Fevers Associated With Lower Allergy Risk in Children
17, 2004 - NEWSdial.com)
Infants who experience fevers before their first birthday are
less likely to develop allergies by ages six or seven, according
to a new study funded by the National Institute of Allergy and
Infectious Diseases (NIAID), part of the National Institutes
of Health (NIH). The study, published today in the Journal of
Allergy and Clinical Immunology, lends support to the well-known "hygiene
hypothesis," which contends that early exposure to infections
might protect children against allergic diseases in later years.
"The prevalence of asthma and allergies has increased dramatically
worldwide in recent years," says Anthony S. Fauci, M.D., director
of NIAID. "This study provides evidence that diminished exposure
to early immunological challenges could be one of the reasons for
"The hygiene hypothesis is widely recognized but largely
unproven," says Kenneth Adams, Ph.D., who oversees asthma
research funded by NIAID. "The findings of this study strengthen
the hypothesis and, after more research, could lead to preventative
therapies for asthma and allergies."
The authors of the study followed the medical records of 835 children
from birth to age 1, documenting any fever-related episodes. Fever
was defined as a rectal temperature of 101 degrees Fahrenheit or
above. At age 6 to 7 years, more than half of the children were
evaluated for their sensitivity to common allergens, such as dust
mites, ragweed and cats.
Researchers found that, of the children who did not experience
a fever during their first year, 50.0 percent showed allergic sensitivity.
Of those who had one fever, 46.7 percent became allergy-prone.
The children who suffered two or more fevers in their infancy had
greater protection, with only 31.3 percent showing allergic sensitivity
by ages 6 to 7.
In particular, fever-inducing infections involving the eyes, ears,
nose or throat appeared to be associated with a lower risk of developing
allergies, compared with similar infections that did not result
"We didn't expect fever to relate with such a consistent
effect," says Christine C. Johnson, Ph.D, M.P.H., senior research
epidemiologist of the Henry Ford Health System in Detroit, MI,
and one of the co-authors of the study. "It also was interesting
that the more fevers an infant had, the less likely it was that
he or she would be sensitive to allergies."
says that more research is needed to establish if early fevers
have a direct
effect on allergic development in children.
Additionally, she and the other authors are working to determine
if early exposure to pets as well as high levels of bacteria could
also lower allergy risk. "If we can uncover which environmental
factors affect allergic development and why, it may be possible
to immunize children against these conditions," she says.
This study also received support from the National Institute of
Environmental Health Sciences, another NIH component.
Reference: L Keoki Williams et al. The relationship between early
fever and allergic sensitization at age 6 to 7 years. Journal of
Allergy and Clinical Immunology 113(2): 291-296 (2004).
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