Mosquito-borne Diseases
Mosquitoes are arguably the most medically important group of insects. In addition to causing severe annoyance and allergic reaction, mosquitoes found in California are capable of spreading many diseases to humans and animals including:
- Chikungunya
- Dengue
- Filariasis (canine and feline heartworm)
- Malaria
- Saint Louis encephalitis (SLE)
- West Nile virus (WNV)
- Western Equine encephalitis (WEE)
- Yellow fever
- Zika
Historically, California has experience local transmission of malaria, western equine encephalomyelitis (WEE), St.Louis encephalitis (SLE), California encephalitis viruses, canine heartworm, and West Nile virus (WNV). Canine heartworm and West Nile virus continue to have frequent local transmission in California with West Nile virus human cases numbering in the hundreds every year. However, with increased global travel, the potential for the introduction or reintroduction of many mosquito-borne diseases into California still exists.
To learn more about mosquito-transmitted diseases, you can visit the website for the California Department of Public Health Vector-borne Disease Section. Learn more about how to protect yourself from mosquitoes and mosquito-borne diseases and how to prevent mosquito breeding on your property.
- Lyme disease
- Anaplasmosis
- Babesiosis
- Ehrlichiosis
- Rocky Mountain Spotted Fever
- Tick-Borne Relapsing Fever
To learn more about tick-transmitted diseases, you can visit the website for the California Department of Public Health Vector-borne Disease Section.

To learn more about rodent-transmitted diseases, you can visit the website for the California Department of Public Health Vector-borne Disease Section.
