In life, and many things that have to do with medicine, there is always a balance or as Eastern cultures describe “A Ying and Yang”. In modern times with all the social advancements and increase in medical knowledge there have been questions as to why we are seeing more allergies and asthma then generations that came before us. Many scientists are now investigating why we have seen a shift in the delicate balance of the way our bodies react to the environment as an explanation for why allergies and asthma may be increasing.
Many things are in delicate balance and it may be reasonable to ask which is better: Being dirty like pig pen in the Charlie Brown cartoon or being clean and carrying around hand sanitizer like it's a fashion accessory. On the surface it would seem that the cleaner the better.
As civilization evolved, we moved from the Cave Man to living in dirt floor huts with many family members in one space and farm animals living in close contact to the home, and then to overcrowded cities with poor sanitation practices. Many lives were lost to bacteria, viral, and parasitic type infections that spread like wildfire through the population. However, through natural selection and advancements in sanitation and health care, civilization survived. All the while our immune systems were watching and adapting.
As civilizations became more modern, sanitary practices improved and medicine advanced in leaps and bounds with vaccines, sterile hygiene practices, and antibiotics. Societies changed and families became smaller, living environments became cleaner and more sterile sanitary practice became more sophisticated. We also developed clean drinking water.
Despite the belief that no infection is better than having an infection, there are some studies that show that populations that are prone to particular types of infections like helminth/worms intestinal infections due to contaminated water are less likely to develop allergic asthma. Researchers are also investigating endotoxin, a component of Gram-negative bacteria to see how exposure to this substance could tip the scales of the immune response.
Children's environments also became very different as families that lived on farms very close to their animals and were exposed to all of the environmental allergens and irritants that one associates with a farming or agricultural society. Growing up in that type of environment created a very different set of exposures then one would see now growing up in a high-rise apartment in a big city or in a single-family home in suburbia.
So if we are cleaner and if we live smarter and if the advances of medicine have given us amazing vaccines to prevent disease what could possibly be bad about that? It is now thought that all these advances have changed many things that affect the delicate balance of our immune system. Since our immune systems are not being challenged as they once were because of cleaner living this has led to an imbalance between what immunologists call TH 1 and TH 2 immune response. This imbalance has perhaps caused an increase in allergic disease and asthma.
In brief, the so-called TH2 arm of our immune system is wired to deal with certain infections, like worms or parasites. Infants are born with their immune systems tilted toward TH2. After birth and on exposure to bacteria, viruses, etc. the immune system tilts back towards TH1 and comes into ‘balance’. In our cleaner world, however, this balance may be lost and those with a genetic predisposition who stay tilted toward TH2 are more prone to developing allergies and asthma. (For a more detailed explanation, click here)
Despite the belief that no infection is better than having an infection, there are some studies that show that populations that are prone to particular types of infections like helminth/worms intestinal infections due to contaminated water are less likely to develop allergic asthma. Researchers are also investigating endotoxin, a component of Gram-negative bacteria to see how exposure to this substance could tip the scales of the immune response. Studies from Europe have shown that children who go to daycare very early in life and are exposed to more children's more viruses /bacteria and potentially more infections tend to have fewer asthma and allergies as they grow up.
It is most likely not one single factor that has led to more asthma and allergy. Being a cleaner society (“the Hygiene hypothesis) has not been the only factor that altered our immune system. What it has shown, is that our life and health is a delicate balance and we need to learn from these changes to help us evaluate how they may contribute to the development of asthma and allergic disease.
Dr. Randy Stoloff
Allergy Partners of Fayetteville