The Germ Theory of Immunity

When kids get sick, parents can lose their minds.

When I was a kid we played in the dirt and endured all the usual childhood diseases. I see a lot of kids today who are not allowed to play outside and get dirty and they seem to be sick all the time. Is there any correlation?

Two studies (story here) came out recently that argued that farm kids have a lower risk of asthma than other kids because they are surrounded by more germs (viruses, bacteria, parasites), and their immune systems get a thorough workout before they ever get to school. This makes sense to me. Yet many urban and suburban parents take the opposite view. They don’t let their kids get dirty, they clean everything in sight and, they head to the doctor for antibiotics. Should they reconsider their approach, including those hand-held sanitizers and antibacterial wipes, which are more likely to produce resistant superbugs?

The consequences may be significant. There has been a massive increase in allergies diagnoses and a doubling of asthma diagnoses over the past 30 years. Arguably the air in cities has improved over those years because of the Clean Air Act, so could it be that childhood immunity has been compromised by not allowing children to fight off pathogens naturally? I mean, what is a fever for if not to kill off pathogens? There are other factors, of course: studies that show that children with older siblings often fight off diseases more quickly than single children and it does seem that obesity and lack of exercise also play a role.

The studies also raise the question of whether certain microbes are beneficial to the immune system. If researchers can identify them, could they help mitigate the effects of pathogens in children? Some researchers say that when measles vaccinations increased, it reduced immune responses in the respiratory tract and we saw an increase in asthma. That seems worth exploring. In the end, might it be that exposure to a broad range of germs is the best way to produce healthy kids?

Until then, the kids can be immunized AND they can play in the dirt.

Photo of E coli bacteria from Wikipedia - by Eric Erbe, digital colorization by Christopher Pooley, both of USDA, ARS, EMU.