Hygiene Hypothesis

Many years ago, I came across a tale of The Wheezing Wolf and the Three Little Pigs , you could call it a breathless spin on a timeless children’s classic. It is also a tale that manages to very creatively highlight a disease state which affects a large number of children worldwide, specifically asthma. It is estimated more than 22 million people (~6 million children) in the United States have some form of asthma, a chronic but reversible condition which causes inflammation and bronchoconstriction of our airways.¹

Although there is no magic bullet or cure for people who suffer from asthma, we do have a large variety of medications that allow for proper management to help prevent long term airway remodeling, permanent lung damage, hospital stays and emergency room visits.¹ You might be wondering what causes people to acquire asthma. Data is gathered meticulously to better highlight trends in asthma for this very reason. For example, one trend already identified makes clear that African American and Hispanic children are generally more likely to experience mortality from asthma related causes.¹ Below you will find several interactable modules which outline the rise in asthma cases over time and the demographic aggregation of cases across the United States.

One theory which has gained traction over the years to explain rising cases of asthma is called the hygiene hypothesis. This hypothesis suggests our post natal immune response is compromised by an ultra clean environment.³ There is evidence to suggest lower levels of the bacterial protein lipopolysaccharide (LPS) in a person’s home would predispose them to develop conditions like asthma (LPS helps our immune system grow and learn by switching on toll-like receptor 4 (TLR4) on T-cells).³ If you would like to learn more about how this may relate to the COVID-19 pandemic, the following article is a nice read: The hygiene hypothesis, the COVID pandemic, and consequences for the human microbiome.

As a whole, asthma attacks can vary in severity and in nature from one person to another. Common triggers include tobacco smoke, dust mites, pollen, air pollution, mold, a man’s best friend, perfumes, harsh cleaners/disinfectants and even acid reflux.² It is important for patients who suffer from asthma to identify and avoid triggers. For example, encouraging tobacco cessation in households with smokers or using an air cleaner with a HEPA filter for people who may be allergic to their furry friends.²

Lastly, if there is one thing we know from the hygiene hypothesis, it’s that people love to clean their homes. It is especially true now perhaps more than ever before and we may very well see an even steeper rate of asthma cases moving forward, even if just from COVID sequelae alone. Here is a CDC guide for properly cleaning and disinfecting homes that patients (especially those sensitive to harsh detergents or cleaners) may find useful; it’s even COVID approved. 

References

1. U.S. Food and Drug Administration. Asthma Fact Sheet. Accessed May 2, 2021. Retrieved from https://www.fda.gov/consumers/minority-health-and-health-equity/asthma-fact-sheet.
2. Centers for Disease Control and Prevention. Common Asthma Triggers. Accessed May 2, 2021. Retrieved from https://www.cdc.gov/asthma/triggers.html.
3. U.S. Food and Drug Administration. Asthma: The Hygiene Hypothesis. Accessed May 2, 2021. Retrieved from https://www.fda.gov/vaccines-blood-biologics/consumers-biologics/asthma-hygiene-hypothesis.
4. National Center for Health Statistics, Centers for Disease Control and Prevention. Asthma Data Visualizations. Accessed May 2, 2021. https://www.cdc.gov/asthma/data-visualizations/default.htm.