Mosquito-borne Illnesses

Some mosquitoes carry diseases that infect people when they bite us. The diseases can vary by species – there are different kinds of mosquito – and by region.

In Contra Costa County, the only disease that mosquitoes are known to give humans is West Nile Virus.

The best way to avoid mosquito-borne illnesses is to avoid bites.

• Use insect repellant
• Cover up – wear long-sleeved shirts and pants, especially at dawn and dusk
• Use screens on windows or doors when it gets warm, or just use air conditioning

Contra Costa residents can also help to reduce the local mosquito population.

• Keep mosquitoes from breeding in your home or garden
• Report neglected (green) swimming pools, ponds or troughs of stagnant water
• Get help if you notice unusual mosquito activity

The Mosquito & Vector Control District offers free services and advice about mosquitoes at contracostamosquito.com or 925-771-6196.

Diseases

Dead Birds

Traveling

Resources

• Diseases

  Click these links for information from the Centers for Disease Control & Prevention (CDC) and the California Department of Public Health (CDPH) about mosquitoes and the diseases they carry in our state.

  • West Nile Virus | CDPH | CDC
  • Mosquito-Borne Encephalitis/Encephalomyelitis

  
  

  Follow these links for information about mosquito-borne illnesses that are catchable outside California.

  • Chikungunya (CDPH) | CDC
  • Dengue (CDPH) | CDC
  • Malaria (CDPH) | CDC
  • Rift Valley Fever (CDC)
  • Yellow Fever (CDPH) | CDC
  • Zika (CDPH) | CDC

  
  

• Dead Birds

  West Nile Virus, the only mosquito-borne disease in Contra Costa, often kills birds and squirrels when they are infected.

  If you notice a dead bird or squirrel, please call 1-877-968-2473 or use this web-based form to report it.

  Public health officials sometimes test the bodies of dead birds or squirrels for West Nile Virus, so we know where the disease is spreading. To learn more, visit westnile.ca.gov.

• Traveling

  Talk to your healthcare provider before taking a trip. There are medicines that reduce the chance of catching certain mosquito-borne diseases, and they are often recommended to international travelers.

  The Centers for Disease Control & Prevention (CDC) also offers current traveler health information and travel notices and alerts about diseases in the place you plan to visit.

• Resources

  Visit these pages to learn more about mosquito-borne disease.

  • Contra Costa Mosquito & Vector Control District
  • Mosquitoes and Mosquito-Borne Disease (CDPH)
  • Division of Vector-Borne Diseases (CDC)

  
  

  ArboNET, from the CDC and U.S. Geological Survey, is an interactive online map showing where mosquito-borne disease cases have been reported in the U.S.

  Articles and educational material:

  • Avoid Mosquito Bites
  • Avoid Bug Bites
  • Are you Raising Mosquitoes? – Home & Garden Checklist English | Spanish
  • Mosquito Bite Prevention – United States (CDC)
  • Mosquito Bite Prevention for Travelers (CDC)
  • Protect Your Family - Use a Repellent (CDPR) English | Spanish
  • Protecting Outdoor Workers English | Spanish
  • Podcast: West Nile Virus: Beware, It's Mosquito Season
  • Podcast: Dengue: Travel Safe
  • Podcast: Malaria: And Tropical Travel
  • Podcast: Malaria: Dangerous Creatures, A Visit to the CDC Insectary