| By Farah Chowdhry
‘Children who keep pets are healthier and more emotionally balanced' ( Daily mail )
Majority of youngsters regard their pet as a playmate and friend who can be a source of comfort when they feel sad. It has now been found that exposure to cats and dogs in the first year of life make them less likely to suffer from allergies. A recent report by experts at the Medical College of Georgia showed that children could 'significantly' reduce their risk of allergies by pet ownership. By the age of six, some children reduce their chances of getting hay fever or an allergic reaction to house dust mites by 75 per cent. This is an interesting fact as half of all allergy sufferers are children.
An allergy is an exaggerated immunological response to foreign substances in the environment leading to various types of acute or chronic inflammation. Recent studies suggest that microbial exposure as an infant might protect against asthma and might constitute a novel target for prevention. This is shown when children exposed to high levels of dust and microbial agents on living room floors were less commonly found to suffer from asthma.
Other studies on farmer's children have also reported a reduced risk of inhalant allergy (atopy), hay fever and asthma. However other studies in both rural and non-rural environments reported a significant inverse association between indoor endotoxin levels and atopic (hereditary) sensitization, hay fever, and atopic asthma. This might be because of exposure to a very high number of bacterial endotoxins which may cause a reaction to develop instead of atopic sensitization.
The mechanisms underlying these protective effects are not clear but might be related to an up regulation of T H 1 (T helper cells which are essential in controlling intracellular pathogens such as viruses and certain bacteria), and a down regulation of T H 2 (essential for antibody-mediated immunity as antibodies are needed to control extracellular pathogens) lymphocyte immunity.Alternatively, microbial exposure might enhance the activity of T regulatory cells ( T cells that act to suppress activation of the immune system ) resulting in a down regulation of both T H 2 and T H 1 immunity. However this mechanism is much to be desired and is still being investigated as it is not yet confirmed.
Another alternative study also found increasing evidence that environmental exposures determining childhood illnesses operate early in life. Prenatal exposure to a farming environment through the mother might also play an important role; as this may cause alteration in the innate (natural) immune system in offspring. The results of this study found that there was a dose-response relation between the extent of up regulation of these genes and the number of different farm animal species the mother had encountered in her pregnancy. This shows that maternal exposure to an environment rich in microbial compounds might protect against the development of allergies in infants.
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