If children catch viral infections early on, it could reduce their later risk of heart disease by as much as 90 percent. It is possible, therefore, that improved childhood hygiene could be one of the factors behind the explosion in coronary heart disease in the 20th century.
This marks the first time that the "hygiene hypothesis," which argues that reduced microbial exposure early on as a result of improved sanitation causes health problems later in life, has been connected with heart disease.
Some 350 patients with heart problems were compared with others who did not suffer from coronary disease. Each subject filled out a questionnaire about their childhood experience with such diseases as scarlet fever, measles and mononucleosis.
There was a consistent link between the number of childhood infections and reduced coronary risk. Two viral infections reduced risk by 40 percent, four infections by 60 percent, and six infections resulted in a 90 percent reduction in risk.
