Science
Immune amnesia: Why even mild measles infections can lead to serious disease later
Dr. Adam Ratner has heard a lot of myths and misunderstandings about measles in his decades as a New York City pediatric infectious disease specialist.
A troubling untruth he’s seen circulating on social media during the current outbreak is that being infected with the virus instead of getting vaccinated confers benefits on the immune system — a strength-training program of sorts for the cells.
The truth, Ratner said, “is exactly the opposite.”
Measles is a highly contagious virus that presents as a rash and cold-like symptoms for many patients, and can lead to serious or fatal complications for others. An outbreak that began in west Texas in January has since infected nearly 500 people across 19 states, including eight people in California.
An insidious but lesser-known consequence of even a mild measles infection is that it kills the very cells that remember which pathogens the patient has previously fought and how those battles were won. As a result, recurring bugs that might have caused only minor symptoms make patients as sick as if they’d never encountered them before.
Measles destroys lymphocytes that defend against other bugs to make way for ones that defend against measles, an immunity won at the cost of other protections.
This “immune amnesia,” physicians say, leaves patients vulnerable to reccurrences of diseases their immune cells were previously able to resist.
If a child gets sick with measles, “for the next two or three years, you kind of have to be looking over your kid’s shoulder, wondering if some otherwise routine virus or bacteria that they should be very well protected against is potentially going to land them in the hospital,” said Dr. Michael Mina, an epidemiologist who was previously an assistant professor of immunology and infectious diseases at Harvard Medical School.
“Even if your measles virus infection seemed mild and you kind of blew through it, it doesn’t mean that it was mild on your immune system,” Mina added.
Take rotavirus, Ratner said, which causes severe diarrhea that can be life-threatening for children if untreated. A child who has rotavirus once will have antibodies that offer protection against future infections.
But a measles infection, said Ratner, author of the recent book “Booster Shots: The Urgent Lessons of Measles and the Uncertain Future of Children’s Health,“ “could wipe out that immunity and they could be just as vulnerable to rotavirus as if they had never seen it before.”
Immune amnesia results from the measles virus’ plan of attack. Viral particles travel via airborne droplets of saliva, mucus and cells that make their way into a new body when their unsuspecting host breathes them in.
From there, they sneak past the protective barrier lining the respiratory system and head to the lymph nodes in search of cells that express a particular protein called signaling lymphocytic activation molecule, or SLAM.
The virus then rides around the bloodstream on these hijacked SLAM-expressing cells, further infecting and destroying other SLAM expressers it meets on the way.
Among the SLAM-expressing cells that measles wrecks are memory B and T cells, two crucial players in a functioning immune system. Memory B cells manufacture the right antibodies quickly when a familiar microbe appears. Memory T cells recognize and kill viruses that your cells have encountered in the past.
A measles infection feeds on these memory cells. Vaccines, in contrast, stimulate the production of memory B and T cells without consuming others in the process.
This was not yet understood in the decades before the measles, mumps and rubella vaccine’s approval in 1963, when measles was a common childhood disease that killed some 400 children in the U.S. each year.
“For 100 years or more, we’ve known that measles does cause an acute susceptibility to other infections,” Mina said.
A measles infection temporarily suppresses the immune system, Mina said, and it was long assumed that opportunistic infections around the time of the illness were the result of that short-term suppression.
In 2015, Mina and colleagues published a paper that looked at mortality data in the U.S., the United Kingdom and Denmark before and after measles vaccines were introduced. They found that whenever there were measles outbreaks, childhood deaths from all other infectious diseases remained significantly higher for two to three years in outbreak locations, an increase that accounted for up to half of all childhood deaths from infectious disease.
Once those countries rolled out the MMR vaccine, measles cases fell, as expected. But so did childhood deaths from other infectious diseases, by about half.
Three years later, Mina and his collaborators took blood samples from 77 unvaccinated children in a community in the Netherlands before and then two to six months after the children contracted measles. They found that the virus wiped out 11% to 73% of the children’s preexisting antibodies to a host of pathogens.
Just as children in preschool fall ill constantly with common diseases they’re encountering for the first time, unvaccinated children who contract measles are at higher risk in the ensuing years for common early childhood sicknesses such as respiratory infections, earaches and viruses that cause diarrhea, said Shelly Bolotin, a scientist at Public Health Ontario in Canada and director of the Center for Vaccine Preventable Diseases at the University of Toronto.
“In order to correct that depletion [of B and T cells], you need to be reexposed to everything you were immune to before, and this can take years,” she said.
As of late March, 97% of the people sickened in the current outbreak were unvaccinated or didn’t disclose their vaccine status. The measles virus is attenuated in the MMR vaccine, meaning that it has been altered to produce the appropriate immune response without triggering the disease itself. In the case of measles, that means no mass destruction of the cells that hold the immune system’s memory.
“It doesn’t have this very, very damaging effect, which is why we recommend vaccination, because we get all of the immunity with none of the adverse consequences,” Bolotin said.
Science
Owners of mobile home park destroyed in the Palisades fire say they’re finally clearing the debris
Former residents of the Palisades Bowl Mobile Home Estates, a roughly 170-unit mobile home park completely destroyed in the Palisades fire, received a notice Dec. 23 from park owners saying debris removal would start as early as Jan. 2.
The Bowl is the largest of only a handful of properties in the Palisades still littered with debris nearly a year after the fire. It’s left the Bowl’s former residents, who described the park as a “slice of paradise,” stuck in limbo.
The email notice, which was reviewed by The Times, instructed residents to remove any burnt cars from their lots as quickly as possible, since contractors cannot dispose of vehicles without possessing the title. It followed months of near silence from the owners.
“The day before Christmas Eve … it triggers everybody and throws everybody upside down,” said Jon Brown, who lived in the Bowl for 10 years and now helps lead the fight for the residents’ right to return home. “Am I liable if I can’t get this done right now? Between Christmas and New Year’s? It’s just the most obnoxious, disgusting behavior.”
Brown is not optimistic the owners will follow through. “They’ve said things like this before over the years with a bunch of different things,” he said, “and then they find some reason not to do it.”
Earlier this year, the Federal Emergency Management Agency denied requests from the city and the Bowl’s owners to include the park in the U.S. Army Corps of Engineers cleanup program, which FEMA said was focused on residential lots, not commercial properties. In a letter, FEMA argued it could not trust the owners of the Bowl to preserve the beachfront property as affordable housing.
A tattered flag waves in the wind at Asilomar View Park overlooking the Pacific Palisades Bowl Mobile Estates.
(Myung J. Chun/Los Angeles Times)
The Bowl, which began as a Methodist camp in the 1890s, was purchased by Edward Biggs, a Northern California real estate mogul, in 2005 and split between his first and second wives after his death in 2021. The family has a history of failing to perform routine maintenance and seeking to redevelop the park into a more lucrative resort community.
After FEMA’s rejection, the owners failed to meet the City of L.A.’s debris removal deadlines. In October, the city’s Board of Building and Safety Commissioners declared the park a public nuisance alongside seven other properties, giving the city the authority to complete the debris removal itself and charge the owners the bill.
But the city has yet to find funds to front the work, which is expected to cost millions.
On Dec. 10, City Councilmember Traci Park filed a motion that would order the city to come up with a cost estimate for debris removal and identify funding sources within the city. It would also instruct the city attorney’s office to explore using criminal prosecution to address the uncleared properties.
The Department of Building and Safety did not immediately respond to requests for comment.
Despite the recent movement on debris removal, residents of the Palisades Bowl still have a long road ahead.
On Wednesday, numerous burnt out vehicles still remained at the Pacific Palisades Bowl Mobile Estates. The owners instructed residents they must get them removed as quickly as possible.
(Myung J. Chun/Los Angeles Times)
In mobile home parks, tenants lease their spaces from the landowners but own the homes placed on the land. Before residents can start rebuilding, the Bowl’s owners need to replace or repair the foundations for the homes; fix any damage to the roads, utilities and retaining walls; and rebuild facilities like the community center and pool.
The owners have not responded to multiple requests for comment, but in February, Colby Biggs, Edward Biggs’ grandson, told CalMatters that “If we have to go invest $100 million to rebuild the park and we’re not able to recoup that in some fashion, then it’s not likely we will rebuild the park.”
Mobile home law experts and many residents doubt that the Biggs family would be able to convert the rent-controlled mobile home park into something else under existing law. The most realistic option, should the Biggs decide against rebuilding, would be to sell the park to another owner — or directly to the residents, a course of action the residents have been actively pursuing.
The lack of communication and action from the owners has nonetheless left the Bowl’s eclectic former community of artists, teachers, surfers, first responders and retirees in limbo.
Many are running out of insurance money for temporary housing and remain unsure whether they’ll ever be able to move back.
Science
Video: Drones Detect Virus in Whale Blow in the Arctic
new video loaded: Drones Detect Virus in Whale Blow in the Arctic
By Jamie Leventhal and Alexa Robles-Gil
January 2, 2026
Science
Commentary: ‘Stop exercising, you’re killing yourself.’ Not really, but try more nurture, less torture in 2026
One day my left foot hurt for no good reason. I stood up to shake off the pain and tweaked my right Achilles tendon, so I headed for the medicine cabinet, bent over like an ape because of a stiff back.
Actually, I lied.
It wasn’t one day. It’s pretty much every day.
None of this is severe or serious, and I’m not complaining at the age of 72. I’m just wondering.
Are my exercise routines, which were meant to keep me from falling apart, slowing my demise, or accelerating it?
What better time than the start of a new year to get an answer? In one poll, the top New Year’s resolution for 2026 is exercising more. Also among the top six resolutions are eating healthier, improving physical health and losing weight, so good luck to all you dreamers, and I hope you last longer than I have with similar resolutions.
Instead of a resolution, I have a goal, which is to find a sweet spot — if there is one — between exercise and pain.
Maybe I’m asking too much. I’ve had two partial knee replacements, I’ve got a torn posterior cruciate ligament, a scar tissue knob on a frayed Achilles tendon, a hideously pronated left foot, a right shoulder that feels like it needs an oil change, and a pacemaker that keeps on ticking.
But I decided to get some expert advice that might be useful for anyone who has entered this glorious phase of life in which it’s possible to pull a muscle while taking a nap, or pinch a nerve in your neck while brushing your teeth.
And I knew just whom to call.
Cedars-Sinai orthopedic surgeon Robert Klapper hosts an ESPN radio show called “Weekend Warrior.” This lab-coated Renaissance man, a surfer and sculptor in his spare time, also weighs in regularly on the radio with “Klapper Vision” — clear-eyed takes on all manner of twisted, pulled and broken body parts suffered by elite athletes and banged-up buzzards like me.
On “Weekend Warrior,” Klapper might be talking about knee replacement surgery one minute, segue to Michelangelo’s rendering of the human form, and then insist that a sandwich is not a sandwich without peperoncini. It isn’t necessarily all connected, but it doesn’t matter.
When I emailed Klapper about my aches and pains, he responded immediately to say he’s written one book on hips, another on knees and a third one is in the works with the following title:
“Stop Exercising, You’re Killing Yourself.”
No, he’s not saying you should never get off the sofa. In a phone conversation and later at his office, Klapper said the subtitle is going to be, “Let Me Explain.” He’s making a point about what kind of exercise is harmful and what kind is helpful, particularly for people in my age group.
Dr. Robert Klapper holds up his book about preventing hip surgery.
(Genaro Molina/Los Angeles Times)
My daily routine, I told him, involves a two-mile morning walk with my dog followed by 30 minutes of swimming laps or riding a stationary bike.
So far, so good.
But I also play pickleball twice a week.
“Listen, I make a living from pickleball now,” Klapper said. “Exercise is wonderful, but it comes in two flavors.”
One is nurturing, which he calls “agercise” for my demographic.
The other is abusive, and one of Klapper’s examples is pickleball. With all its starts and stops, twists and turns, reaches and lunges, pickleball is busting the Medicare bank, with a few hundred million dollars’ worth of injuries each year.
I know. The game looks pretty low key, although it was recently banned in Carmel-by-the-Sea because of all the racket. I had no idea, when I first picked up a paddle, that there’d be so much ice and ibuprofen involved, not to mention the killer stares from retirees itching for a chance to drill you in the sternum with a hot laser.
“This is a sport which has the adrenaline rushing in every 50-year-old, 60-year-old, 80-year-old,” Klapper told me in his office, which is the starting point in his joint replacement factory. The walls are covered with photos of star athletes and A-list Hollywood celebrities he’s operated on.
“I see these patients, but they’re not coming to me with acute injuries. They didn’t snap their Achilles tendon … like they do in tennis. They’re not snapping their ACL like they are in pickup basketball,” Klapper said. “They’re coming to me saying, ‘My shoulder is killing me, my knee is killing me.’ ”
Pickleball has obvious conditioning benefits for every age group. But it can also worsen arthritis and accelerate joint degeneration, Klapper said, particularly for addicts who play several times a week.
Not that he’s the first MD to suggest that as you age, walking, cycling and swimming are easier on your body than higher-impact activities. As one doctor said in an AARP article on joint care and the benefits of healthy eating, watching your weight and staying active, “the worst thing you can do with osteoarthritis after 50 is be sedentary.”
Still, I thought Klapper might tell me to stop pickling, but he didn’t.
“Pickleball is more than a sport to you … and all of your compadres,” he said. “It’s mental. You need it because of the stress. The world’s falling apart.… I want you to play it, but I want you to do the nurturing exercises so you can do the abuse.”
There’s no fountain of youth, Klapper said, but the closest thing is a swimming pool.
OK, but I already swim three times a week.
Dr. Robert Klapper meets with patient Kathleen Clark, who is recovering from knee surgery.
(Genaro Molina/Los Angeles Times)
Klapper had different ideas.
“You need to be walking forward and backwards for half an hour,” he said. Do that three times a week, he told me, and ride a stationary bike three times.
Why the water walking?
“We as humans take over a million steps a year. Forget pickleball, just in … daily living,” Klapper said, so I’m well beyond 72 million steps.
“Think about that,” he said.
Do I have to?
Water walking will develop muscles and joints without the stress of my full weight, and that could “optimize” my pickleball durability and general fitness, Klapper said. Buoyancy and the touch of water on skin are magic, he said, but there’s science involved too.
“It’s hard to move your arms and legs and your body through water, and yet it’s unloading the joint,” Klapper said. “And finally — and this is the real X factor — when you close your eyes and straighten your elbow and bend your elbow, straighten your knee and bend your knee … your brain knows where your limbs are in space.”
This is called proprioception, Klapper said. Receptors in your skin, muscles, ligaments and tendons send messages to your brain, leading to better balance, coordination and agility and potentially reducing risk of injury.
There are lots of exercises for sharpening proprioception, but the surfing doctor is partial to bodies of water. At my age, he said, my proprioception “batteries are running low,” but I can recharge them with a short break from pickleball and a focus on the pool.
“You can’t guarantee anything in life and medicine,” Klapper said. “But I guarantee you, a month into it, you’re going to feel so much better than you do at this moment.”
It’s worth a try, and I’ll let you know how it goes.
In the pool and on the court.
steve.lopez@latimes.com
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