West Nile Virus mosquito

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Photo credit: US CDC

About West Nile Virus

West Nile Virus (WNV) is a mosquito-borne viral illness. It occurs throughout the United States and can cause disease in humans, birds, and other mammals.

West Nile Virus spreads to a person through the bite of an infected mosquito. West Nile cases occur sporadically in Maine, usually during the summer and fall when mosquitoes in Maine are active.

West Nile Virus and Birds

West Nile Virus can infect certain kinds of birds and cause them to die. If you find three or more dead birds all at the same time in the same place, report these die offs to Maine CDC at 1-800-821-5821.


Most people infected with West Nile Virus do not develop any symptoms. However, signs and symptoms may develop. This usually occurs 3 to 15 days after being bitten by an infected mosquito, and include:

  • Fever and chills

    Fever and chills

  • Weakness


  • Headache


  • Body and muscle pain

    Body and muscle pain

More severe signs and symptoms may rarely develop. While severe illness can occur at any age, people over 60 years of age or people with certain medical conditions are at greater risk. Serious signs and symptoms include:

  • Inflammation of the brain

    Inflammation of the brain

  • Confusion


  • Neck stiffness

    Neck stiffness

  • Coma



Prevent Mosquito Bites

The best way to prevent mosquito-borne diseases is to prevent mosquito bites in the first place. Take these simple steps every day to prevent mosquito bites:

  • long pants

    Wear long-sleeved clothing and pants.

  • bug spray

    Use an EPA-approved bug spray.

  • trail

    Avoid outdoor activities from dusk to dawn, when mosquitoes are most active.

Protect Your Yard From Mosquitoes

You can make your yard a mosquito-safe zone:

  1. Empty sources of standing water around your home, including in man-made containers.
  2. Discard man-made containers around your yard that can hold water. If you cannot remove them, consider drilling holes in them to keep them from holding water.
  3. Put plant pots, yard toys, and other containers that hold water away or store-upside down to keep them from filling with water.
  4. Change the water at least once every week in containers that have to hold water, like birdbaths and pet water bowls. This makes sure that mosquito larvae (baby mosquitoes) cannot grow into adults.
  5. Check window and door screens for holes that mosquitoes can fly through and fix them.
mosquito property maintenance

To learn more about mosquito bite prevention and property management, visit Mosquito Frequently Asked Questions. Find more information about personal protection against mosquito bites here.

Resources for Educators

Maine CDC developed vectorborne school curricula for 3rd-8th grade classrooms. The curriculum is aligned with Maine Learning Results. School nurses, teachers, and other youth leaders are encouraged to use this resource in their classrooms.

Reports and Publications

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