Have you ever heard that households with at least one pet have children with fewer pet allergies? If so, think again. A recent study of 2,000 children has been released that contradicts these conclusions. This study's results suggest that the presence of cat allergens in the home is directly associated with an increased allergic sensitivity of children up to two years of age.

As children age, however, this seems to change. Children older than two years actually showed a decrease in allergen sensitization.

This research study showed that any contact with cat allergens increases allergic sensitization among young children. Consistent contact with cat hair, whether inside or outside the primary household, raises this risk. Their conclusions were based on detecting the presence of IgE-specific antibodies, which are produced in response to cat allergens.

These researchers used the data of the Lifestyle-Immune-System-Allergy (LISA) study. This LISA study investigated the effect that specific lifestyles had on the development of the immune system and allergic responses and diseases in childhood.

The children studied were born between 1997 and 1999. Their parents frequently answered questions about general family life and health, and they recorded the contact with pets. The study combines these responses with scientific analysis of a house dust sample, which was taken from each home three months after the birth of each child, to determine how allergic sensitization develops. This dust sample was analyzed to find cat allergens, and the results were compared to the IgE antibodies in the children's blood, which was tested at ages two years and six years.

In young children (up to age two years), the study showed a clear correlation between the cat allergens in the home and the incidence of allergic sensitization. Although this correlation decreased in the tests of six-year-old children, it was still noticeably present, which suggests that the risk was not completely eliminated.

The study demonstrated that the most important determinant of allergic sensitivity is family history: if the family has a high risk for allergies, the children will probably have a higher incidence of allergic sensitivity. Children are also likely to demonstrate the same diseases as their parents, like hay fever, asthma, or pet allergies.

Generally, the study concludes, families at high risk for allergies should not have cats in the household and should avoid them when possible. Because genetic risk plays a factor, however, even these behaviors will not protect children completely from allergic sensitization to cat allergens.