September 23, 2005
‘Hygiene hypothesis’ Linked to Heart Disease Risk
By Matias A. Loewy
BUENOS AIRES (Reuters Health) - Early childhood viral infections might reduce the risk of developing heart disease later in life by as much as 90 percent, researchers from Sweden and Finland reported here on Wednesday at the IV World Congress of Pediatric Cardiology and Cardiac Surgery.
According to the investigators, "improved hygiene in early childhood might partially explain the greatest epidemic of the 20th century -- coronary heart disease."
It is the first time that the so-called "hygiene hypothesis" has been linked to the development of heart disease. The hypothesis proposes that reduced microbial exposure because of improved sanitation and cleaner lifestyles has facilitated the rise in asthma, allergic disease and multiple sclerosis in the Western world.
Researchers led by Dr. Erkki Pesonen, from the University Hospital in Lund, Sweden, compared 350 patients who had unstable angina or a heart attack with 350 subjects without coronary heart disease (control subjects). The study participants answered a questionnaire about their childhood experience with contagious diseases, specifically whether they had ever had chickenpox, scarlet fever, measles, German measles, mononucleosis, or infection of the parotid salivary glands.
Childhood contagious diseases were more frequent in the controls, researchers noted. Furthermore, they found a consistent trend between the number of childhood infections and the reduction in coronary risk. For instance, having two childhood viral infections reduced the coronary risk by 40 percent; four infections was associated with a 60-percent decreased risk; and six infections lowered the risk by 90 percent.
Dr. Horacio Faella, a pediatric cardiologist at the Garrahan Hospital, Buenos Aires, and member of the Organizing Committee of the meeting, considered these findings to be interesting but preliminary. "We need to do more studies about the influence of the immune system on the cardiovascular system," he said.