West Nile Virus

WNV is a virus that mostly spreads to people through the bites of infected mosquitoes.

Most people who are infected will not show any symptoms, while about 20% will develop a fever along with other mild symptoms.

About 1 in 150 people who are infected will develop a severe illness affecting the central nervous system, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord), which can be life-threatening.

Mosquitoes get the WNV by feeding on infected birds. Later, they pass the virus on to humans, horses and other animals through their bites. People and animals can also become infected by coming into contact with other infected animals, their blood, or other tissues. 

WNV can also be transmitted through organ transplant, blood transfusions, during pregnancy delivery, and through breast milk, though this is rare. To date, no human-to-human transmission of WNV through everyday contact has been documented. 

You can lower your risk of getting WNV by protecting yourself from mosquito bites through the following measures.

• Wear light clothing that covers most of your body, such as light long sleeves and pants.
• Use window and door screens to keep mosquitoes out of the house.
• Apply mosquito repellents according to the manufacturer’s instructions. Insect repellent should be applied on a child by an adult. 
• Sleep in an air-conditioned room or use fans, and use mosquito nets for baby carriers.

You can prevent mosquito breeding by:

• removing stagnant water where mosquitoes typically bread, such as in pots, water containers, and trash with accumulated rainwater;
• disposing of waste properly; and
• securely covering, emptying and regularly cleaning and disinfecting water storage containers.

Most people who are infected will not show any symptoms, while about 20% will develop a fever with other symptoms.

The most common symptoms of infection with WNV include:

• fever
• headache
• tiredness and body aches 
• nausea and vomiting
• occasionally a skin rash (on the torso) 
• swollen lymph glands.

The symptoms of severe disease (also called neuroinvasive disease, such as West Nile encephalitis or meningitis or West Nile poliomyelitis) include: 

• headache
• high fever
• neck stiffness
• stupor
• disorientation
• coma 
• tremors
• convulsions
• muscle weakness
• paralysis.

Serious illness can occur in people of any age, but older people and immunocompromized persons have the highest risk. If you experience any of the severe symptoms, seek medical care immediately.

If you get WNV, it’s important to:

• rest
• drink plenty of liquids
• take medicine for pain relief
• watch for severe symptoms
• contact your doctor as soon as possible if you notice any severe symptoms.

There are no specific medicines to treat West Nile disease. The treatment focuses on relieving symptoms and supportive care. If you experience any severe symptoms, seek immediate medical care.