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Science and Innovations

Scientists Investigate Link Between Hygiene And Asthma In Arizona Borderlands

University of Arizona Health Sciences

Mexican-American children north of the U.S.-Mexico border generally live in cleaner, healthier homes than those to the south. And yet, they have much higher rates of asthma. Scientists at the University of Arizona Health Sciences think exposure to some kinds of bacteria may be a good thing when it comes to asthma. They’re recruiting mothers and babies in Tucson and Nogales to test that idea, called “the hygiene hypothesis.” KNAU’s Melissa Sevigny spoke with Dr. Fernando Martinez about the study.

What made you interested in studying asthma in children in Nogales and Tucson?

There had been reports in the past of interesting relations between asthma rates, asthma prevalence, and the timing of the arrival of the United States of Mexican American children…. Those who were brought here to the United States when they were very young, meaning in the first years in life, have the same amount of asthma as their White, Caucasian, peers. But the older they arrived in the United States the less asthma they had…. And what we started finding out is that…there could be factors in Mexico that protect the children against the development of asthma. Together with that, a lot of data came out, the so-called “hygiene hypothesis,” which is the more exposed you are to protective bacteria in early life through farms and dogs and other children and going to daycare, the less asthma you’re going to have.

So some bacteria is actually good for you?

Yes…. Our hypothesis is that we have so much asthma today because we have become too aseptic. That’s the hypothesis. We don’t allow our children the first year of life to be exposed to the bacteria that would train their immune system, to understand what is good and what is evil out there…. It’s as necessary to encounter bacteria as it is to fall when you’re learning how to walk. There’s no life without risk. Eliminating risk has been very good because we have decreased infection, which is very important, but we’ve also decreased the positive influence of the good bacteria on the development of the immune system.

Now the study you’re starting right now, tell me more about how you’re setting that up.

The way we’re going to do it, we’re going to start during pregnancy, we’re going to contact mothers during their 28th week checkup, propose to study them and their children… and go to their homes and take samples of water and dust in their homes to see what inhabits in that dust and in that water, what kind of bacteria are there. And they’re we’re going to continue to following them, this dyad, as we call it, these two persons, mother and child, up to the age of two.

So you’re going to compare what you find with the mothers and children in Nogales to the mothers and children in Tucson?

Yes, exactly…. We’re going to really try to understand: what are the protective factors for these children in Nogales. And therefore, the ultimate goal is if we could develop therapies that imitate this protection, that’s what we aim at. You don’t need to be poor to be protected, is our motto. Perhaps there are ways in which we can imitate nature, imitate what is going on in Nogales, by developing drugs that are based on some of the bacteria and bacteria products that these children are exposed to.

Does it worry you in the past year there’s been a rise in sanitizing every surface?

I am extremely worried. As we say in Spanish, bread for today and famine for tomorrow. These kids are not exposed to anything right now…. It’s going to be very interesting, because this generation will be spared from infection at the very beginning, but may have a significant increase in chronic disease particularly asthma later in life.

Fernando Martinez, thank you so much for speaking with me.

Thank you very much.

Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.
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