Question: What is West Nile virus?
Answer: It’s an infectious disease mainly spread through the bite of infected mosquitoes, who get it from infected birds they’ve previously fed on.
Q: How long are people sick?
A: Anywhere from a few days to several weeks.
Q: How is West Nile virus treated?
A: There’s no specific treatment for the disease. Instead, symptoms focus on the symptoms, including reducing fever and body aches. In more severe cases, IV fluids, respiratory support and prevention of secondary infections are the focus of treatment.
Q: Can West Nile virus be fatal?
A: Yes, though most people who are infected never get sick.
Q: What’s the best way to prevent the disease?
A: There’s no vaccine to prevent West Nile, so the best bet is prevent mosquito bites. Use an EPA-approved mosquito repellent (DEET; picaridin; oil of lemon eucalyptus or PMD; or IR3535), wear long pants and long sleeves outdoors and stay indoors at dusk and dawn, when mosquitoes are most active. Getting rid of areas where mosquitoes can breed also cuts down on the likelihood of infection. Eliminate standing water in flower pots and planters, old tires, gutters and other sites, and use mosquito dunks in ponds and larger sources of water.
As Ohio sees its first West Nile virus death and human infections jump 40 percent a week nationally, health officials say they can’t predict how bad West Nile could get this year.
On Thursday, the state reported 51 cases, including one fatality. A Hamilton County man died Wednesday of encephalitis related to the infection. He was 76.
In the region, Clark County has seen the most human cases with 5 and Montgomery County has had 4. Warren, Butler and Miami each have 1 case.
Last year, Ohio reported 21 cases, including one fatality.
Nationally, the Centers for Disease Control and Prevention reported nearly 1,600 cases this week, including at least 67 fatalties. Almost half of the infections and deaths were in Texas.
“I’m not going to predict how many cases we’ll get,” said Dr. Mary DiOrio, an epidemiologist with the Ohio Department of Health. “I do expect to see more cases, and we know this has already been one of our worst seasons. Hopefully, we can help slow down the cases and protect people from getting West Nile by getting rid of the mosquitoes that are spreading the disease.”
In the Midwest and many other parts of the country, mild winter and spring, followed by near-record summer heat and drought conditions make for a perfect swarm of breeding conditions for the Culex mosquitoes that carry the virus.
More mosquitoes mean more exposure to the virus, DiOrio said. “There are a lot of mosquitoes out there that are infected, so a lot more people are being exposed to the virus,” she said.
Mosquitoes contract the disease when they feed on infected birds, then pass the virus to humans when they feed on them.
Nationally, it’s been the worst summer for the disease since it was identified in the U.S. in 1999. Ohio is seeing the highest levels of West Nile virus in mosquitoes since the state began tracking it in 2002.
Richard Gary, state public health entomologist for the Ohio Department of Health said his colleagues at ODH and local health department started finding West Nile as soon as they started looking for it this year.
“The rate of infection in those mosquitoes went up quite rapidly, right from the get-go,” he said. “What we saw this year was an increase that was much faster and much higher than anything we had seen since 2002. We knew the environment was right for mosquito infections, and now we’re subsequently having an increase in the human infections.”
In recent weeks, mosquito samples collected in Montgomery County have shown a third are positive for West Nile virus, said Bill Wharton, spokesman for Public Health - Dayton & Montgomery County. “Earlier this summer it was one out of four,” Wharton said. “It just keeps getting worse.”
Wharton reminded residents to get rid of standing water on their property as the best defense against mosquitoes, which lay eggs in water. With heavy rain expected Saturday and Sunday, residents should look around their yards and get rid of water in planters, downspouts, tires and gutters to help reduce their risk of mosquito bites, he said. Clogged gutters are a common place for mosquitoes to breed, he said.
Only about 20 percent of people who are infected with West Nile virus go on to develop symptoms, and less than 1 percent develop serious illness, including meningitis and encephalitis from their infections. But data show more than half of the cases reported nationally are neuroinvasive.
It’s likely a sign that people who are developing the mildest symptoms aren’t seeing their doctors, so they’re not being tested for the disease and their illnesses aren’t being reported, DiOrio said.
“Like a lot of diseases, the most severe cases are the ones being reported,” she said. “That often happens. The people with the milder symptoms just take care of themselves at home, get some extra rest and don’t seek medical attention.”
Most people who develop symptoms with West Nile virus feel like they have the flu, said Catherine Bacheller, an infectious disease specialist with Kettering Health Network. They have a fever, body aches, fatigue and sometimes, a rash.
But in a small percentage, the virus manages to slip past the body’s defenses and attack the central nervous system, causing inflammation in the brain, the spinal cord and the membranes that line both. Symptoms for them include high fever, severe headache, confusion or delirium, and in some cases, muscle weakness or loss of muscle control, often on one side of the body. Anyone with those symptoms should see a doctor immediately.
The early spring meant mosquitoes became active longer, with time to catch and spread West Nile longer and to breed longer, Gary said. The virus is more easily spread during hot weather, and the birds that are the reservoir for the virus are also more stressed by high temperatures, and so more likely to both contract and spread it, he said.
And dry conditions mean more stagnant water left behind in drainage ditches and catch basins. The water tends to be rich with rotted leaves and other organic material. “It’s a kind of nasty little soup that those mosquitoes do quite well in,” he said.
The outbreak should end once it’s cold enough to kill off the mosquitoes that carry it.
“One or two good frosts should put an end to it,” Gary said. “That doesn’t mean we’ll stop seeing human cases reported immediately.”
It can take up to 15 days between the time a person is infected and they feel sick. Then they have to get to a doctor, who has to order tests, and it takes a few days for the test results to come in.
“There’s often quite a few weeks to go between a person being bitten by an infected mosquito and the disease being reported,” he said.
About the Author