West Nile Virus
What are the symptoms of the virus?
- People typically develop symptoms between three and 14 days after they are bitten by the infected mosquito.
- About 1 in 150 people infected with the virus will develop severe symptoms that can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent.
- Up to 20 percent of those infected have symptoms such as fever, headache, body aches, nausea, vomiting and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms can last for as short as a few days, though even healthy people have become sick for several weeks.
- Approximately 80 percent of people who are infected will not show any symptoms.
How does it spread?
- Most often, the virus is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread the virus to humans and other animals when they bite.
- In a very small number of cases, the virus also has been spread through blood transfusions, organ transplants, breastfeeding and even during pregnancy from mother to baby.
What can I do to prevent the virus?
- The easiest and best way to avoid the virus is to prevent mosquito bites.
- When you are outdoors, use insect repellent containing an EPA-registered active ingredient. Follow the directions on the package.
- Many mosquitoes are most active at dusk and dawn. Be sure to use insect repellent and wear long sleeves and pants at these times or consider staying indoors during these hours.
- Make sure you have good screens on your windows and doors to keep mosquitoes out.
- Get rid of mosquito breeding sites by emptying standing water from flowerpots, buckets and barrels.
- Change the water in pet dishes and replace the water in bird baths weekly. Drill holes in tire swings so water drains out. Keep children’s wading pools empty and on their sides when they aren’t being used.
How is it treated?
In cases with milder symptoms, people experience symptoms such as fever and aches that pass on their own. In more severe cases, people usually need to go to the hospital where they can receive supportive treatment including intravenous fluids, help with breathing and nursing care.
What is the risk of getting sick from the virus?
People older than 50 are more likely to develop serious symptoms if they do get sick and should take special care to avoid mosquito bites. Being outside means you’re at risk. The more time you’re outdoors, the more time you could be bitten by an infected mosquito. Risk through medical procedures is very low.
All donated blood is checked for the virus before being used.
Source: Centers for Disease Control and Prevention
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.
As of Tuesday, 1,590 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 66 deaths this year, according to the CDC.
And cases seem to be accelerating: About 400 of the cases were reported in just the last week.
As of Tuesday, 21 people tested positive for the virus in Georgia, according to the U.S. Geological Survey website.
Sandy Bozarth, infection prevention and control coordinator for Northeast Georgia Medical Center, said one person has tested positive at the hospital in the last six months. That person’s symptoms were not severe enough to be admitted into the hospital.
Bozarth said depending on a person’s symptoms, the lab will do a blood test to check for antibodies of the virus this time of year.
She said it is common to see a case every now and then. She said she does expect to see more cases this year based on the way the illness is presenting itself in other areas of the country.
“We’ve tested for it in other patients within the last six months ... and that’s the only positive that we’ve had,”
Other positive tests have turned up in Forsyth, Fulton, Cobb and Bartow counties, according to USGS.
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.
“Approximately 80 percent of people, about 4 out of 5, who are infected with West Nile Virus will not show any symptoms at all,” wrote Dave Palmer, public information officer for District 2 Public Health, in an email.
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. It takes between three and 14 days for people to develop symptoms after being infected by a mosquito.
Palmer said severe symptoms could last for several weeks and neurological effects may be permanent.
The people who are at a higher risk of developing a severe illness if they do get sick are those over 50 or those with an immune deficiency. Palmer said people over 50 should take special care to avoid mosquito bites.
Many illnesses probably go unreported, especially milder cases. In this year’s case count, more than half are severe, CDC officials said.
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. Mosquitoes are most active at dusk and dawn.
Palmer suggested drilling holes in tire swings and to keep children’s wading pools on their sides when not being used to make sure water drains out.
“Being outside means you’re at risk. The more time you’re outdoors, the more time you could be bitten by an infected mosquito. Pay attention to avoiding mosquito bites if you spend a lot of time outside, either working or playing,” Palmer said.
The Associated Press contributed to this report.