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West Nile Virus Information

West Nile Virus (WNV) is a mosquito-borne virus that can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord). Only an estimated 1-3% of WNV infections, result in serious disease. Most people who are infected will show no symptoms at all, or have mild flu-like symptoms such as headache, fever and body aches. Rarely do symptoms get more severe.

WNV Cycle

WNV is spread by mosquitoes that feed on infected birds that have migrated into an area. The mosquitoes then bite people or horses, who may or may not become infected.

Encephalitis is not spread by person-to-person contact, nor animal to human contact. The cycle of WNV occurs at an unusually high intensity when there is both a large number of infected birds and a high rate of mosquitoes in a relatively small geographic area.

Bird Surveillance for WNV

Because WNV causes death in birds, we expect dead birds to be the first warning of WNV activity in an area. Since WNV is spread by mosquitoes feeding on infected birds, Maricopa County will be testing dead bird specimens for the presence of WNV.

MCESD will record and analyze dead bird reports, which will be used to identify areas for intensified surveillance of virus activity including bird testing, mosquito trapping and active disease surveillance.

If you should find a dead bird please report it to the MCESD Complaint Line at 602-506-6616 or file your complaint online at:
Dead Bird Complaint Form

Upon submitting a report, citizens will be advised of the delivery process.

Please note these guidelines
  • The bird must be freshly dead (less than 24 hours)

  • Not scavenged, no odor, no maggots, ants or other insects

  • Body must NOT be soft and mushy

  • Must NOT be a baby bird

  • Must NOT be a pigeon

  • Must NOT be a dove

  • Birds must be kept chilled.

  • Do not freeze. Freezing will kill the virus, if the virus is present.

  • When handling the bird, please use gloves or the inverted plastic bag method.

These reports will be summarized and provided to the state health department. See Arizona Department of Health Services for current statewide updates at:

Mosquito Activity

Mosquitoes are the known carriers (vectors) of the viruses from the host birds to humans. Humans and animals are incidental hosts in this bird-mosquito cycle.

If you are currently experiencing mosquito activity in your area, please report this activity to MCESD Complaint Line at 602-506-6616 or file your mosquito activity concern at:
Mosquito Complaint Form

The following are guidelines to minimize the risk of mosquito-borne illnesses:

  • Eliminate standing water, which allows mosquitoes to breed. Check for items outside the home that collect water, such as cans, bottles, jars, buckets, old tires, drums and other containers.

  • Change water in flower vases, bird baths, planters and animal watering pans at least twice a week.

  • Repair leaky pipes and outside faucets, and move air conditioner drain hoses frequently.

  • Avoid bites when going outside at night in areas where mosquitoes are present by using insect repellent.

  • Wear light-weight clothing that covers the arms and legs.

For more information on West Nile Virus:

See our mosquito fogging schedule for Maricopa County
Fogging Schedules

See the CDC website at:

Visit the Maricopa County Public Health website.