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West Nile virus in Phoenix: Where mosquitoes have tested positive across Valley

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Posted at 1:41 PM, Jul 25, 2019
and last updated 2019-09-25 22:44:26-04

PHOENIX — As Maricopa County sees an early spike in West Nile cases among residents, ABC15 is looking at mosquito trap testing data that shows when and where county traps have had a positive test specifically for West Nile virus.

The first trap that returned a positive test this year for the West Nile virus was on March 20, and since then, a total of 415 mosquito trap tests have returned back positive for the virus. Officials say the Department of Environmental Services tests each of their 800+ traps every week.

Take a look at the heat map below to see where traps have returned positive West Nile virus tests so far in 2019.

The map shows an apparent hotspot located near Loop 101 and Loop 202 Red Mountain Freeway, which accounts for a trap located in that area. From April 11 to July 17, this individual trap has returned a positive West Nile virus test 13 times.

RELATED: West Nile virus human cases in Maricopa County continues to grow in 2019

Currently, it is unclear who maintains this trap, as county officials say it is under the jurisdiction of the Salt River Pima-Maricopa Indian Community, but officials with the SRPMIC tell ABC15 the trap is under the county's jurisdiction.

The Maricopa County Department of Environmental Services maintains over 800 mosquito traps across the county that are used to test mosquitoes for diseases and population counts.

This information helps officials determine where to schedule foggings to combat the mosquito population, as well as other preventative efforts.

The agency's interactive "Mosquito Management Map" shows where each county mosquito trap is located and where each fogging has taken place. To see when and where planned mosquito foggings will take place, check Maricopa County's fogging calendar.

If a trap meets any of the following four criteria, the test is determined to be "positive" and efforts are implemented, including fogging, according to officials:

  • A mosquito tests positive for carrying the West Nile virus
  • A mosquito tests positive for carrying St. Louis Encephalitis
  • 30 or more culex mosquitoes are found in a trap (culex mosquitoes are known carriers of West Nile virus)
  • 300 or more mosquitoes of any breed are found in a trap

To help prevent the growth of the mosquito population, officials recommend that residents stay aware of any water accumulation around their property and remove the stagnant water when possible.

RELATED: Mosquito birth control? University of Arizona researchers working to control dangerous insect population

If you want to prevent mosquito bites, officials recommend using the proper bug repellent, making sure to cover up with long sleeves and pants when possible, and installing proper screens to help prevent mosquitoes from entering your home.

For more information from the Maricopa County Department of Environmental Services on mosquitoes and mosquito control, visit its "Fight The Bite" website.

If you have a question or complaint about mosquitoes in your area, you can call the county's "Mosquito Hotline" at 602-506-0700.