California Launches Initiative Against Dengue Fever with Sterilized Mosquitoes

News Summary

California officials have initiated a project in Southern California aimed at reducing the invasive Aedes mosquito population, which is linked to the spread of dengue fever. By releasing sterile male mosquitoes, the project is designed to disrupt the breeding cycle and mitigate the risk of disease transmission. Initial results show significant reductions in mosquito populations, with plans for further releases in the coming years as the region grapples with the ongoing threat of dengue fever cases.

Los Angeles, California – A new initiative has been launched in Southern California to combat the rising threat of dengue fever, as officials turn to sterilized mosquitoes in an innovative effort to control invasive species linked to the spread of this potentially deadly disease.

Two vector control districts have initiated a campaign involving the release of thousands of sterile male mosquitoes in targeted neighborhoods. The West Valley District began this effort in 2023, while another district in Orange County is set to follow suit in 2024. The core objective of this initiative is to reduce the mosquito population by ensuring that eggs from females mating with these sterile males do not hatch, thereby interrupting the breeding cycle.

Only female Aedes mosquitoes bite and transmit diseases, including dengue fever, a viral illness that causes severe flu-like symptoms and can lead to hospitalization or even death. Hence, releasing sterile males is considered a safe and effective strategy to mitigate disease transmission risks.

In the Sunland-Tujunga area, one district reported an impressive 82% reduction in the invasive Aedes aegypti mosquito population where sterile males were released, compared to control regions. Meanwhile, another district in San Bernardino County saw a 44% decrease in mosquito populations in heavily infested areas after implementing similar sterile mosquito releases last year. Overall, the San Bernardino area has documented a 33% drop in invasive mosquito counts, marking the first reduction in eight years, a noteworthy achievement in controlling this growing public health threat.

The environmentally friendly approach does not involve chemical sprays and offers potential applications for addressing other disease-carrying mosquito species. However, challenges remain, including the scaling of the program to cover large populations and securing funding, which may necessitate increased property tax assessments.

The spread of Aedes mosquitoes in California has been exacerbated by climate change, which has extended the mosquito season, allowing these pests to thrive in new areas. With origins tracing back to Africa, Aedes aegypti mosquitoes not only carry dengue fever but also yellow fever, Zika, and chikungunya. Present in California for about a decade, they now inhabit over one-third of the state’s counties.

The life cycle of these mosquitoes complicates eradication efforts. A single female mosquito can lay eggs across multiple small water sources, making complete control difficult. Although sterilization techniques for pest control have been utilized since the 1950s, they are still relatively novel when applied specifically to invasive mosquito species.

Looking ahead, the West Valley District plans to expand its releases of sterilized males in 2024. The Orange County district expects to release between 100,000 and 200,000 sterile males weekly from late May through November. With a nearly $24 million budget, the Los Angeles County district is responsible for covering around six million residents across various cities, while the West Valley district caters to approximately 650,000 people, concentrating on areas with notably high mosquito numbers.

As dengue fever cases continue to emerge, California reported 18 locally acquired dengue cases in the previous year, predominantly in Los Angeles County, with outbreaks surfacing in cities such as Baldwin Park and Panorama City. Last year alone saw over 13 million dengue cases across the Americas, underscoring the escalating global threat posed by this disease.

To minimize the risk of mosquito-borne diseases, public health officials emphasize the importance of preventing mosquito bites through the use of repellents and eliminating standing water around homes. The California Department of Pesticide Regulation has approved the usage of mosquitoes infected with Wolbachia bacteria, which also contribute to preventing larvae from hatching.

Southern California’s novel approach to controlling invasive mosquitoes represents a pivotal step towards managing public health threats in the region, while also offering insights for future applications in combating other mosquito-borne diseases as climate change continues to advance.

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Additional Resources

• Los Angeles Times: Sterile Male Mosquitoes
• Wikipedia: Dengue Fever
• Vax Before Travel: Southern California’s Dengue Outbreak
• Google Search: Dengue fever California
• NBC Los Angeles: Locally Acquired Dengue Cases
• Encyclopedia Britannica: Aedes
• ABC7: LA County Dengue Fever Cluster
• Google News: California dengue cases
• LAist: California Dengue Cases Response
• Google Scholar: Dengue fever mapping