kottke.org posts about medicine
Thousands of people die every day from malaria, a disease that is transmitted to humans solely through mosquitoes. With CRISPR, scientists can easily genetically engineer mosquitoes incapable of transmitting malaria and using a technique called gene drive, they can force that genetic change into the native mosquito population. So, should we do it?
From the School of Public Health at Johns Hopkins comes this list of 100 things that have “made their mark on public health”, good and bad. Here’s a sampling of the objects:
Horseshoe crab. We all owe a debt of gratitude to the helmet-shaped horseshoe crab, whose ancestors date back 450 million years. From vaccines to needles to pacemakers, any IV drug or medical equipment that will come in contact with the human body must first be safety-checked using a test that comes from a clotting compound in the crab’s blood. This compound can detect even the smallest amount of deadly bacteria and is sensitive enough to isolate a threat equivalent to the size of a grain of sand in a swimming pool.
Vaccines. Immunization is one of the most important public health achievements in human history. Vaccines helped eradicate smallpox globally and eliminate polio in the United States. The introduction of effective vaccines has also drastically reduced deaths from measles, diphtheria, rubella, pertussis (“whooping cough”) and other diseases that sickened hundreds of thousands of Americans in the early 20th century.
American Cheese. Food processing was actually developed to make food safer. Milk is pasteurized to kill harmful organisms, and canning and freezing foods such as meats, fruits and vegetables helps them last longer. But the food industry has taken processing well beyond these early origins. Often, to extend a food’s shelf life, manufacturers increase fats, sugars, and salt and add in chemical flavorings, emulsifiers, and other additives — taking foods that could have been healthy and making them much less so.
Pap smear. Since its introduction in 1955, the Pap smear has reduced death from cervical cancer by more than 60 percent. Invented by Dr. Georgios Papanikolaou, the Pap smear is a diagnostic procedure in which a health-care professional swabs a cell sample from the cervix and sends it to a lab to see if any of the cells are malignant. Before the invention of the Pap smear, cervical cancer was one of the leading causes of death for women of childbearing age in the United States. Today, it comes in at number 14 on the list of cancers found in women.
Spittoons. Spittoons were developed centuries ago as receptacles for spitting — think ashtrays for saliva. These brass or even porcelain repositories were everywhere: In homes, train stations, saloons and even the U.S. Congress. They were meant for men to dispose their chewing tobacco and the abundant phlegm that accompanied the habit. Convenience turned to concern in the late 19th century when a global tuberculosis epidemic took hold and scientists realized that spittoons might actually spread diseases. Some argued that when people spat in the general direction of a spittoon and missed the target, they caused a greater health threat than if the spittoon hadn’t been there at all.
Vaccines. And now my kids don’t die.
James Hamblin, the dishy brainiac doctor who does those entertaining and informative videos for The Atlantic, is coming out with a book in December called If Our Bodies Could Talk. He calls it “a FAQ about human bodies”.
Now, in this original and entertaining book, Hamblin explores the stories behind health questions that never seem to go away — and which tend to be mischaracterized and oversimplified by marketing and news media. He covers topics such as sleep, aging, diet, and much more:
Can I “boost” my immune system?
Does caffeine make me live longer?
Do we still not know if cell phones cause cancer?
How much sleep do I actually need?
Is there any harm in taking a multivitamin?
Is life long enough?
Perfect eyesight. Curing cancer. Designer babies. Super-soldiers. Because of CRISPR, genetic engineering might make tinkering with life as easy as playing with Lego.
Imagine you were alive back in the 1980’s, and were told that computers would soon take over everything — from shopping, to dating, and the stock market, that billions of people would be connected via a kind of web, that you would own a handheld device orders of magnitudes more powerful than supercomputers.
It would seem absurd, but then all of it happened. Science fiction became our reality and we don’t even think about it. We’re at a similar point today with genetic engineering. So let’s talk about it.
Relatedly, I’m finishing up Neal Stephenson’s Seveneves right now and while it starts out as space science fiction, much of the book is concerned with the sort of genetic engineering issues discussed in the video.
After The Man freaked out back in the 60s, LSD and other psychedelics were banned and criminalized. But slowly, scientists are experimenting with psychedelics to treat depression, anxiety, and other ailments.
In the 1960s, a psychologist and former Harvard teacher named Timothy Leary coined the phrase ‘Turn on. Tune in. Drop out.’ The slogan was inspired by advertising jingles, but Leary wasn’t pushing a product, he was promoting a drug: LSD.
But today, scientists are studying psychedelics once again, in the latest twist in the long, strange story of LSD.
Even outside of a therapeutic setting, many people extolled the beneficial effects of psychedelics. Former Apple CEO Steve Jobs recalled in his biography by Walter Isaacson:
Taking LSD was a profound experience, one of the most important things in my life. LSD shows you that there’s another side to the coin, and you can’t remember it when it wears off, but you know it. It reinforced my sense of what was important — creating great things instead of making money, putting things back into the stream of history and of human consciousness as much as I could.
Check out the NY Times companion piece and the archival footage of LSD experiments on cats, spiders, and goats.
Errol Morris has made a short film about the world’s remaining stocks of smallpox virus 1 and the debate between those who want to eliminate the virus forever and those who want to keep it around.
In the story from classical Greece, Pandora was warned: Don’t open the box. She opens it anyway. The various pestilences are unleashed on the world but Hope remains at the very bottom of the box. Today there are microbiologists who want to continue to research smallpox. If they are given a free hand, what might they unleash?
There are those who insist that these residual stocks of smallpox should not be destroyed because some ruthless super-criminal or rogue government might be working on a new smallpox, even more virulent than existing strains of the virus. We may need existing stocks to produce new vaccines to counteract the new viruses. New viruses, new vaccines. New vaccines, new viruses. An escalating arms race with germs.
Keep this video in mind when you read about the latest advances with CRISPR.
The latest video from Kurzgesagt is an explainer on antibiotics and superbugs (drug resistant bacteria).
What would you say if we told you that humanity is currently making a collaborative effort to engineer the perfect superbug, a bug that could kill hundreds of millions of people?
Amos Dudley wanted to improve his smile but didn’t want to pay thousands of dollars for Invisalign, so he 3D printed his own orthodontic aligners.
I took a mold of my teeth with some cheap alginate powder, Permastone, and a 3d printed impression tray, to get a better picture of what was really going on. Notice LI-r (right lateral incisor) projected outward, and CI-r (right central incisor) depressed inward and overlapping.
At the time of writing this, I’m an undergrad, which means that a) I’m broke, and b) I have access to expensive digital fabrication tools - definitely an unusual dichotomy. I was researching [name brand clear-aligner treatment], and I ran across a photo that caught my eye.
Those look like the layer striations from a 3D print!
What is to stop someone, who has access to a 3D printer, from making their own orthodontic aligners?
Update: Unsurprisingly, orthodontists feel that DIY dentistry is not such a great idea.
Belli notes, “He moved these teeth in only 16 weeks. You can cause a lot of problems with that. If you move a tooth too fast, you can actually cause damage to the bone and gums. And if you don’t put the tooth in the right position, you could throw off your bite,” leading to additional damage and wear on the teeth.
John Hofsess helped eight people die and just before he died late last month at an assisted death facility in Switzerland, he wrote this piece.
I was horrified anew in 1999 when the gifted conductor Georg Tintner, who was dying from a rare form of melanoma, jumped from the balcony of his 11th-floor apartment in Halifax to end his agony. Many Canadians would hear such news, shake their heads, utter a few sympathetic platitudes and move on. But I couldn’t just sit back and wring my hands. That year, I went from advocating for assisted suicides to facilitating them. Let’s not mince words: I killed people who wanted to die.
On the most recent episode of Last Week Tonight, John Oliver argues against many US states’ anti-abortion laws. This was super funny and also made me really angry.
In an all-white room, mosquitoes are mated and the resulting larvae divided by sex. Workers whisk at stray mosquitoes with electrified tennis rackets — the kind you see in novelty stores, but which have sold out in mosquito-obsessed Brazil.
MIT Tech Review takes you inside the mosquito factory that could stop Zika and other diseases. (Add “working in a mosquito factory” to the list of jobs I’m glad I don’t have…)
For an episode called The Fix, Radiolab explores what anti-addiction drugs are available and why they aren’t more widely known and used to treat alcoholism and drug addiction.
Reporter Amy O’Leary was fed up with her ex-boyfriend’s hard-drinking, when she discovered a French doctor’s memoir titled The End of My Addiction. The fix that he proposed seemed too good to be true. But her phone call with the doctor left her, and us, even more intrigued. Could this malady — so often seen as moral and spiritual — really be beaten back with a pill?
We talk to addiction researcher Dr. Anna Rose Childress, addiction psychologist Dr. Mark Willenbring, journalist Gabrielle Glaser, The National Institute of Health’s Dr. Nora Volkow, and scores of people dealing with substance abuse as we try to figure out whether we’re in the midst of a sea change in how we think about addiction.
Neoantigen vaccines use the DNA from a cancer patient’s own tumor to, hopefully, eradicate the cancer.
For some 50 years, cancer biologists have tried to incite the immune system to attack cancer by targeting molecules that commonly stud the surfaces of malignant cells. These “antigens” act as homing beacons that immune cells find and lock onto (much as antigens on viruses attract the immune system, the basis for preventive vaccines such as that for measles).
Trouble is, normal cells sometimes sport the same antigens as tumors, and the immune system is programmed not to attack antigens found on healthy cells. As a result, revving up the immune system to target common tumor antigens hasn’t worked, leading to a number of failed experimental cancer vaccines.
That led biologists to a different approach: siccing the immune system on antigens found only on cancer cells — and only on the cancer cells of a single patient. “It’s highly unlikely that any two patients have the same neoantigens,” said Dr. Catherine Wu of Boston’s Dana-Farber Cancer Institute. “That’s why we have an opportunity to make cancer vaccines truly personalized, loaded with patient-specific neoantigens.”
Over the years, there’s been a growing consensus that suggests being happy is correlated with living a long life. Well, you can wipe that smile off your face because a massive study published in The Lancent makes it clear that no such correlation exists. So what about all those studies suggesting that stress and joylessness hastened death’s arrival? According the new study’s co-author:
In our view, the previous studies haven’t been well done. All that’s going on is ill health actually was causing unhappiness and stress.
In other words, your unhappiness is going to last longer than you thought.
Retro Report looks back on the story of the boy in the plastic bubble.
The epitaph on David Phillip Vetter’s gravestone observes correctly that “he never touched the world.” How could he have? From a few seconds after his birth until two weeks before his death at age 12, David lived life entirely in one plastic bubble or another. Touching the world would have killed him in fairly short order. Even his two weeks outside a plastic cocoon were spent in a hospital trying, futilely, to stave off the inevitable.
There was never a child quite like David Vetter. Americans above the age of, say, 45 may remember him not so much by name as by a phenomenon of the 1970s and early ’80s: “the boy in the bubble.” The Retro Report series of video documentaries, exploring major news developments of the past, returns to that era through interviews with, among others, David’s mother and one of his doctors. More than just a look backward, the report examines medical strides that now give hope to the once-hopeless, coupled with ethical questions long part of the “bubble boy” story.
I remember very clearly watching the news reports about “the boy in the bubble” when I was a kid. Now, as an adult and a parent, the ethical concerns hit me somewhat harder. (via @DavidGrann)
Today, the NY Times is running an editorial by Dr. Bennet Omalu called Don’t Let Kids Play Football. Omalu was the first to publish research on CTE in football players.
If a child who plays football is subjected to advanced radiological and neurocognitive studies during the season and several months after the season, there can be evidence of brain damage at the cellular level of brain functioning, even if there were no documented concussions or reported symptoms. If that child continues to play over many seasons, these cellular injuries accumulate to cause irreversible brain damage, which we know now by the name Chronic Traumatic Encephalopathy, or C.T.E., a disease that I first diagnosed in 2002.
Depending on the severity of the condition, the child now has a risk of manifesting symptoms of C.T.E. like major depression, memory loss, suicidal thought and actions, loss of intelligence as well as dementia later in life. C.T.E. has also been linked to drug and alcohol abuse as the child enters his 20s, 30s and 40s.
The story of Omalu, his research, and its suppression by the NFL is the subject of Concussion, a movie starring Will Smith that comes out on Christmas Day, as well as a book version written by Jeanne Marie Laskas.
But for the love of Julia Child and the sake of every other soul in the restaurant, particularly the underpaid line cooks sweating their way through another Saturday night shift, please, please stop describing your food preferences as an allergy.
Neil Swidey on why food allergy fakers need to stop.
In 1948, contact lenses were huge hunks of glass that don’t look at all comfortable. And the fittings started with a plaster cast of your eyeball. Ok, probably not plaster but still, ew. (via @FastidiumSum)
It’s getting more difficult for new painkilling drugs to be approved because the rate of effectiveness vs. placebos in drug tests is falling. But oddly, the drop is only being seen in the US.
Based on patients’ ratings of their pain, the effect of trialled drugs in relieving symptoms stayed the same over the 23-year period — but placebo responses rose. In 1996, patients in clinical trials reported that drugs relieved their pain by 27% more than did a placebo. But by 2013, that gap had slipped to just 9%. The phenomenon is driven by 35 US trials; among trials in Europe, Asia and elsewhere, there was no significant change in placebo responses. The analysis is in press in the journal Pain.
Concussion, starring Will Smith, is about Dr. Bennet Omalu, who discovered the link between football and CTE (Chronic Traumatic Encephalopathy) and will be out in December.
The movie is based on the 2009 GQ article, Game Brain.
Let’s say you run a multibillion-dollar football league. And let’s say the scientific community — starting with one young pathologist in Pittsburgh and growing into a chorus of neuroscientists across the country — comes to you and says concussions are making your players crazy, crazy enough to kill themselves, and here, in these slices of brain tissue, is the proof. Do you join these scientists and try to solve the problem, or do you use your power to discredit them?
Saw someone on Twitter saying that maybe this will be football’s The Insider. Let’s hope it moves the needle.
Update: From the NY Times, Sony Altered ‘Concussion’ Film to Prevent N.F.L. Protests, Emails Show.
In dozens of studio emails unearthed by hackers, Sony executives; the director, Peter Landesman; and representatives of Mr. Smith discussed how to avoid antagonizing the N.F.L. by altering the script and marketing the film more as a whistle-blower story, rather than a condemnation of football or the league.
“Will is not anti football (nor is the movie) and isn’t planning to be a spokesman for what football should be or shouldn’t be but rather is an actor taking on an exciting challenge,” Dwight Caines, the president of domestic marketing at Sony Pictures, wrote in an email on Aug. 6, 2014, to three top studio executives about how to position the movie. “We’ll develop messaging with the help of N.F.L. consultant to ensure that we are telling a dramatic story and not kicking the hornet’s nest.”
Matt Might, who is a professor in computer science at the University of Utah and a professor at the Harvard Medical School, responded to a question on Quora about minimizing the chances of having a disabled child and ended up answering two seemingly unrelated questions as well: How do you get tenure? and How do you live the good life? Long story short: he got tenure and started living the good life because he had a disabled child. But you should read the long story; it’s worth it.
My son forced me to systematically examine what matters in life — what really matters — and in the end, I came to appreciate a quote from his namesake, Bertrand Russell, more than I could have ever imagined:
“The good life is one inspired by love and guided by knowledge.”
My first year as a tenure-track professor cannot be described as anything other than an abject failure. I was so desperate to publish and raise funds that I began thin-slicing my research and submitting lots of poor quality papers and grant proposals.
I must have had a dozen rejections in a row that year. It sucked.
I remember huddling on the porch at the end of that year with my wife, telling her, “Well, I’ll at least have a job for six more years.”
I looked at my young son, cuddled in her arms. I saw his very existence hung in the balance between knowledge and ignorance.
Then it hit me: Life is too precious and too fleeting to waste my time on bullshit like tenure. I didn’t become a professor to get tenure. I became a professor to make the world better through science. From this day forward, I will spend my time on problems and solutions that will matter. I will make a difference.
I stopped working on problems for the sole purpose of notching up a publication. I shifted gears to cybersecurity. I found a project on cancer in the med school. I joined a project in chemical engineering using super-computing to fight global warming.
Suddenly, my papers started getting accepted.
You may remember Might and his son from a recent New Yorker article on people with ultra-rare diseases.
The Rosses were expecting twins but learned that one of the two, Thomas, wouldn’t live much past birth. They decided to donate Thomas’s body to science. And then, they decided to investigate just what it was they had given and how it had helped others. Great piece by Radiolab.
See also this piece in the Philadelphia Inquirer.
The next day, Gray met James Zieske, the institute’s senior scientist, who told her “infant eyes are worth their weight in gold,” because, being so young, they have great regenerative properties. Thomas’ corneas were used in a study that could one day help cure corneal blindness.
Thirteen more studies had cited that study. Gray felt a new emotion: pride.
A company called Oxitec has genetically modified mosquito eggs so that the mosquitos born from them pass along a gene to their offspring that prohibits the mosquitos from reaching sexual maturity and mating. They release the mosquitos into the wild, they mate with the local population of mosquitos, and those born from those matings will die before mating themselves. Voila! Pest control.
Oxitec has conducted trials with its modified mosquito in dengue-ridden regions of Panama, Brazil, Malaysia, and the Cayman Islands. The results show population suppression rates above 90 percent-far greater than the typical 30 percent achieved with insecticides.
The company is currently planning a trial in Florida using this technique to curb an influx of mosquito-borne illness.
Colorado has spent the last six years conducting a real life test to see if they could reduce the number of unwanted pregnancies and abortions. As the NYT’s Sabrina Tavernise explains, the results were stunning.
If we want to reduce poverty, one of the simplest, fastest and cheapest things we could do would be to make sure that as few people as possible become parents before they actually want to.
While reading this otherwise excellent article written by US soccer player Christie Rampone, I discovered a type of diet I’d never heard of before, the blood type diet (italics mine).
Age and parenting make me think about longevity. I definitely believe one big reason for my longevity has to do with the dietary and fitness changes I made after being diagnosed with auto-immune conditions after giving birth to my youngest daughter Reece in 2011. For example, I’ve gone gluten-free and have started to eat to my blood-type. Also, a friend introduced me to a natural ingredient called EpiCor to help strengthen my immune system. I have taken EpiCor daily for the past three years and it has become a beneficial part of my daily routine of rest, recovery, working out, eating healthy, and being in airports and hotels more than my own house.
From Wikipedia, an overview of the diet:
The underlying theory of blood type diets is that people with different blood types digest lectins differently, and that if people eat food that is not compatible with their blood type, they will experience many health problems. On the other hand, if a person eats food that is compatible, they will be healthier.
That theory is, in turn, based on an assumption that each blood type represents a different evolutionary heritage. “Based on the ‘Blood-Type’ diet theory, group O is considered the ancestral blood group in humans so their optimal diet should resemble the high animal protein diets typical of the hunter-gatherer era. In contrast, those with group A should thrive on a vegetarian diet as this blood group was believed to have evolved when humans settled down into agrarian societies. Following the same rationale, individuals with blood group B are considered to benefit from consumption of dairy products because this blood group was believed to originate in nomadic tribes. Finally, individuals with an AB blood group are believed to benefit from a diet that is intermediate to those proposed for group A and group B.”
As you might have already guessed, there is no evidence that eating your blood type is beneficial nor do the claims of differing lectin digestion have scientific merit. Homeopathic nonsense.
Sam Peterman is a sophomore in high school near Buffalo who runs track. She also has a condition called neurocardiogenic syncope (NCS) that causes her to faint after every race she runs, right into the waiting arms of her father soon after she crosses the finish line.
Dr. Blair Grubb, a professor at the University of Toledo who has studied syncope extensively, characterized NCS in a 2005 article in The New England Journal of Medicine as the autonomic nervous system’s failure to keep blood pressure high enough to maintain consciousness.
Physical activity, he said, pools blood in the lower half of the body, reducing blood flow to the heart. In response, the heart pumps more vigorously. In people with NCS, the brain misreads that as high blood pressure and tries to lower the pressure, which leads to decreased blood flow to the brain and, thus, fainting.
Peterman often does not remember the ends of races — she blacked out the last 60 meters of a recent race — which has prompted her father to wonder why she faints after races and not during. See also No pain, possible gain. (via @atul_gawande)
This is an interesting theory about the Harry Potter series: the whole thing is about a mentally ill young boy (Harry) who is institutionalized by his parents (the Dursleys) in a mental institution (Hogwarts) and the contents of the books are Harry’s fantasy.
In the Harry Potter series, his parents are famous wizards, who were famous in all the world for their unparalleled love for the boy Harry, which set the whole series in motion, killing them and leaving the boy a scarred orphan. (This is a fantasy, crafted as the direct opposite of the way in which children usually end up scarred — through abuse and neglect.)
If we interpret the story as Harry’s fantasy, then the Dursleys are Harry’s real parents, and the Potters are imaginary. The Durselys either can’t cope with the increasingly-delusional boy living with them, or perhaps they are merely abusive, and it’s the abuse that’s making him delusional. In any event, the parent-figures constantly mistreat him, favor the brother, and inflict endless cruelty and humiliation on him. One day, Harry snaps, and Dudley (who is really Harry’s brother) is severely injured, in a way requiring repeated hospital treatments. (In the delusion, Harry imagines that a pig’s tail is magically grown from Dudley’s buttocks.) As a result of this incident, Harry is taken away to a “special school.”
Oh, this sounds fantastic: PBS is set to air a six-hour documentary series, Cancer: The Emperor of All Maladies, starting at the end of March. How have I not heard about this before today?
This “biography” of cancer covers its first documented appearances thousands of years ago through the epic battles in the 20th century to cure, control and conquer it, to a radical new understanding of its essence. The series also features the current status of cancer knowledge and treatment — the dawn of an era in which cancer may become a chronic or curable illness rather than its historic death sentence in some forms.
The series is based on Siddhartha Mukherjee’s The Emperor of All Maladies: A Biography of Cancer, which is one of the most interesting books I’ve read in the past few years. Ken Burns is executive producing and Barak Goodman is directing.
Thanks to Sarah Klein at Redglass Pictures for letting me know about this. Redglass created a pair of videos for the series featuring Terrence Howard and Ken Jeong talking about their experiences with cancer.
Update: All three parts of the series are available on the PBS site for the next two weeks or so.
Two years ago, Angelina Jolie wrote in the NY Times1 about her choice to have a preventive double mastectomy. Today, she is back with an update on her choice to have another elective preventive surgery, the removal of her ovaries and fallopian tubes.
Two weeks ago I got a call from my doctor with blood-test results. “Your CA-125 is normal,” he said. I breathed a sigh of relief. That test measures the amount of the protein CA-125 in the blood, and is used to monitor ovarian cancer. I have it every year because of my family history.
But that wasn’t all. He went on. “There are a number of inflammatory markers that are elevated, and taken together they could be a sign of early cancer.” I took a pause. “CA-125 has a 50 to 75 percent chance of missing ovarian cancer at early stages,” he said. He wanted me to see the surgeon immediately to check my ovaries.
I went through what I imagine thousands of other women have felt. I told myself to stay calm, to be strong, and that I had no reason to think I wouldn’t live to see my children grow up and to meet my grandchildren.
I called my husband in France, who was on a plane within hours. The beautiful thing about such moments in life is that there is so much clarity. You know what you live for and what matters. It is polarizing, and it is peaceful.
The results of a major new trial, published in the New England Journal of Medicine, indicate that for children who are at risk of developing a peanut allergy, eating peanuts greatly reduces the chance of an allergy. This is pretty huge news.
All the babies were between 4 and 11 months old when they were enrolled, and all had either an egg allergy, severe eczema, or both-putting them at high risk of a peanut allergy down the road. Indeed, 98 of them were already heading in that direction: They tested positive for mild peanut sensitivity in a skin-prick test. This meant that these babies were already churning out antibodies to the peanut protein. Eating peanuts in the future could set off an allergic reaction.
The team divided the babies into two groups. Half were to avoid eating peanut products until they were 5 years old. The other half received at least 6 grams of peanut protein a week, spread across at least three meals, until they were 5 years old. Bamba was the preferred offering, though picky eaters who rejected it got smooth peanut butter.
Around the 5th birthdays of the trial subjects came the big test. The children consumed a larger peanut portion than they were used to in one sitting, and the results were clear-cut. Among 530 children who had had a negative skin-prick test when they were babies, 14% who avoided peanuts were allergic to them, compared with 2% of those who’d been eating them. In the even higher risk group, the children who were sensitized, 35% of the peanut-avoiders were allergic versus just over 10% of the peanut eaters.
Even if further studies confirm these results, will American parents start feeding their infants peanuts? I don’t know…there are lots of similarities to vaccines in play here.
Update: Somewhat related: children in developed countries might be growing up too clean, making them more likely to develop allergies.
The findings are the latest to support the “hygiene hypothesis,” a still-evolving proposition that’s been gaining momentum in recent years. The hypothesis basically suggests that people in developed countries are growing up way too clean because of a variety of trends, including the use of hand sanitizers and detergents, and spending too little time around animals.
As a result, children don’t tend to be exposed to as many bacteria and other microorganisms, and maybe that deprives their immune system of the chance to be trained to recognize microbial friend from foe.
That may make the immune system more likely to misfire and overreact in a way that leads to allergies, eczema and asthma, Hesselmar says.