New tools urgently needed to protect Californians from mosquito-transmitted diseases

OPINION – Mosquito and vector control districts are on the front lines each day working to protect Californians from debilitating and deadly mosquito-transmitted diseases.

Invasive Aedes mosquitoes, which can transmit viruses that cause Zika, dengue, chikungunya, and yellow fever, pose significant challenges. First detected in California in 2013, these invasive mosquitoes are now in 25 counties throughout the state from San Diego to Shasta and are very hard to control. Districts urgently need new tools that can help them immediately fight back.

In the past 10 years, no new tools have been approved in our state to assist mosquito control districts in fighting the spread of invasive Aedes mosquitoes. Unfortunately, the California Department of Pesticide Regulation (DPR) is not demonstrating a sense of urgency to support research necessary to develop new tools to fight this difficult and expensive uphill battle. The timeframe it takes for disease-spreading mosquitoes to invade new regions is not in line with current regulatory standards for approval and such delays put our state very far behind.

While there has not yet been local transmission of Zika, dengue, chikungunya, and yellow fever in California, the question is not if, but when. Looking at last year alone, the border state of Sonora, Mexico had more than 9,000 cases with 91 people dying from dengue in 2022 and while 750 Floridians acquired dengue while traveling, 57 people were infected at home because the mosquitoes that can transmit the virus are in their neighborhoods.

Closer to California, in December 2022 in Maricopa County, Arizona two individuals tested positive for dengue that they acquired locally from being bitten by an infected mosquito. Without new tools, mosquito control districts in California will soon reach a tipping point and not be able to stop invasive Aedes from spreading deadly diseases, many of which have no cure or vaccine.

Part of the problem with controlling these invasive mosquitoes is that they need as little as a bottle cap of water to develop. They tend to lay their eggs in or around people’s homes, areas which are difficult for mosquito control professionals to inspect and treat. They are also becoming resistant to commonly used insecticides which makes control efforts even more challenging.

In addition, climate change has magnified the risks of invasive species and Aedes mosquitoes can now withstand temperate California winters, remaining a threat year after year. Excessive rainfall and prolific wildfires have also created attractive habitats for mosquitoes to develop.

Part of the problem with controlling these invasive mosquitoes is that they need as little as a bottle cap of water to develop.

It’s clear that relying on traditional mosquito control methods to control invasive mosquitoes is not enough. As we face new challenges we must stay ahead of the curve and ensure that mosquito control districts have as many tools as possible to protect public health.

Fortunately, there are innovative technologies available, but some are awaiting approval for pilot projects in California. Having the ability to study their effectiveness is a critical part in enabling mosquito professionals to make science-based and data driven decisions. As such, the Mosquito and Vector Control Association of California urges DPR to follow the science and approve research necessary to give mosquito control districts additional tools to protect public health and safety.

We cannot afford to wait any longer. As the pandemic taught us, protecting public health relies heavily on adequate preparation before it is too late to prevent the spread of deadly diseases.

Wakoli Wekesa, PhD, is president of the Mosquito and Vector Control Association of California and District Manager of the East Side Mosquito Abatement District