It seems that the current "allergy epidemic" is due not so much to an increase in allergenic risk factors as to the disappearance of factors protecting people against allergies.
The human immune system has not had the time to adapt to the rapid changes in the urban environment and way of life. These are the conclusions of Professor Tari Haahtela and his research team, who have been studying allergies in Finnish and Russian Karelia. Their project is part of the Academy's Microbes and Man Research Programme, the evaluation of which has just been completed.
The research was concerned with the prevalence of allergic diseases in Finnish and Russian Karelia as well as risk factors in schoolchildren and their mothers. The prevalence of atopic allergy was determined by skin prick tests and by measuring serum antibodies. Other data were collected by questionnaires.
In Finland, the risk of allergic predisposition in children is four times and in mothers 2.4 times greater than in Russia. There are also marked country differences in the prevalence of allergic diseases (asthma, allergic rhinitis and atopic eczema). Both in children and mothers their prevalence was significantly higher in Finland than in Russia. In an examination of generational differences it was found that children in Finland had more allergies than mothers, whereas in Russia the opposite was true. This suggests that the "allergy epidemic" in Finland is still ongoing, whereas in Russian Karelia it has hardly started.
Parental allergic disease was identified as a risk factor for allergies in children in both regions. Protective factors included farming as the family's main source of livelihood as well as having pets, especially in early childhood. In part these results lend support to earlier observations, in part they contradict them. An environment rich in microbes seems to generate widespread tolerance against various environmental allergens. In Russian Karelia, atopic allergy, an indirect indicator of westernization, has not increased during the past few generations.