Too much hygiene is harmful

The idea that a germless environment and an excessive hygiene do not necessarily lead to a decrease in infectious diseases is increasingly credited. At the AAAS meeting, held in Boston some days ago, Brett Finlay of the University of British Columbia, in Vancouver, provided evidences linking the rise of diseases such as asthma, eczema and type 1 diabetes (all of which seem associated with lower immune resistance) to an excessive improvement in hygiene. Finlay has focused on asthma and has reportedly concluded that it is caused by a lack of exposure to parasites and pathogens which, in fact, strengthen the immune system. Specifically, he has observed that children lacking certain bacteria – Faecalibacterium, Lachnospira, Rothia and Veillonella – in their bacterial flora are more likely to develop the condition. It has already been demonstrated that children raised in farms – environments with high levels of germs and bacteria – are less prone to develop asthma than city-raised ones. Additionally, statistics have shown that children born by Caesarean section develop a weaker immune system than those born by natural delivery, which immediately exposes the newborn to bacteria and pathogens.
(Source The Economist)