Murray Valley encephalitis virus is spread to people through the bite of an infected mosquito.

Most people who get infected never have symptoms. Symptoms of Murray Valley encephalitis can include fever, headache, nausea, vomiting, and tiredness. Some people may develop severe symptoms including confusion, trouble speaking, and lack of coordination.

Travelers to Papua New Guinea, remote northwestern Australia, or southeastern Australia are at risk for being infected with Murray Valley encephalitis.

Activities that can increase a traveler’s chance of being infected include

• Spending a lot of time outdoors
• Traveling during times of the year when mosquitoes are more common, such as during the summer.

There are no vaccines or medicines that prevent Murray Valley encephalitis. Travelers can protect themselves by taking the following steps.

Use an EPA-registered insect repellent

• Use Environmental Protection Agency (EPA)-registered insect repellents with one of the active ingredients below. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women. If also using sunscreen, always apply insect repellent after sunscreen.
  • DEET
  • Picaridin (known as KBR 3023 and icaridin outside the US)
  • IR3535
  • Oil of lemon eucalyptus (OLE)
  • Para-menthane-diol (PMD)
  • 2-undecanone

Find the right insect repellent for you by using EPA's search tool.

• Insect Repellent Tips for Babies and Children
  • Dress your child in clothing that covers arms and legs.
  • Cover strollers and baby carriers with mosquito netting.
  • When using insect repellent on your child:
    • Always follow label instructions.
    • Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.
    • Do not apply insect repellent to a child’s hands, eyes, mouth, cuts, or irritated skin.
      • Adults: Spray insect repellent onto your hands and then apply to a child’s face.
    • If also using sunscreen, always apply insect repellent after sunscreen.

Wear long-sleeved shirts and long pants

Treat clothing and gear with permethrin

• Use 0.5% permethrin to treat clothing and gear (such as boots, pants, socks, and tents) or buy permethrin-treated clothing and gear.
  • Permethrin is an insecticide that kills or repels mosquitoes.
  • Permethrin-treated clothing provides protection after multiple washings.
  • Read product information to find out how long the protection will last.
• If treating items yourself, follow the product instructions.
• Do not use permethrin products directly on skin.
• Watch the CDC video How to Use Permethrin.

Keep mosquitoes out of your hotel room or lodging

• Choose a hotel or lodging with air conditioning or window and door screens.
• Use a mosquito net if you are unable to stay in a place with air conditioning or window and door screens or if you are sleeping outside.

Sleep under a mosquito net

• Sleep under a mosquito net if you are outside or when screened rooms are not available. Mosquitoes can live indoors and bite during the day and night.
• Buy a mosquito net at your local outdoor store or online before traveling overseas.
• Choose a mosquito net that is compact, white, rectangular, with 156 holes per square inch, and long enough to tuck under the mattress.
• Permethrin-treated mosquito nets provide more protection than untreated nets.
  • Permethrin is an insecticide that kills mosquitoes and other insects.
  • To determine if you can wash a treated mosquito net, follow the label instructions.

If you are bitten by mosquitoes, avoid scratching the bites and apply over-the-counter anti-itch or antihistamine cream to relieve itching.

If you traveled and feel sick, particularly if you have a fever, talk to a healthcare provider, and tell them about your travel. Avoid contact with other people while you are sick.