Vector-Borne & Zoonotic Reports

  1. Mosquito-Related
  2. Rabies
  3. 5-Year Combined

The Maricopa County Department of Public Health (MCDPH), Office of Epidemiology, and the Maricopa County Department of Environmental Services (MCESD), Office of Vector Control, collaborate to educate and protect the residents of Maricopa County against mosquito-borne illness.

Mosquito-Borne Diseases in Maricopa County 2021

Case numbers are updated every Friday around 9 a.m. Due to the Thanksgiving holiday, case numbers are being updated early on Wednesday, November 24 and will resume regular updates on Friday, December 3.

Confirmed and Probable Cases & Deaths as of 11/23/2021

Locally Acquired

DiseaseCurrent Year CasesCurrent Year DeathsCases Same Date Last YearDeaths Same Date Last Year2020 Total Number of Cases
St. Louis Encephalitis (SLE)10626
West Nile Virus (WNV)*1,09179313
Unspecified Flavivirus (SLE/WNV)20202

*The number of WNV cases currently under review and pending classification is 381. This number is not reflected in the number of current cases above.


DiseaseCurrent Year CasesCurrent Year DeathsCases Same Date Last YearDeaths Same Date Last Year2020 Total Number of Cases

All data are provisional, based on date reported to Public Health.
Maricopa County weekly counts may vary slightly from state reporting due to differences in data reporting.

Current Year = 2021
Last Year = 2020

Disease Statistic Notes 

** Travel-related cases are those in which residents brought the disease in from other places or passed on the disease during birth as the result of infection acquired during travel.
† Unspecified Flavivirus indicates an infection that could not be attributed to a single mosquito-borne disease.

West Nile Virus End of Year Reports
The WNV end of year report provides information such as the annual number of WNV cases in Maricopa County, WNV activity by month, WNV rates per city, and number of mosquito pools by month.

Other Mosquito-Related Diseases
Other county reports for mosquito-borne illness are generated on an as needed basis.  

Mosquito-Borne Disease End of Year Reports
The end of year report provides information related to all local and travel-acquired mosquito-borne illness cases in Maricopa County. Data includes types/frequency of symptoms, locations of disease transmission, and characteristics of human infections. 
End of Year Final Report (PDF) 

Mosquito Sampling Statistics
Maricopa County Environmental Services Department (MCDES) Vector Control has an extensive mosquito trapping and testing program that enables staff to identify areas where there is a lot of mosquito activity and to detect mosquito-borne diseases. View the Mosquito-Borne Disease Statistics page for details.

 For more data not found here, you also can visit the ADHS Mosquito-Borne Illness page

  1. Office of Epidemiology & Data Services

    Physical Address
    4041 N Central Avenue
    Phoenix, AZ 85012

    Phone: 602-506-6900
    Fax: 602-372-8935
    Emergency: 602-506-6767