Children exposed to allergens and bacteria in their first year of life show decreased risk of developing allergies and asthma later in life, according to a new study published in the Journal of Allergy and Clinical Immunology on June 6.

Researchers investigated the homes of 467 newborn infants from Baltimore, Boston, New York and St. Louis to check the types and levels of allergens present in their environment. The health and development of these infants have been tracked since then.

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To the researchers' surprise, the findings suggest that infants who were exposed to less of the allergens and droppings of cat, roach and mouse dropping are less likely to develop allergies and respiratory problems in the future, WebMD has learned.

"What we found was somewhat surprising and somewhat contradictory to our original predictions," said Dr. Robert Wood, the study's co-author and chief of the John Hopkins Children's Center Division of Allergy and Immunology.

The study found that 41 percent of children who did not suffer from allergies and other respiratory ailments were found to have grown up in homes where bacteria and allergies were present. Only 8 percent of the children who were exposed to germs were reported to have suffered from allergies.

On the other hand, 51 percent of children who were not exposed to bacteria and germs were three times more susceptible to wheezing compared to 17 percent of children who lived in homes rich in bacteria and allergens.

Additionally, allergen and bacteria types and variety also played a role in helping the children develop immunity against the ailments. Infants who were exposed to a greater variety of bacteria were less likely to develop allergies by age 3.

"The combination of both - having the allergen exposure and the bacterial exposure - appeared to be the most protective," Wood said.

Allergist-immunologist in La Crosse, Wis. and American Academy of Pediatrics' Section on Allergy & Immunology Chair Dr. Todd Mahr points to the "hygiene hypothesis" to describe the results of the new study.

The hygiene hypothesis states that the natural development of a child's immune system is hindered by a lack of exposure to parasites and infectious agents, which generally leads to defects in immune tolerance, according to The Evolution & Medicine Review.

However, lead researchers Wood and Mahr stress that these are still preliminary findings and discouraging parents to react drastically such as getting a pet or conversely, getting rid of one.

A lot of other factors could have also contributed to the results of the study, citing exposure to tobacco smoke, household stress and possibly exposure to the same bacteria in the child's later years, they said.

TagsStudy, Science, scientific research, Robert Wood, Todd Mahr, American Academy of Pediatrics' Section, John Hopkins Children's Center, allergies, immune system, immunology, children's health, germs, bacteria, allergens, respiratory ailments, respiratory disease, asthma, exposure