Study: Siblings, pets, farms help stop allergies

May 3, 2004

Last Updated: 2004-04-30 9:03:22 -0400 (Reuters Health)

LONDON (Reuters) - Having siblings, pets and living on a farm reduces

the risk of allergic illnesses in babies but having early infections

increases it, Danish researchers said Friday.

Sterile, modern environments have been blamed for the increase in

asthma, dermatitis and other allergic diseases over the past century

because the immune systems of babies are simply not exposed to many

microbes.

Scientists also thought that early infections would have a protective

effect against allergies but Stabell Benn, of the Danish

Epidemiological Science Center in Copenhagen, found they increase the

risk of developing allergies.

" We found that having older siblings protects against allergic diseases

but it is not by means of transferring infectious diseases because those

diseases are actually associated with an increased risk of disease in

the child, " Stabell Benn said in an interview.

" With each infection the risk (of an allergic illness) increases. "

The human immune system developed to deal with many different microbes.

Scientists believe that when it doesn't encounter them early in life, it

overreacts later and allergic diseases develop.

Pets, living on a farm, attending day care and having older siblings

increase a baby's exposure to microbes.

Benn and her team interviewed 24,000 women during pregnancy and when

their children were six and 18 months old. Their findings are reported

online by the British Medical Journal.

About 10 percent of the children suffered from dermatitis at 18 months

old. The researchers found that the risk of allergic illness increased

with each infectious disease the child suffered before six months old,

but it decreased if the child had three or more siblings, attended day

care or lived on a farm or with pets.

SOURCE: BMJ 2004.

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