이 걸렸다.

22일(현지시간) 미국 질병통제예방센터(CDC)에 따르면 올여름 웨스트나일 바이러스로 인한 사망자가 최소 41명에 달했으며 지금까지 확인된 환자 수만 1천118명 에 달하는 것으로 집계됐다.

이는 지난 1999년 미국에서 첫 감염자가 발생한 이후 최악의 수준이다. 지난해 전체 감염자와 사망자는 각각 712명과 43명이었다.

특히 통상 웨스트나일 바이러스가 8월 중순에 가장 극성으로 부린 뒤 이후에도 상당기간 활동을 계속한다는 점을 고려하면 앞으로 피해는 더 늘어날 것으로 우려되 고 있다.

또 잠복 기간 때문에 발병 이후 의사를 찾기까지 시차가 있어 실제 감염자는 보 고된 사례보다 훨씬 많을 것으로 추정됐다.

CDC의 라일 피터슨 국장은 "웨스트나일 바이러스 감염 사례가 최근 몇 주일간 급격히 늘어났다"면서 "지난 겨울 날씨가 따뜻했고 봄과 여름이 빨리 찾아와 바이러 스가 빨리 퍼진 것으로 보인다"고 설명했다.

지역별로는 텍사스주에서 지금까지 21명이 웨스트나일 바이러스로 목숨을 잃은 것으로 확인됐으며 최근 사망한 4명도 감염 가능성이 높다고 현지 보건 당국자는 전했다.

이에 따라 텍사스주 댈러스 인근 지역에서는 항공기를 동원한 대규모 방역 작업을 했다고 현지 언론들은 보도했다.

1937년 우간다에서 처음 발견된 웨스트나일 바이러스는 감염된 조류의 피를 빨아들인 모기에 의해 사람에게 옮겨진다.

발진과 두통 등의 증세를 일으키며 심한 경우 고열과 실명, 신체 마비로 이어지고 노약자나 어린이와 같이 면역체계가 약한 감염자는 뇌염이나 수막염으로 목숨을 잃을 수도 있다.