West Nile Virus

Symptoms

What are the symptoms of West Nile (WN) virus infection?

Many infected people have no symptoms and do not get sick or have only mild symptoms. When infection does cause illness, symptoms will usually appear within two to 15 days. The extent and severity of symptoms vary widely from person to person.

In mild cases, there may be flu-like symptoms, including fever, headache and body aches. Some people may also develop a mild rash, or swollen lymph glands.

Some individuals have weaker immune systems, and they are at greater risk of developing symptoms and health effects that are more serious, including meningitis and encephalitis. Meningitis is inflammation of the lining of the brain or spinal cord. Encephalitis is inflammation of the brain itself. These conditions can be fatal.

In such cases, symptoms could include the rapid onset of severe headache, high fever, stiff neck, nausea, difficulty swallowing, vomiting, drowsiness, confusion, loss of consciousness, lack of coordination, muscle weakness and paralysis. During 2002, several other symptoms of WN virus were identified including movement disorders, parkinsonism, poliomyelitis-like syndrome and muscle degeneration. Anyone who has a sudden onset of these symptoms should seek immediate medical attention.

Who is at risk for serious health effects from WN virus?

While persons of any age and health status can be at risk for serious health effects associated with West Nile virus infection, the overall risk of serious health effects increases with age. People with weaker immune systems are considered to be at greater risk for serious health effects. This higher risk group includes:

• people with chronic diseases, such as cancer, diabetes, alcoholism, or heart disease
• people that require medical treatment that may weaken the immune system, i.e. chemotherapy.

Although individuals with weaker immune systems are at greater risk, WN virus can cause severe health effects for people of any age and any health status. This is why it is so important to reduce the risk of getting bitten by mosquitoes. Anyone exposed to mosquitoes in an area where WN virus has been detected is at some degree of risk for infection.

What are the long-term effects of WN virus?

Because WN virus is an emerging disease, the long-term effects are not fully understood. Studies to date show that some people with serious symptoms and health effects recover completely, while others experience prolonged health problems. These problems can include:

• physical effects, such as long-term muscle weakness and paralysis, fatigue and headache
• cognitive effects, such as confusion, depression, problems with concentration and memory loss
• functional effects, such as difficulty with preparing meals, going out, shopping, etc.

Scientists do not know why some people recover while others continue to have varying degrees of health problems.

Protect Yourself & Your Family

People can get West Nile virus if they are bitten by an infected mosquito. While, its important to remember that the risks of being bitten by an infected mosquito are low and the chances of becoming seriously ill are even lower, anyone who is exposed to mosquitoes in an area that has West Nile virus has the potential to become infected.

What can I do to protect myself and my family?

To protect yourself and your family, you should avoid being bitten by mosquitoes. You can take action on two fronts:

1. Minimize your exposure to mosquitoes:

• When going outdoors, use insect repellents that contain DEET or other approved ingredients.
• Try to avoid spending time outdoors at dawn and at dusk when mosquitoes are most active.
• Wear protective clothing such long-sleeved shirts, long pants and a hat. Light coloured clothing is best because mosquitoes tend to be more attracted to dark colours.
• Make sure that door and window screens fit tightly and have no holes that may allow mosquitoes indoors.

2. Eliminate mosquito breeding sites around your home and cottage:
Mosquitoes lay eggs in standing water and it takes about four days for the eggs to grow into adults that are ready to fly. Even a small amount of water, for example, in a saucer under a flower pot, is enough to act as a breeding
ground. As a result, it is important to eliminate as much standing water around your property as possible by:

• Regularly draining standing water from items like pool covers, saucers under flower pots, recycle bins, garbage cans, etc.
• Remove old unused items from around your property including old tires, that have a tendancy to collect water.
• Change the water in wading pools, bird baths, pet bowls and livestock watering tanks twice a week.
• Cover rain barrels with screens.
• Clean out eaves troughs regularly to prevent clogs that can trap water.
• If you have an ornamental pond, consider getting fish that will eat mosquito larvae.

How about using pesticides?

Over the counter products that are designed to get rid of garden pests aren't effective for overall mosquito control. Regarding the use of other pesticides, only workers who are licensed by provincial authorities and are trained in the safe use of pesticies can carry out mosquito control programs. Decisions on whether or not to use pesticides to control the spread of West Nile virus in your community will be made by local and provincial health authorities.


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