Mosquito Borne Illness

moquito horse bird personmoquito Images and sprayzika transmission cyclezika bug spray

Mosquito-borne diseases or mosquito-borne illnesses are diseases caused by bacteria, viruses or parasites transmitted by mosquitoes. They can transmit disease without being affected themselves. The Fresno County Department of Public Health and local Mosquito Abatement Districts: Consolidated Mosquito Abatement DistrictFresno Mosquito and Vector Control District, and Fresno Westside Mosquito Abatement District work in partnership with State and Federal agencies to protect our community from mosquitoes and mosquito-borne illnesses. Mosquito season in California usually starts in early March and ends late October when the weather starts to cool down. Click here for the Map of Mosquito Abatement Districts in Fresno County

Para más información sobre el Zika haga clic aquí: El virus del Zika | CDC

Para más información sobre el Nilo Occidental haga clic aquí: Nilo Occidental / CDC 
 What is Zika?

Zika is an infectious disease caused by the Zika virus, which is transmitted to people primarily by Aedes mosquitoes.  Symptoms of Zika typically include fever, rash, joint pain, and/or red eyes.

How do people get Zika virus?

Zika virus is primarily transmitted by Aedes aegypti mosquitoes (also known as yellow fever mosquitoes) and by Aedes albopictus mosquitoes (also known as Asian tiger mosquitoes). These mosquitoes are not native to California.  However, since 2011 they have been detected in several California counties. An Aedes mosquito can only transmit Zika virus after it bites a person who has this virus in their blood.  To date there has been no local mosquito-borne transmission of Zika in California. Thus far, Zika virus infections have been documented only in people who were infected while traveling outside the United States or through sexual contact with an infected traveler. Zika virus is not spread through casual contact such as touching, or hugging an infected person.

pregnant woman holding stomach

Zika and Pregnancy- The California Department of Public Health (CDPH) and the Centers for Disease Control and Prevention (CDC) recommend special travel precautions for pregnant women. Pregnant women in any trimester and women planning to become pregnant should consider postponing travel to areas where Zika virus transmission is ongoing.  

Pregnant women who must travel to one of these areas should talk to their healthcare provider first and strictly follow steps to avoid mosquito bites during the trip.

Zika Resources: 
Zika: The Basics of the Virus and How to Protect Against It   (En Español
Zika and Pregnancy: What you should know    (En Español)

West Nile Virus

West Nile Virus (WNV) is one group of disease-causing viruses that are spread by mosquitoes. Mosquitoes become infected with WNV when they feed on birds which carry the virus. The virus can then be transmitted to humans and other animals through the bite of an infected mosquito. Most people infected with WNV do not feel ill but some will experience mild flu-like symptoms. A smaller percentage of individuals develop serious complications. Hospitalization and even death can result from WNV infection.




Heard the Buzz? Brochure English(PDF, 17MB) | Español(PDF, 17MB) | Hmoob(PDF, 2MB)

 Zika Mosquito saying Heard the Buzz

West Nile Virus Education

West Nile Virus Resources 

To Report Dead Birds: Visit the California Department of Public Health website at or call 1-877-WNV-BIRD (877-968-2473) 

 Click here to submit an online report guidelines for Dead Bird Disposal

Aedes aegypti

Aedes Aegypti Mosquito

The yellow fever mosquito, Aedes aegypti, has been detected in Fresno County.

This mosquito is not native to California and is an efficient carrier of diseases such as dengueyellow feverchikungunya, and Zika.  Illnesses associated with this mosquito have not been reported.  Aedes aegypti is a small, dark mosquito with white markings and banded legs.  It may be active around dusk and dawn but bites most often during the day and often bites indoors. Fresno County residents are urged to call (559) 896-1085 to:

  • Report mosquito bites received during the day
  • Report mosquitoes which match the description above

Public Health Alert.pdf (English) Aviso de Salud Publica.pdf(PDF, 4MB)   

More information from California Department of Public Health  

More information from Centers for Disease Control and Prevention