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

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

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.