Dengue-Infecting Mosquitoes in California
For years, Jason Farned and his crew at the San Gabriel Valley Mosquito and Vector Control District feared the arrival of dengue. This ruthless virus, common in tropical climates, has now grounded in America, California to be exact. A decade ago, Aedes mosquitoes—the species known to carry the virus—appeared in Los Angeles, presumably brought by global trade and enticing climate temptations.
California’s First Dengue Case
In October 2023, Pasadena Public Health Department sent an email. According to it, a Pasadena resident became the first Californian to contract dengue from a local mosquito. This marked an unsettling shift in reality for public health and pest control authorities in California. Aedes mosquitoes had introduced the previously foreign threat of dengue, chikungunya, Zika, and yellow fever to California’s residents.
Rise in Dengue Cases
Till now in 2024, authorities have identified 13 cases of locally acquired dengue, increasing from only two in 2023. Eleven in Los Angeles County and two in the San Diego area. These mosquitoes spread the disease by biting an infected person and then biting an uninfected one. Aedes mosquitoes, known for their fierce daytime biting, are now extensively present. They have spread in over 24 California counties, breeding in water as low as a capful.
Mosquito Surveillance and Control
To beat back dengue, California officials are expanding mosquito surveillance—developing detailed response plans for possible outbreaks and improving data sharing across agencies. Door-to-door campaigns are commissioned to remove stagnant water sources and apply pesticides. Residents are urged to wear bug repellents, long-sleeved clothes, and conduct mosquito control.
Besides, local agencies charged with managing disease-spreading insects are growing sterile mosquitoes themselves. They release these into the wild to lower local Aedes populations.
Dengue Outbreak and Symptoms
Locally acquired dengue cases have appeared in Arizona, Florida, Hawaii, and Texas, apart from California. Dengue is now endemic in Puerto Rico, leading to a public health emergency due to rising cases. With 12.3 million documented cases through August 2024, worldwide dengue cases are climbing, nearly doubling from 6.5 million in 2023.
Most people infected with dengue remain symptomless. One in four get sick and the symptoms are similar to the flu, passing within a week. But around 5% of dengue patients suffer significant illnesses—with potential internal bleeding, shock, organ failure, and even death. A second-time infection can increase risks further.
Developing a Dengue Vaccine
Unfortunately, no specific medication exists for treating dengue. The only FDA-approved vaccine is limited to specific conditions for children. The Takeda vaccine, developed by a Japanese pharmaceutical company, won approval in Europe and other regions but was withdrawn from the FDA due to data concerns. A Brazilian vaccine could receive future approval.
Mosquito and Dengue Control Plans
When a dengue case is detected, public health workers identify possible breeding spaces within 150 meters—the flight range of an Aedes mosquito. Ground teams go door to door, eliminating standing water, applying pesticides, and educating residents about dengue and preventive measures.
Public Health Education and Awareness
Outreach programs have been employed to educate the public about dengue. Emphasis is placed on wearing mosquito repellent, even after traveling to dengue-prone locations, to prevent the disease’s spread to local mosquitoes. Trust in public health authorities plays a significant role in making these efforts successful.
Controlling Mosquito Populations
Some counties with severe mosquito problems have engaged in aerial sprayings to curtail mosquito populations. Others are exploring drone technology for the same. But more than anything, the public needs to take the mosquito threat seriously and contribute to preventive efforts.
Ultimately, Jason Farned believes that this situation could serve as a wake-up call, urging everyone to work together and control this looming threat.