Fast Facts: West Nile virus 101

The influx of rain this season has caused severe flooding across the Southeast, particularly in Texas and Oklahoma. Rushing water is dangerous, but when water stops moving, it creates the perfect breeding ground for something just as threatening: West Nile virus (WNV) bearing mosquitoes.

Reports of WNV-positive mosquito traps have already sprung up in Dallas, which means it’s time to learn the basics about the disease. To help educate us about the most important WNV facts, we sat down with Chetan Jinadatha, M.D., M.P.H., assistant professor at the Texas A&M Health Science Center College of Medicine and infectious disease expert.

1. What is the West Nile virus?

The West Nile virus is an arthropod-borne virus that can cause encephalitis (inflammation of the brain), meningitis (inflammation of the lining of the brain and spinal cord) or can even be fatal, in severe cases.

The virus has been detected in 48 states, and cases have occurred every summer since 1999, when it first made an appearance in the U.S.

2. How is it contracted?

Since most people are infected through mosquito bites, the virus is most prevalent during the summer months (from June to September), when mosquitoes are more likely to breed. Mosquitoes contract the disease by feeding on infected birds.

WNV is not contagious through normal person-to-person contact. In rare cases, the virus can be transmitted via blood transfusion, organ transplant, or from mother-to-baby during pregnancy, delivery and breastfeeding.

The people most at risk for contracting the virus are those who work outdoors or participate in outdoor activities. However, anyone living in an area where WNV is present in mosquitoes is at risk.

3. What are the symptoms of WNV?

Two to six days after someone is bitten, symptoms usually begin to show (if they do at all), but it can take up to 14 days for symptoms to present themselves. According to the Centers for Disease Control and Prevention (CDC), 70 to 80 percent of people infected show no symptoms at all. The remaining 20 percent are more likely to develop febrile illness, which is similar to flu-like symptoms:

• Headache
• Body aches and joint pains
• Nausea or vomiting
• Diarrhea
• Rash

Most people who develop these symptoms make a complete recovery, but weakness and fatigue can last for weeks or months after infection.

In rare but extreme cases (less than one percent of the time), people will develop a serious neurological illness such as encephalitis or meningitis. These illnesses can cause symptoms such as:

• Headache
• High fever
• Neck stiffness
• Disorientation
• Coma
• Tremors
• Seizures
• Paralysis

These neurological effects may take several weeks or months to recover from and, in some cases, can be permanent. Approximately 10 percent of people who develop a neurological illness from WNV will die.

4. Can it be treated?

Unfortunately, there are no vaccines or medications to treat WNV. For people who develop symptoms, over-the-counter pain relievers and fever reducers can be used to relieve some symptoms. People with mild symptoms usually recover on their own, but symptoms may last for several weeks after onset. In more severe cases, patients may need to be hospitalized to receive supportive treatment for neurological symptoms.

If you suspect that you or a family member has the virus, consult a health care provider to undergo an exam and further testing. Tests using blood samples or spinal fluid may be used to detect antibodies the immune system creates to fight infection that is present in the body.

5. Are there any actions you can take to prevent the disease?

Since there is currently no vaccine, the best method of protection is to prevent mosquito bites. People can do this by applying insect repellant whenever they go outdoors. Repellants using DEET, picaridin, IR3535 and some oil of lemon eucalyptus and para-menthane-diol products typically provide longer-lasting protection.

In addition to repellant, wear long sleeves and pants, especially during dawn and dusk, when mosquitos are most active. Installing or repairing window and door screens can help limit the number of mosquitoes that enter indoors, as well as using air conditioning when you can. Reduce the number of mosquitoes around your house by draining any nearby standing water. Empty out water-filled containers such as flowerpots, gutters, buckets, pool covers, pet water dishes and birdbaths to help limit the number of mosquitoes that breed nearby.

For more information, the CDC has many resources about protecting yourself against the West Nile virus.