Polio-Like Symptoms With West Nile Virus

Summertime – children stay indoors, no swimming is permitted at the local pond and parents are frightened of a virus that is sweeping the nation. It’s an illness that paralyzes people and can kill.

No, this isn’t a description of the polio epidemics that panicked people in this country in the late 40s and early 50s. Instead, it could be West Nile virus (WNV) that could be causing polio-like symptoms, which is being found in some people who have the disease.

Research published in The New England Journal of Medicine found some people with WNV have muscle weakness leading to paralysis that is eerily similar to polio symptoms. The most severe symptom thus far observed with WNV has been encephalitis, which also has muscle weakness associated with it. These findings, however, indicate a different type of severe muscle weakness called acute flaccid paralysis.

Are we at risk?

“Our report is the first that we know of that shows a purely paralytic form of West Nile in a young, otherwise healthy person,” says Owen B. Samuels, M.D., director of NeuroCritical Care and assistant professor of Neurology and Neurological Surgery at Emory University School of Medicine in Atlanta.

Samuels adds that while patients with a severe case of WNV may experience polio-like symptoms, the likelihood of developing severe symptoms is not very high.

“Legions of people are not coming in with polio symptoms, although we do not exactly know what is in store for the future,” he says.

Another expert finds that health care providers’ ignorance plays a role. “The condition has been unrecognized by the medical community because the symptoms were ascribed to other diseases, such as Guillain-Barré,” says Dobrivoje S. Stokic, M.D., director of the Center for Neuroscience and Neurological Research at the Methodist Rehabilitation Center in Jackson, Miss. and one of the authors of another report in The New England Journal of Medicine. Guillain-Barré is a rare inflammation of nerves that usually follows a viral infection, injury, surgery, vaccination or stress.

“After three patients infected with West Nile virus in Mississippi showed polio-like symptoms, we immediately alerted the Centers for Disease Control and Prevention (CDC) in Atlanta to look for similar cases in the region,” Stokic says. Not surprisingly, three other patients were soon discovered in Louisiana, and public health workers were informed of findings in the CDC’s Morbidity and Mortality Weekly Report.

Samuels adds that polio-like symptoms in severe cases of WNV may have occurred in the past but only now are being identified and written about. He says we may see an increase in the disease being reported since physicians can now be on the lookout for these symptoms.

In the past, a person might have been misdiagnosed as having Guillain-Barré syndrome, a more common cause of muscle weakness and paralysis in the United States. This syndrome is unrelated to polio, and to date, there are no proven effective treatments.

According to Stokic, we need to understand that most people who have been infected by the WNV are unaffected by the disease and only the most severe cases exhibit muscle weakness. Also, he says, there will be long-term follow-up on the patients he and his colleagues studied to see if the disease has the consequences typically associated with polio.

The CDC reports WNV is rare. Fewer than 1 percent of people who are bitten by mosquitoes develop any symptoms of the disease and relatively few mosquitoes actually carry WNV. Also, most people who have been infected with the virus don’t have symptoms or may have mild symptoms. It is rare for the virus to lead to a severe illness or death. However, the risk for someone older than 50 is higher. This virus cannot be spread by person-to-person contact.

Know the signs

While most people infected with the WNV don’t show symptoms, about 20 percent will develop some mild symptoms of the disease which include:

  • Fever.
  • Headache.
  • Body aches.
  • Sometimes a skin rash on the trunk of the body.
  • Swollen lymph glands.

The following symptoms may indicate a severe case of West Nile disease and should be reported to your doctor immediately:

  • Headache.
  • High fever.
  • Stiff neck.
  • Stupor.
  • Feeling disoriented.
  • Tremors.
  • Convulsions.
  • Muscle weakness.
  • Paralysis.
  • Coma.

Samuels says, “Although people should be aware and concerned of these recent reports of the severity of West Nile virus, they (the reports) remain uncommon and should be kept in a reasonable perspective. People should use common sense when going outside, especially in the summer months.”

Samuels also offers the following prevention tips when going outside during mosquito season:

  • Cover exposed skin.
  • Wear a hat.
  • Use DEET repellent.

Learn more about West Nile Virus? Here are questions and answers:

How do people get the West Nile Virus?

Mosquitoes pick up the virus after feeding on infected birds that may have had the disease for several days. After the virus incubates in the mosquito for about 72 hours, the bug can transfer the virus to humans and animals. Less than 1 percent of mosquitoes actually carry the virus.

What are the symptoms and what should people do if they think they are infected?

The illness is rare. Most people infected won’t have any illness. But 20 percent of those infected have mild symptoms. And from that group, 1 in 150 develop severe infections. After incubating for 72 hours, mild symptoms that might appear include headaches, flu-like symptoms, sore neck and sensitivity to light. If you think you have it, see a doctor right away. Symptoms of mild cases last a few days but then go away. Severe forms may last several weeks.

When did we start hearing about this disease?

Recent outbreaks surfaced in Africa in the mid 1990s. New York City was the first area in this country to report outbreaks with 60 human cases in 1990. Three people died during that first U.S. outbreak.

How many cases have been reported?

The virus has now gone coast-to-coast – from New York to California. We have 43 states reporting outbreaks, but those cases include birds and horses. As of this week, 1,201 human cases and 46 deaths are reported since the outbreak began in this country 12 years ago.

Who’s most at risk?

We urge people who are over 50 to be especially careful because their immune systems aren’t as good as they used to be. Case fatality rates range from 3 percent to 15 percent and are highest among the elderly.

Do we have a vaccine?

One is in development and is being tested on horses this year. But a human vaccine is still years down the road.

What happens to the virus during the winter?

Because the disease is fairly new to scientists, we are still learning how the virus survives. We know that if winters are harsh, the outbreaks aren’t as severe during the summers.

How do people protect themselves?

Wear bug spray containing DEET, an active ingredient found in bug sprays and labeled on products as N,N-diethyl-m-toluamide or, sometimes, N,N-diethyl-3-methylbenzamide. Wear long sleeves and pants. Babies and young children should wear repellents with only 10 percent DEET. The typical amount for the rest of the population should be 50 percent. Also, towns and cities, both rural and urban, are spraying for mosquitoes. Be sure not to have standing water in your yard. Mosquitoes lay their eggs in standing water. Also, stay indoors at dawn and dusk.

External Sources

New England Journal of Medicine
Center for Neuroscience and Neurological Research at the Methodist Rehabilitation Center
Emory University School of Medicine
The Centers for Disease Control and Prevention