West Nile virus
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What is West Nile virus?
West Nile virus (WNV) is an illness caused by a virus that is spread through mosquito bites. About 80% of people who are infected with WNV do not feel sick. For people who do feel sick, symptoms can include fever, headache, tiredness, nausea, vomiting, swollen lymph glands, and a rash on the chest, stomach, or back. Symptoms usually last from a few days to a few weeks. In rare cases, more serious symptoms of WNV can occur. Serious symptoms include high fever, headache, neck stiffness, lack of energy, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis.
WNV can also be spread through blood transfusions, transplants, breastfeeding, and from mother to baby. However, these types of cases are rare; most WNV cases are caused by mosquito bites.
Who is at risk?
Travelers who go to Africa, Europe, the Middle East, west and central Asia, or North America are at risk of getting West Nile virus. Travelers who plan to spend a lot of time outdoors or who will be in areas with a lot of mosquitoes are at increased risk of WNV. Travelers over 50 years of age are at the highest risk for severe disease if they get WNV.
What can travelers do to prevent West Nile virus?
There is no vaccine or medicine that prevents West Nile virus. Travelers can protect themselves by preventing mosquito bites.
Prevent mosquito bites:
- Cover exposed skin by wearing long-sleeved shirts, long pants, and hats.
- Use an appropriate insect repellent as directed.
- Higher percentages of active ingredient provide longer protection. Use products with the following active ingredients:
- DEET (Products containing DEET include Off!, Cutter, Sawyer, and Ultrathon)
- Picaridin (also known as KBR 3023, Bayrepel, and icaridin products containing picaridin include Cutter Advanced, Skin So Soft Bug Guard Plus, and Autan [outside the US])
- Oil of lemon eucalyptus (OLE) or PMD (Products containing OLE include Repel and Off! Botanicals)
- IR3535 (Products containing IR3535 include Skin So Soft Bug Guard Plus Expedition and SkinSmart)
- Always follow product directions and reapply as directed:
- If you are also using sunscreen, apply sunscreen first and insect repellent second.
- Follow package directions when applying repellent on children. Avoid applying repellent to their hands, eyes, and mouth.
- Use permethrin-treated clothing and gear (such as boots, pants, socks, and tents). You can buy pre-treated clothing and gear or treat them yourself:
- Treated clothing remains protective after multiple washings. See the product information to find out how long the protection will last.
- If treating items yourself, follow the product instructions carefully.
- Do not use permethrin directly on skin.
- Stay and sleep in screened or air conditioned rooms.
- Use a bed net if the area where you are sleeping is exposed to the outdoors.
If you are bitten by mosquitoes:
- Avoid scratching mosquito bites.
- Apply hydrocortisone cream or calamine lotion to reduce itching.