Pets and Dirt Good for Child's Immune System
A feature story in the March
19, 2006 issue of USA TODAY reported that exposure to pets, peanuts and
intestinal worms might actually be good for children, because they program
their developing immune system to know the difference between real threats
and common exposures.
article begins by noting that this new thinking is opposite of the previous
conventional wisdom that said it was best to protect children from these
types of exposures. They now state just the opposite. Dr. Andy
Saxon of the University of California-Los Angeles, states, "What we've
learned is that it may, in fact, be important to be exposed early on to a
sufficient quantity of allergy-causing substances to train the immune system
that they are not a threat."
In the article Dr. Joel
Weinstock of Tufts New England Medical Center added, "When you're born, Day
Zero, your immune system is like a new computer. It's not programmed. You
have to add software. Between the ages of zero and 12, you're learning to
read, you're learning to write, and your immune system is learning to react
to things. Part of that is learning to limit reactivity."
The article explains the new
thinking on allergies by what is known as the "hygiene hypothesis". This
hypothesis suggests that growing up in cities and suburbs, away from fields
and farm animals, leaves people more susceptible to many immune disorders
such as allergies and asthma. To strengthen this point Dr. Weinstock
points to the difference between developed nations with urban communities
and undeveloped, countries, "Hay fever is the most common allergy in the
developed world," he says. "Yet, there are some countries in the world where
doctors don't know what hay fever is."
The article added further
evidence by reporting on a study by Dr. Dennis Ownby of the Medical College
of Georgia. In his study Ownby followed 474 infants in the Detroit
area from birth to age 7 at the Henry Ford Hospital in the hope of finding
clues to why some would pick up allergies and others would not. The
scientists on his team found that when they compared 184 children who were
exposed to two or more dogs or cats in their first year of life with 220
children who didn't have pets, the children raised with pets were 45% less
likely to test positive for allergies than other kids.
The article notes that this
new thinking could have a profound effect and help millions. They
report that more than 50 million people have allergic diseases, which are
the sixth-leading cause of chronic illness in the USA. Additionally,
they note that according to the National Institute of Allergy and Infectious
Diseases (NIAID), costing the health system $18 billion a year.