It is a common notion that children should be kept in an environment as clean as possible to prevent them from contracting various kinds of infections. However, that much cleanliness may not turn out to be as good as we think for growing infants. According to some studies, some unclean conditions have been proved good for child’s developing immune system. Research shows that children who were kept in totally clean conditions have increased risk for developing infections like asthma, hay fever and other several infections. This is hygiene hypothesis.
What is Hygiene Hypothesis?
The term ‘hygiene hypothesis’ was first used by an epidemiology professor, David Strachan, in late 1980 s in British Medical Journal. Strachan in his study showed an inverse relationship between child’s risk of developing hay fever (allergic rhinitis) and number of older siblings in a family. His study showed that allergic diseases in young siblings were prevented by infection in childhood and transmitted via unhygienic contact from infected older siblings.
Other studies from different authors also supported the idea of hygiene hypothesis, early exposure to microbes during childhood protects against allergic rhinitis, asthma, and eczema. This hypothesis also explains food allergy and various autoimmune disorders such as Type 1 diabetes mellitus, multiple sclerosis, inflammatory bowel disease, cancer, and Alzheimer’s disease. Further studies show that children in developing countries are less likely to develop allergic rhinitis and asthma than those in developed countries of the world.
Before birth, babies who have low levels of immunity and protection against infection are provided by mother’s immunity in the form of antibodies. As they are born, antibodies from mother are no longer available so they have to fight against infections on their own. According to the U.S. Food and Drug Administration (FDA), child must be exposed to germs so that it has a chance to strengthen the developing immune system and produce antibodies to protect them.
In one research conducted by other scientists, microbial exposure triggers an internal inflammatory response in children raised in cleaner environments leading to diseases such as asthma and eczema. In late 1990s, various questions have been raised about the correlation between vaccines and hygiene hypothesis. However, studies conducted during that period hold that vaccination showed no correlation with children developing asthma and other diseases later in their lives.
Though there is a decreased risk of infection with some germs, there are many other microbes which put the child at risk of some dangerous conditions. Microbes - like RSV and Salmonella E.coli - produce many symptoms and make the child sick. So, in this context, cleaning is still important, though there should be a balance. The CDC recommends regular cleaning of house and disinfecting surfaces, especially when it has been infected. There are various other things that help in developing immune system. Progress in public hygiene has been achieved at the expense of protection against allergy in early childhood.