Mosquito-Borne Disease Surveillance

Maricopa County Environmental Services Department has an extensive mosquito-trapping program that enables staff to identify areas where there is mosquito activity and to detect any mosquito-borne diseases. 

Various types of mosquito traps are set up throughout the county that collect mosquitoes for testing. These mosquitoes are pooled together, by species, into groups of 1-50 mosquitoes. This collection of mosquitoes is called a mosquito pool. The female mosquitoes are separated and are then processed and tested for West Nile virus (WNV) and Saint Louis Encephalitis (SLE). Traps with pools or samples that test positive for WNV and SLE are listed in graphics below.

West Nile Virus Statistics


Category
2010201120122013201420152016201720182019
 
2020
 
2021
 
2022
Positive Dead Birds0020000 0 1 0 0 0 00
Positive Horses0300310 0 2 1 1 4 00
Positive Mosquito Samples
186
9
168
139
218
97
95228138 417 10764
6238

Statistics provided by Environmental Services.

*Maricopa County Environmental Services Department's PCR testing results as of June 6, 2023.

St. Louis Encephalitis Statistics


Category
20152016 2017 2018 2019
 
 2020
 2021
2022
 
2023*
Positive Mosquito Samples600160106 213152442538
         


Statistics provided by Environmental Services.

* MCESD's PCR testing results as of June 6, 2023.

Public Health Statistics on Human Cases

Find current human case counts and historical case counts of mosquito-borne diseases among Maricopa County residents.

June 2023

Su M Tu W Th F Sa
28 29 30 31 1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 1

There are no published events in current month.

View All
  1. Environmental Services Department

    Physical Address
    301 W Jefferson St
    Suite 170
    Phoenix, AZ 85003

    Fax 602-506-5141

  1. Public Health


    Fax 602-506-6885