Science
Mosquito season is upon us. So why are Southern California officials releasing more of them?
Jennifer Castellon shook, tapped and blew on a box to shoo out more than 1,000 mosquitoes in a quiet, upscale Inland Empire neighborhood.
The insects had a job to do, and the pest scientist wanted every last one out.
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Their task? Find lady mosquitoes and mate.
But these were no ordinary mosquitoes. Technicians had zapped the insects, all males, with radiation in a nearby lab to make them sterile. If they achieve their amorous quest, there will be fewer baby mosquitoes than there would be if nature ran its course. That means fewer mouths to feed — mouths that thirst for human blood.
“I believe, fingers crossed, that we can drop the population size,” said Solomon Birhanie, scientific director for the West Valley Mosquito and Vector Control District, which released the mosquitoes in several San Bernardino County neighborhoods this month.
Sterilized male Aedes mosquitoes are released from a box in Rancho Cucamonga.
(Myung J. Chun / Los Angeles Times)
Controlling mosquitoes with mosquitoes
Mosquito control agencies in Southern California are desperate to tamp down an invasive mosquito — called Aedes aegypti — that has exploded in recent years. Itchy, unhappy residents are demanding it. And the mosquitoes known for fierce ankle biting aren’t just putting a damper on outdoor hangouts — they also spread disease.
The low-flying, day-biting mosquitoes can lay eggs in tiny water sources. A bottle cap is fair game. And they might lay a few, say, in a plant tray and others, perhaps, in a drain. Tackling the invaders isn’t easy when it can be hard to even locate all the reproduction spots. So public health agencies increasingly are trying to use the insects’ own biology against them by releasing sterilized males.
The West Valley district, which covers six cities in San Bernardino County, rolled out the first program of this kind in California last year. Now they’re expanding it. Next month, a vector district covering a large swath of Los Angeles County will launch its own pilot, followed by Orange County in the near future. Other districts are considering using the sterile insect technique, as the method is known, or watching early adopters closely.
On the plus side, it’s an approach that doesn’t rely on pesticides, which mosquitoes become resistant to, but it requires significant resources and triggers conspiracy theories.
“People are complaining that they can’t go into their backyard or barbecue in the summer,” Birhanie said at his Ontario lab. “So we needed something to strengthen our Aedes control.” Of particular concern is the Aedes aegypti, which love to bite people — often multiple times in rapid succession.
Releasing sterilized male insects to combat pests is a proven scientific technique, but using it to control invasive mosquitoes is relatively new.
Vector control experts often point to the success of a decades-long effort in California to fight Mediterranean fruit flies by dropping enormous quantities of sterile males from small planes. That program, run by the U.S. Department of Agriculture and the California Department of Food and Agriculture, costs about $16 million a year. That’s nearly four times West Valley’s annual budget.
So rather than try to tackle every nook and cranny of the district, encompassing roughly 650,000 residents, West Valley decided to use a more targeted approach. If a problem area reaches a certain threshold — over 50 mosquitoes counted in an overnight trap — it becomes a candidate.
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1. Solomon Birhanie inspects a container of mosquito larvae in the lab at the West Valley Mosquito and Vector Control District in Ontario. 2. Birhanie and his team raise mosquitoes in the lab, separating them by sex, because only the males, which don’t bite humans, will eventually be released. 3. Mosquito eggs in the West Valley lab. 4. The lab can grow about 10,000 mosquitoes at a time. 5. Before the male mosquitoes are released, an X-ray machine sterilizes them. If the zapped males mate with a female, her eggs won’t hatch. (Allen J. Schaben / Los Angeles Times)
And it’s still a big lift. About 10,000 mosquitoes are reared at a time at West Valley’s facility, about half of which will be males. The males are separated out, packed into cups and placed into an X-ray machine that looks like a small refrigerator. The sterilizing process isn’t that different from microwaving a frozen dinner. Zap them on a particular setting for four to five minutes and they’re good to go.
Equipment purchased for the program costs roughly $200,000, said Brian Reisinger, spokesperson for the district. He said it was too early to pin down a cost estimate for the program, which is expanding.
Some districts serving more people are going bigger.
The Greater Los Angeles County Vector Control District plans to unleash up to 60,000 mosquitoes a week in two neighborhoods in Sunland-Tujunga from mid-May through November.
With the sterile-insect program, “the biggest hurdle we’re up against really is scalability,” said Susanne Kluh, general manager of the L.A. County district, which is responsible for nearly 6 million residents across 36 cities.
In part to save money, Kluh’s district has partnered with the Orange County Mosquito and Vector Control District. They’re sharing equipment and collaborating on studies, but L.A. County’s releases will move forward first, said Brian Brannon, spokesperson for the O.C. district. Orange County expects to release its “ankle biter fighters,” as Brannon called them, in Mission Viejo this fall or next spring.
So far, the L.A. County district has shelled out about $255,000 for its pilot, while O.C. has spent around $160,000. It’s a relatively small portion of their annual budgets: L.A. at nearly $25 million and O.C. at $17 million. But the area they’re targeting is modest.
Mosquito control experts tout sterilization for being environmentally friendly because it doesn’t involve spraying chemicals, and it may have a longer-lasting effectiveness than pesticides. It can also be done now. Other methods involving genetically modified mosquitoes and ones infected with bacteria are stuck in an approval process that spans federal and state agencies. One technique, involving the bacteria Wolbachia was recently approved by the Environmental Protection Agency and is now heading to the California Department of Pesticide Regulation to review, said Jeremy Wittie, general manager for the Coachella Valley Mosquito and Vector Control District.
“Using pesticides or insecticides, resistance crops up very quickly,” said Nathan Grubaugh, associate professor of epidemiology at the Yale School of Public Health.
Vector control experts hope the fact that the sterilization technique doesn’t involve genetic modification will tamp down conspiracy theories that have cropped up around mosquito releases. One erroneous claim is that a Bill Gates-backed effort to release mosquitoes was tied to malaria cases in Florida and Texas. Reputable outlets debunked the conspiracy theory, pointing out that Gates’ foundation didn’t fund the Florida project and that the type of mosquito released (Aedes) does not transmit malaria.
To get ahead of concerns, districts carrying out the releases say they’ve engaged in extensive outreach and education campaigns. Residents’ desire to rid themselves of a scourge may overcome any anxieties.
“I think if you have the choice of getting eaten alive by ankle biters or having a DayGlo male X-rayed mosquito come by looking for a female to not have babies with, you’d probably go for the latter,” Brannon said. (“DayGlo” is a riff on the fluorescent pigment product of the same name — the sterilized mosquitoes were dusted with bright colors to help identify them.)
Sterilized male mosquitoes buzz around vector ecologist Jennifer Castellon as they are released in Rancho Cucamonga earlier this month.
(Myung J. Chun / Los Angeles Times)
Disease at our doorstep
As the climate warms and some regions become wetter, dengue is expanding to areas it’s never been seen before — and surging in areas where it’s established. Florida has seen alarming spikes in the viral infection in recent years, and Brazil and Puerto Rico are currently battling severe outbreaks. While most people infected with dengue have no symptoms, it can cause severe body aches and fever and, in rare cases, death. Its alias, “breakbone fever,” provides a grim glimpse into what it can feel like.
In October of last year, the city of Pasadena announced the Golden State’s first documented locally transmitted case of dengue, describing it as “extremely rare” in a news release. That same month, a second case was confirmed in Long Beach. Local transmission means the patient hadn’t traveled to a region where dengue is common; they may have been bitten by a mosquito carrying the disease in their own neighborhood.
Surging dengue abroad means there’s more opportunity for travelers to bring it home. However, Grubaugh said it doesn’t seem that California is imminently poised for a “Florida-like situation,” where there were nearly 1,000 cases in 2022, including 60 that were locally acquired. Southern California in particular lacks heavy rainfall that mosquitoes like, he said. But some vector experts believe more locally acquired cases are inevitable.
Ale Macias releases sterilized male mosquitoes in Upland this month.
(Myung J. Chun / Los Angeles Times)
Set them free
In mid-April, a caravan of staffers from the West Valley district traveled to five mosquito “hot spots” in Chino, Upland and Rancho Cucamonga — where data showed mosquito levels were particularly high — to release their first batches of sterilized male mosquitoes for the year. Peak Aedes season is months away, typically August to October in the district, and Birhanie said that’s the point. The goal is to force down the numbers to prevent an itchy tsunami later.
Males don’t bite, so the releases won’t lead to more inflamed welts. But residents might notice more insects in the air. Sterilized males released by West Valley will outnumber females in the wild by at least 100 to 1 to increase their chances of beating out unaltered males, spokeperson Reisinger said.
“They’re not going to be contributing to the biting pressure; they’re just going to be looking for love,” as Reisinger put it.
Eggs produced by a female after a romp with a sterile male don’t hatch. And female mosquitoes typically mate only once, meaning all her eggs are spoiled, so to speak. Vector experts say the process drives down the population over time.
Interestingly, the hot spots were fairly spread out across the district, indicative of the bloodsuckers’ widespread presence and adaptive nature. A picturesque foothills community in Upland was “especially interesting” because of its relatively high elevation, Birhanie said.
It was once inhabited primarily by another invasive mosquito that prefers colder, mountainous climates. Construction and deforestation in the area has literally paved the way for its humidity- and heat-loving brethren to move in.
Another neighborhood, in Rancho Cucamonga, posed a mystery. For the last two years, mosquito levels were consistently high. Door-to-door inspections, confoundingly, didn’t reveal the source.
“That’s one of the things about invasive Aedes mosquitoes — you can’t find them,” he said.
Next steps
Some vector control experts want to see a regional approach to sterile mosquito releases, similar to the state Medfly program.
Jason Farned, district manager for the San Gabriel Valley Mosquito and Vector Control District, believes a widespread effort “would be much more effective” and thinks that will come in time.
There are no talks underway to make it happen, and it’s not yet clear how it would work. Vector control agencies are set up to serve their local communities.
Fears of a bad mosquito year ahead are bubbling as the weather warms. Rain — which there was plenty of this spring — can quickly transform into real estate for mosquito reproduction.
When the swarms come, mosquito haters can take typical precautions: dump standing water and wear repellent. And they can root for the sterile males to get lucky.
Science
There were 13 full-service public health clinics in L.A. County. Now there are 6
Because of budget cuts, the Los Angeles County Department of Public Health has ended clinical services at seven of its public health clinic sites.
As of Feb. 27, the county is no longer providing services such as vaccinations, sexually transmitted infection testing and treatment, or tuberculosis diagnosis and specialty TB care at the affected locations, according to county officials and a department fact sheet.
The sites losing clinical services are Antelope Valley in Lancaster; the Center for Community Health (Leavy) in San Pedro, Curtis R. Tucker in Inglewood, Hollywood-Wilshire, Pomona, Dr. Ruth Temple in South Los Angeles, and Torrance. Services will continue to be provided by the six remaining public health clinics, and through nearby community clinics.
The changes are the result of about $50 million in funding losses, according to official county statements.
“That pushed us to make the very difficult decision to end clinical services at seven of our sites,” said Dr. Anish Mahajan, chief deputy director of the L.A. County Department of Public Health.
Mahajan said the department selected clinics with relatively lower patient volumes. Over the last month, he said, the department has sent letters to patients about the changes, and referred them to unaffected county clinics, nearby federally qualified health centers or other community providers. According to Mahajan, for tuberculosis patients, particularly those requiring directly observed therapy, public health nurses will continue visiting patients.
Public health clinics form part of the county’s healthcare safety net, serving low-income residents and those with limited access to care. Officials said that about half of the patients the county currently sees across its clinics are uninsured.
Mahajan noted that the clinics were established decades ago, before the Affordable Care Act expanded Medi-Cal coverage and increased the number of federally qualified health centers. He said that as more residents gained access to primary care, utilization at some county-run clinics declined.
“Now that we have a more sophisticated safety net, people often have another place to go for their full range of care,” he said.
Still, the closures have unsettled providers who work closely with local vulnerable populations.
“I hate to see any services that serve our at-risk and homeless community shut down,” said Mark Hood, chief executive of Union Rescue Mission in downtown Los Angeles. “There’s so much need out there, so it always is going to create hardship for the people that actually need the help the most.”
Union Rescue Mission does not receive government funding for its healthcare services, Hood said. The mission’s clinics are open not only to shelter guests, up to 1,000 people nightly, but also to people living on the streets who walk in seeking care.
Its dental clinic alone sees nearly 9,000 patients a year, Hood said.
“We haven’t seen it yet, but I expect in the coming days and weeks we’ll see more people coming through our doors looking for help,” he said. “They’re going to have to find help somewhere.” Hood said women experiencing homelessness are especially vulnerable when preventive care, including sexual and reproductive health services, becomes harder to access.
County officials said staffing impacts so far have been managed through reassignment rather than layoffs. Roughly 200 to 300 positions across the department have been eliminated amid funding cuts, officials said, though many were vacant. About 120 employees whose positions were affected have been reassigned; according to Mahajan, no one has been laid off.
The clinic closures come amid broader fiscal uncertainty. Mahajan said that due to the Trump administration’s “Big Beautiful Bill,” Los Angeles County could lose $2.4 billion over the next several years. That funding, he said, supports clinics, hospitals and community clinic partners now absorbing patients who previously went to the clinics that closed on Feb. 27.
In response, the L.A. County Board of Supervisors has backed a proposed half-cent sales tax measure that would generate hundreds of millions of dollars annually for healthcare and public health services. Voters are expected to consider the measure in June.
Science
Mobile clinic brings mammograms to women on Skid Row
Sharon Horton stepped through the door of a sky-blue mobile clinic and onto a Skid Row sidewalk. She wore a yellow knit beanie, gold hoop earrings and the relieved grin of a woman who has finally checked a mammogram off her to-do list.
It had been years since her last breast cancer screening procedure. This one, which took place in City of Hope’s Cancer Prevention and Screening mobile clinic, was faster and easier. The staff was kind. The machine that X-rayed her breast was more comfortable than the cold hard contraption she remembered.
Relatively speaking, of course — it was still a mammogram.
“It’s like, OK, let me go already!” Horton, 68, said with a laugh.
The clinic was parked on South San Pedro Street in front of Union Rescue Mission, the nonprofit shelter where Horton resides. Within a week, City of Hope, a cancer research hospital, would share the results with Horton and Dr. Mary Marfisee, the mission’s family medical services director. If the mammogram detected anything of concern, they’d map out a treatment plan from there.
Naureen Sayani, 47, a resident of Union Rescue Mission, left, discusses her medical history with Adriana Galindo, a medical assistant, before getting a mammogram on last week.
(Kayla Bartkowski / Los Angeles Times)
“It’s very important to take care of your health, and you need to get involved in everything that you can to make your life a better life,” said Horton, who is looking forward to a forthcoming move into Section 8 housing.
Horton was one of the first patients of a new women’s health initiative from UCLA’s Homeless Healthcare Collaborative at Union Rescue Mission. Staffed by third-year UCLA Medical School students and led by Marfisee, a UCLA assistant clinical professor of family medicine, the clinic treats mission residents as well as unhoused people living in the surrounding neighborhood.
The new cancer screening project arrives at a time of dire financial pressures on county public health services.
Citing rising costs and a $50-million reduction in federal, state and local grant and contract income, the Los Angeles County Department of Public Health on Feb. 27 ended services at seven of 13 public clinics that provide vaccines, tests and treatment for sexually transmitted diseases and other services to housed and unhoused county residents.
Although Union Rescue Mission’s own funding comes mainly from private sources and is less imperiled by public cuts, the 135-year-old shelter expects the need for its services to rise, Chief Executive Mark Hood said.
Even as unsheltered homelessness declined for the last two years across Los Angeles County, the unsheltered population on Skid Row — long seen as the epicenter of the region’s homelessness crisis — grew 9% in 2024, the most recent year for which census data are available.
For many local women navigating daily concerns over housing, food and personal safety, “their own health is not a priority,” Marfisee said.
Those whose problems have become too serious to ignore face daunting obstacles to care. Marfisee recalled one patient who came to her with a lump in her breast and no identification.
In order to get a mammogram, Marfisee explained, the woman first needed to obtain a birth certificate, and then a state-issued identification card. Then she needed to enroll in Medi-Cal. After that, clinic staff helped her find a primary care physician who could order the imaging test.
Given the barriers to preventative care, homeless women die from breast cancer at nearly twice the rate of securely housed women, a 2019 study found. Marfisee’s own survey of the mission’s female residents found that nearly 90% were not up to date on recommended cancer screenings like mammograms and pap smears, which detect early cervical cancer.
To address this gap, Marfisee — a dogged patient advocate — reached out to City of Hope. The Duarte-based research and treatment center unveiled in March 2024 its first mobile cancer screening clinic, a moving van-sized clinic on wheels that it deploys to food banks and health centers, as well as to companies offering free mammograms as an employee benefit.
“In true Dr. Mary fashion, she saw the vision,” said Jessica Thies, the mobile screening program’s regional nursing director. After working through some logistical hurdles, the mission and City of Hope secured a date for the van’s first visit.
The next challenge was getting the word out to patients. Marfisee and her students walked through the surrounding neighborhood, went cot to cot in the women’s dorm and held two informational sessions in December and January to answer patients’ questions.
At the sessions, the team walked through the basics of who should get a mammogram (women age 40 or older, those with a family history of breast cancer) and the procedure itself. (“Like a tortilla maker?” one woman asked skeptically after hearing a description of the mammography unit.)
The medical students were able to dispel rumors some women had heard: The test doesn’t damage breast tissue, nor do the X-rays increase cancer risk. Others questioned a mammogram’s value: What good was it knowing they had cancer if they couldn’t get follow-up care?
On this latter point, Marfisee is determined not to let patients fall through the cracks.
Thirteen patients received mammograms at the van’s first visit on Wednesday. Within a week, City of Hope will contact patients with their results and send them to Marfisee and her team. She is already mentally mapping the next steps should any patient have a situation that requires a biopsy or further imaging: working with their case manager at the mission, calling in favors, wrangling with any insurance the patient might have.
“It’ll be a good fight,” Marfisee said, as residents in the adjacent cafeteria carried trays of sloppy joes and burgers to their lunch tables. “But we’ll just keep asking for help and get it done.”
Science
Can fire-resistant homes be sexy? ‘You be the judge,’ says this Palisades architect
At first glance, it looks like nothing more than a charming Spanish-revival, quintessentially Californian home — but this Pacific Palisades rebuild is constructed like a tank.
Every exterior wall of the steel-framed home is a foot-thick, fire-resistant barricade. The home is connected to a satellite fire monitoring service. Should a fire start in town, sturdy metal shutters descend to cover every window. An exterior sprinkler system can pump 40,000 gallons of water from giant tanks hidden behind the shrubs in the property’s yard. If the cameras and heat sensors around the house detect danger, the system can envelop the home in over 1,000 gallons of fire retardant and hundreds of gallons of fire-suppressing foam.
Palisades resident and architect Ardie Tavangarian is so confident in his design that he even asked the fire department if they could start a controlled fire on the property to test it all out. (They said no.)
Tavangarian built a career designing multimillion-dollar luxury homes in Los Angeles, but after the Palisades fire destroyed 13 of his works — including his family’s home — he found another calling: how to design a house that can handle what the Santa Monica Mountains throw at it. And how to do it quickly and affordably.
Water tanks form part of a backup water supply in a newly built fire-resistant home in Pacific Palisades.
“Nature is so powerful,” he said, sitting on a couch in the new house, which he built for his adult twin daughters. “We are guests living in that environment and expecting, ‘Oh, nature is going to be really kind to me.’ No, it’s not. It does what it’s supposed to do.”
Tavangarian watched the Jan. 1 Lachman fire from his property not far from here; a week later that fire rekindled, grew into the Palisades fire, and burned through his house. But the painful details of the fire — the missteps of the fire department, the empty reservoir — didn’t matter when it came to deciding how to rebuild, he said. The reality is, many fires have burned in these mountains. Many more will.
A sprinkler on the roof is part of a house-wide sprinkler system.
For the architect, who has spent much of his 45-year career designing for luxury, hardening a home against wildfire has brought a new kind of luxury to his homes: peace of mind.
It’s a sentiment that resonates with fire survivors: Tavangarian says he’s received considerable interest from other property owners in the Palisades looking to rebuild their houses.
The metal shutters and advanced outdoor sprinkler system are the flashiest parts of Tavangarian’s home hardening project, and the efficacy of these adaptations is still up for debate. Because the measures have not yet been widely adopted, there are few studies exploring how much or little they protect homes in real-world fires.
Architect Ardie Tavangarian inside the house he designed.
Anecdotal evidence has indicated the effectiveness of sprinklers can vary significantly based on the setup and the conditions during the fire. Extreme wind, for example, can make them less effective. Lab studies have generally found shutters can reduce the risk of windows shattering.
These measures aren’t cheap, either. Sprinkler systems can cost north of $100,000, for example. However, Tavangarian said when all was said and done, the home he built for his daughters cost around $700 per square foot — less than what Palisades residents said they expected to pay, but more than what Altadena residents expected for their rebuilds.
Tavangarian also hopes to see insurers increasingly consider the home-hardening measures property owners take when writing policies, which he said could potentially offset the extra cost in a decade or less. As he explored getting insurance for the new home, one insurer quoted him $80,000 a year. After he convinced the company to visit the property, it lowered the quote to just $13,000, he said.
The house includes metal heat shields that can drop down if a fire approaches.
The home also has essentially all of the other less flashy — but much cheaper and well-proven — home hardening measures recommended by fire professionals: The underside of the roof’s overhang is closed off — a common place embers enter a home. The roof, where burning embers can accumulate, is made of fire-resistant material. The windows, vulnerable to shattering in extreme heat, are made of a toughened glass. There is virtually no vegetation within the first five feet of the home.
When asked if he felt he had compromised on design, comfort or aesthetics for the extra protection — one of the many concerns Californians have with the state’s draft “Zone Zero” requirements that may significantly limit vegetation within five feet of a home — Tavangarian simply said, “You be the judge.”
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