Marnie Lowther has heard plenty of theories on why her son, Caleb, developed asthma at such an early age. “He was diagnosed at age 2, but he actually started showing symptoms like thrush, an oral yeast infection, at nine months,” says Lowther, 37, a Federal Aviation Administration budget analyst who lives in Columbia. “I was first told that it may have been triggered because he had contracted RSV [Respiratory Syncytial Virus, a lung infection that commonly afflicts children before their second birthday] when he was only two weeks old. But whenever we saw a different doctor, they all talked about other possible causes, like the fact we had dogs, or that maybe he picked up germs from his hospital visits, or at day care, which he started at eight months. I heard the whole gambit of different things.”
What was deemed the ultimate cause? He hadn’t developed the antibodies he needed to fend off illnesses.
Medical science has speculated for decades about the importance of antibodies, which regulate microbes (both good ones and bad) in everything from your gut (think: what you eat) and your environment (i.e. what you breathe), to breastmilk, and fluids in the birth canal (in a natural birth). But only in recent years has serious research been undertaken to unlock the complex secrets of how microbes help the body fight off diseases and allergies.
Just how important is antibody development at an early age? Answering that question was at the heart of recent groundbreaking research by Dr. Robert Wood, director of pediatric allergy and immunology at Johns Hopkins Children’s Center. His study went for the jugular of the so-called “hygiene hypothesis”—the media-darling theory that we’re all getting more illnesses because our houses are too clean. The research Wood and his collaborators in four cities conducted into the high rates of asthma in inner-city children inevitably addressed this central question: Why, if the hygiene hypothesis is true, are kids in cities with severe air pollution, cockroaches, and endless exposure to germy things still experiencing such high rates of asthma? Shouldn’t they instead have hardier immune systems?
The verdict: The hygiene hypothesis is true—but it’s just part of the story. Wood’s study data, published last year, contributed some fascinating scientific nuances to what we all hoped would be a nice, simple explanation.
The verdict: The hygiene hypothesis is true—but it’s just part of the story.
The NIH-funded study—conducted with partner institutions Columbia University Medical Center, Boston University School of Medicine, and Washington University in St. Louis—assessed 467 infants and confirmed that while children who live in inner-city homes do have higher overall allergy and asthma rates, those exposed to cat, mouse, and cockroach dander before their first birthdays seemed to benefit from that exposure, proving to be less likely to suffer from allergies and asthma. Further, the more bacteria, the healthier the kids were.
“It is likely that part, if not most, of the benefit of being exposed to mouse allergen, for example, is that mice leave a lot of debris in your home and that debris contains some healthy bacteria that may actually make your immune system stronger and less prone to develop asthma and allergies,” says Wood.
The benefit, however, has what you might call a Cinderella effect—the study found that those positive benefits stopped if the child was exposed after age 1.
But even the experts admit it’s complicated, and don’t want to imply everyone should roll their kids in horse manure and mouse droppings. “We can’t come back to the clinic and say that having a heavy infestation of cockroaches in your house is a good thing,” says Wood.
Bacteria, a type of microbe, are everywhere in our world and our person. We have them on our skin and inside our bodies. Our bacteria signature is so unique that some believe it has forensic capabilities that could be collected in crime-scene investigations, like DNA or fingerprints. In Western nations, the body’s microbial makeup—known as the microbiome—seems to be affected by hygiene. Simply sterilizing the water supply, for example, appears to be associated with the prevalence of food allergies. But there’s far more to the correlation between bacteria and human health than giving up hand sanitizer.