Mosquito & Vector-Borne Diseases

Even here in the dry climate of Maricopa County, mosquitoes are a problem. Mosquitoes are small insects that breed in standing water and the female mosquitoes need blood to lay eggs. Sometimes mosquitoes carry germs (e.g., viruses and parasites) that can be spread to a person when the mosquito bites them. Preventing mosquitoes from breeding and avoiding mosquito bites are the best ways to avoid getting these diseases.


Mosquito-Borne Diseases in Maricopa County 2017

Confirmed and Probable Cases as of 12/7/2017

DiseaseCurrent Year (2017) as of 12/7/2017Last Year (2016) as of 12/7/20162016 Total Number of Cases
St. Louis Encephalitis (SLE)300
West Nile Virus (WNV)926263
Unspecified Flavivirus (SLE/WNV)†100
Unspecified Flavivirus (Dengue/Zika)†244

All data are provisional, based on date reported to Public Health.

Disease Statistic Notes 

* To date, Maricopa County has only experienced travel-related cases of chikungunya, dengue and Zika, meaning that residents brought the disease in from other places.
† Unspecified Flavivirus indicates an infection that could not be attributed to a single mosquito-borne disease.

Weekly seasonal and annual summary numbers of mosquito-borne diseases, including the number of human deaths attributed to them, can be found here.

Additional mosquito-borne disease data  may be found on the ADHS Mosquito-Borne Disease webpage.