Q: Why are childhood allergies and asthma on the rise?
Over the last 50 years, the number of kids diagnosed with environmental allergies and asthma has been rising. In 2012, 10.6 percent of children (7.8 million individuals) reported respiratory allergies in the past 12 months. The fact that more children than ever are dealing with allergies is clear. Why this is happening is a tougher question and one doctors like myself discuss at every national allergy meeting.
The most popular theory right now is the “hygiene hypothesis.” This theory suggests that living in clean, urban environments, avoiding exposure to germs, and frequently treating infections with medications prevents kids’ immune systems from learning how to tell the difference between harmless and harmful irritants.
Multiple studies show that individuals who live on farms and have close contact with farm animals develop fewer allergic diseases. The thinking is that farm animals increase exposure to germs and germ components called endotoxins. When a person’s immune system responds to endotoxins early in life it’s less likely to react to allergens in the future.
Other studies have noted that increased antibiotic use has paralleled the rise in allergies. It may be that early antibiotic use changes the body’s bacterial flora, which impacts the development of allergic diseases such as asthma.
I anticipate that allergy doctors and researchers will continue to explore how exposure, or non-exposure, to germs and diseases in infancy can have a lifelong impact. We already know that early exposure to peanuts can help prevent peanut allergies, so preventing other diseases through exposure modification is a likely next step.
—By Gregory Owens, MD
Dr. Gregory Owens is an allergist and immunologist at Vancouver Clinic. He treats asthma, food allergies, seasonal allergies, and other conditions in adults and children.