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Vector-Borne Disease Activity in the County

The District monitors vector-borne disease activity - including West Nile Virus, dengue and flea-borne typhus - throughout the county and updates this page as necessary. 

West Nile Virus Activity

Map of West Nile Virus activity in Orange County, dated December 13, 2024, showing infections, mosquito samples, and dead birds.
* Most recent updated WNV activity map

 

WNV Data for 2023WNV Data for 2022WNV Data for 2021WNV Data for 2020WNV Data for 2019WNV Data for 2018WNV Data for 2017

 

Dengue Activity

Map of Orange County, CA showing travel-acquired dengue cases in 2024 by city, with color-coded case density. Total cases: 54.
* Most recent updated Travel Acquired Dengue cases map

 

Flea-Borne Typhus

Flea-borne typhus activity map in Orange County as of December 10, 2024, showing positive locations and total samples.
* Most recent updated flea-borne typhus activity map