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July 2024 Newsletter

West Nile Virus Update

Red text says "Report Dead Birds" with a web address ( and phone number (1-877-968-2473) with an icon of a black bird upside down (dead). With the District website ( and logo in another box in the image

As of early July, a total of 5 dead birds collected in San Mateo County have tested positive for West Nile virus. Residents have reported over 220 birds so far this year, of which 65 were in appropriate condition for testing. Stay up-to-date with San Mateo County information HERE. Stay up-to-date with statewide information HERE.

No mosquitoes have tested positive for West Nile virus yet this year in San Mateo County. However, West Nile virus has been found in mosquitoes in other counties in Calfornia, so if you are traveling don't forget to take your mosquito repellent and follow other tips to prevent mosquito bites and the diseases they can spread.  Learn more HERE.

Mosquitofish Program Highlighted in Local Paper

Person in black hat and tan shirt holding up a clear plastic bag with water and small fish
Vector Control Technician Justin with a bag of mosquitofish ready for a resident's decorative fountain.

Our mosquitofish program was highlighted recently in The Almanac. Mosquitofish aggressively eat mosquito larvae and are a type of biological control of mosquitoes - using one living organism to control another organism.  They are a good long term, non-chemical solution for many types of large sources of standing water, like decorative fountains, backyard fishponds, and unused/green swimming pools. Learn more about how we use mosquitofish to control mosquito populations HERE (link will take you to the article in The Almanac).  If you are interested in whether mosquitofish are right for a water source on your property, please learn more HERE or reach out to us at 650-344-8592 to learn more!

2024 Open House

Our Open House was held on June 15. We had a great time showing attendees what we do! We hope to see you next year!

A child and adult examine something with a microscope and smartphones displayed on small stands.
A station to collect and view mosquito larvae under microscopes was very popular at the Open House!

CDC Issues Dengue Alert

Mosquito on a white background.  The mosquito has an abdomen full of dark red blood.  The mosquito is mainly black, with some white stripes on its legs.
Some types of Aedes mosquitoes can spread dengue virus.

You may have seen the recent news of CDC's health advisory regarding dengue virus risk. Our District actively monitors for many mosquito species, and San Mateo County does not currently have any of the mosquito species that can spread dengue virus. Staff also work with the San Mateo County Health Department to ensure that travel-acquired dengue cases do not lead to a local outbreak. If you are traveling, particularly internationally, please consider the CDC's recommendations for the public:

  • Learn how to prevent mosquito bites.
    • Use Environmental Protection Agency-approved repellents during travel to and after returning from areas with frequent or continuous dengue transmission.
    • Wear loose-fitting, long-sleeved pants and shirts.
  • Control mosquitoes at home indoors and outdoors.
    • Use air conditioning and window screens when possible, to lower risk for mosquito bites indoors.
    • Dump and drain containers that hold water to reduce mosquito egg-laying sites in your home and neighborhood.
  • Seek medical care if you have a fever or have dengue symptoms and live in or traveled to an area with dengue outbreaks.
  • If you plan international travel to a an area with frequent or continuous dengue transmission, protect yourself from mosquito bites during and after your trip.

Tick-bite Prevention Kits Now Available

Photograph of various papers with words including: tick-bite prevention, insect repellent, common ticks of California, tick-bite prevention kit. A pair of orange tweezers, a yellow device for removing ticks, and two packets of insect repellent wipes.
Tick-bite prevention kits include a variety of resources to help protect you from tick bites and the diseases they can transmit.

Do you live in San Mateo County? Do you spend time outdoors in natural areas? Would you like a no-cost tick bite prevention kit? Click HERE to learn more and request a kit.


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