Murray Valley Encephalitis virus

What is Murray Valley encephalitis?

Murray Valley encephalitis (MVE) is a disease caused by a virus that is spread through mosquito bites. Most people who are infected with the virus do not feel sick. Some people do develop symptoms such as fever, headache, nausea, vomiting, and tiredness. People who get the virus may also develop severe disease. Symptoms of severe disease are confusion, sleepiness, trouble speaking, lack of coordination, and brain infection. In very rare cases, long-term disability or death can occur.

Who is at risk?

Travelers to New Guinea and remote northwestern Australia or southeastern Australia are at risk of getting MVE virus. (See map.) The virus is more common during heavy rainfall, flooding, and hot weather. Travelers who plan to spend a lot of time outdoors or will be in an area with a lot of mosquitoes are at increased risk of getting the virus.

What can travelers do to prevent Murray Valley encephalitis?

There is no vaccine or medicine that prevents MVE. Travelers can protect themselves from MVE by preventing mosquito bites.

Prevent mosquito bites:

man spraying insect repellent on his arm
  • 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.

If you feel sick and think you may have MVE:

  • Talk to your doctor or nurse if you feel seriously ill, especially if you have a fever.
  • Use acetaminophen. Do not take pain relievers that contain aspirin and ibuprofen (Advil), it may lead to a greater tendency to bleed.
  • Get lots of rest, and drink plenty of liquids.
  • Avoid spreading the disease by preventing more mosquito bites.

Traveler Information

Clinician Information