The early bird may get the worm, but in several parts of the United States this spring, those birds are getting
West Nile Virus.
The winter cold and flu season is barely over, and the new mosquito season won't really get rolling for a few more weeks, but the Centers for Disease Control and Prevention (CDC) already is reporting the presence of West Nile Virus in mosquitoes, birds and other animals in nine states.
There even is confirmation of a human case in Ohio. Last year's first human case wasn't confirmed until July.
|
 |
|
|
Neurons that have been infected with West Nile Virus. |
|
"It certainly is early for the virus to be reported in humans, but with a mild winter in many parts of the country, it's possible significant numbers of infected mosquitoes survived," says Michael Diamond, M.D., Ph.D., assistant professor of medicine, of molecular microbiology and of pathology and immunology at <<>> in St. Louis. "It's too soon to tell how bad this summer might get, but it's always important to take precautions."
The virus poses a threat mainly to certain wild birds — more than 100 species have been killed, with crows, blue jays and some sparrows most commonly infected by the virus — and some livestock, especially horses. But it can infect people, too.
 |
| Michael S. Diamond, M.D., Ph.D. |
Symptoms of West Nile fever — usually a mild illness that lasts a few days — include fever, headache, body aches and sometimes a skin rash and swollen lymph glands.
People can become infected when a mosquito bites a virus-laden bird and then bites a human. An estimated 20 to 25 percent of people who become infected develop the flu-like symptoms of West Nile fever, and a much smaller number go on to develop meningitis or West Nile encephalitis, an inflammation of the brain that can be fatal.
Signs and symptoms include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis.
West Nile Virus first appeared in the United States in 1999. In that initial outbreak, there were 62 human cases of the virus in the United States, but by last summer that number had grown to 9,858 cases in 45 states and the District of Columbia. More than 2,800 people went on to develop severe disease — such as West Nile meningitis and West Nile encephalitis — and 262 died. Last year in Missouri, WNV caused illness in 64 people, and eight of them died.
The people at greatest risk are those 50 and older and those with weakened immune systems. Younger people also can acquire the infection, but their risk is significantly lower.
Heading into the summer of 2004, the question is: How great a threat will the virus pose this year, and how soon will the peak season begin?