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         Sunday, March 29, 2015
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What are the symptoms of West Nile virus?

  • Most people who have been infected with WNV experience no symptoms and do not get sick.
  • Approximately 20 per cent of people who become infected will develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash. Most people with this type of West Nile virus disease recover completely, but fatigue and weakness can last for weeks or months.
  • Less than 1 per cent of people infected with WNV will develop a more serious illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues). This serious type of illness is called WNV neuroinvasive disease. Symptoms of WNV neuroinvasive disease can include headache, high fever, neck stiffness, disorientation, coma, tremors, seizures, or paralysis.
  • Recovery from severe disease may take several weeks or months. Some of the neurologic effects may be permanent. About 10 percent of people who develop neurologic infection due to WNV will die.

When will symptoms appear if I am infected with West Nile virus?

When infection causes illness, symptoms usually begin 2 to 15 days following a bite from an infected mosquito.

How long will symptoms last if I become ill with West Nile virus?

The length and extent of illness will vary widely from person to person, and will depend on the severity of symptoms. Symptoms may last from a few days to up to several weeks, while severe neurological effects may continue for a longer period of time.

Are there long-term effects of WNV?

Most people with mild symptoms recover completely within days to weeks. For people who get the rare neuroinvasive form of the disease, recovery may take several weeks to months. Unfortunately, some of the neurologic effects may be permanent.

Age is a significant predictor of recovery. Younger people are more likely to recover faster and completely, compared to those in the older age groups.

Who is most likely to get sick after being infected with WNV?

People with weaker immune systems and people with chronic diseases are at greater risk for serious health effects. This may include people with cancer, diabetes, alcoholism, heart disease, or people undergoing medical treatment that may weaken the immune system, such as chemotherapy.

The risk of serious illness increases with age. However, anyone exposed to mosquitoes in an area where WNV has been detected is at risk for infection.

What should I do if I think I have West Nile virus?

You do not need to seek medical attention for mild symptoms, as they tend to improve on their own.

If you are concerned about your symptoms, contact your health professional or call HealthLine at 811.

If you develop symptoms of severe WNV illness, such as severe headaches, persistent high fever with stiff neck, confusion, seizures, or paralysis, seek medical attention immediately.

How can I avoid getting WNV?

Minimize your exposure to mosquito bites:

  • Use appropriate insect repellent when outdoors;
  • Cover up. Wear light coloured, loose fitting, long-sleeved tops and long pants when outdoors; and
  • Reduce the amount of time spent outdoors between dusk and dawn. The peak mosquito hours are around dusk and dawn, but Culex mosquitoes will also bite during the night.

Reduce mosquito habitats:

  • Culex mosquitoes lay their eggs on standing water. Even small amounts of water, allowed to stand for a week or more, may produce adult mosquitoes;
  • Regularly clean and empty containers that can collect water such as bird baths and eaves troughs;
  • Clear yards of old tires and other items that can collect water;
  • Ensure rain barrels are covered with mosquito screening or are tightly sealed around the downspout; and
  • Maintain door and window screens so they fit tightly and are free of holes.

Adult mosquitoes like to rest in long grass and sheltered shady areas. You can reduce your exposure to mosquitoes by regularly maintaining these areas around your home:

  • Cut the grass around your home;
  • Trim hedges and trees around doorways and outdoor seating areas (decks, patios, etc.); and
  • Keep bushes, shrubs and lawns clear of overgrowth and debris.

What about outdoor recreation and work?

People who spend a lot of time outdoors for recreation (e.g. camping, golfing) or work (e.g. farming, construction) should follow the same self protection measures as anyone else. These precautions are especially important in back country areas where there are large amounts of shallow, standing water.

What repellents are considered appropriate?

Use DEET containing personal insect repellents on exposed skin. The concentration of DEET should be no higher than 30 per cent for adults and no higher than 10 percent for children. Products with DEET are the most effective. DEET is safe and doesn't require a heavy application - a light spray will do.

Repellents with Icaridin and oil of lemon eucalyptus are also effective. Some repellents can also be applied to clothing.

Always read the product label for directions on use of any repellent.

Visit the Health Canada website for more information
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How would an infected person be treated for WNV?

There is no specific treatment, medication, or cure for WNV. Serious cases are treated with supportive therapies to ease symptoms and prevent secondary infections. Supportive therapies include hospitalization, intravenous (IV) fluids, airway management, respiratory support and good nursing care. Physical or occupational therapy may be needed to help with possible long-term effects.

Isn’t it likely that most people have already been exposed to West Nile Virus (WNV) and have developed immunity to it?

Although West Nile Virus has been circulating in Saskatchewan for several years, the majority of people have not been exposed to the virus. In addition, the length of immunity after infection is unknown. Any immunity you may develop may decrease over time or if health conditions compromise the immune system. Therefore, it is not wise to assume you are immune. People should still take precautions.

Is there a human vaccine available for WNV?

Currently there is no human vaccine available for WNV. There are a number of companies currently working on a vaccine, but they are still in the development phase.

Horses bitten by infected mosquitoes can become seriously ill and die. There is a vaccine for horses.

Younger domestic birds have also been affected by WNV. Disease due to WNV has not been reported among cattle. Research has shown that weaning pigs may be susceptible to the virus. Cases of infected dogs and cats have been reported rarely. Dogs and cats seldom show any clinical symptoms of the disease. Cats may occasionally have a mild fever.

Where can I find more information about WNV?

For more information, including Risk Maps and Surveillance Results, see .

You can also visit Healthline Online at .

Related Links

Information about WNV risk levels, surveillance results, awareness and prevention.

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