Category: Healthy Living
The number of children suffering from allergies such as hayfever and asthma has risen across the world over the past decade, a study shows.
And the survey of about 500,000 children, aged between six and 14, found the increases were most common among the youngest.
In the UK, where about 1,700 children took part in the research, asthma cases went up from went up from 18.4 per cent to 20.9 per cent, hayfever from 9.8 per cent to 10.1 per cent, and eczema from 13 per cent to 16 per cent between 1991 and 2003.
Paediatrician Professor Innes Asher, of the University of Auckland, said: "The data have direct relevance for health service delivery in the countries included in the study as well as providing a basis for understanding these disorders.
The University of Auckland paediatrician added: "In almost all centres, there was a change in prevalence of one or more disorders over time."
Prof Asher and his colleagues found that increases in prevalence around the world were more common than decreases and occurred mostly among six and seven-year-olds.
The increases were greatest for eczema in the younger age group, and for hayfever in all children. But among 13 and 14-year-olds, where asthma rates had previously been high, symptoms of the breathing disorder more commonly decreased.
The only regions where increases in prevalence of all three disorders occurred more often among all the children were Asia-Pacific and India.
Prof Asher, whose findings are published in The Lancet, said: "Although changes in mean annual prevalence to the order of 0.5 per cent might sound small, such changes could have substantial pubic health implications, especially since the increases took place most commonly in heavily populated countries."
In 1991, researchers carried out the International Study of Asthma and Allergies in Childhood (ISAAC) to assess the worldwide prevalence of asthma, hayfever, and eczema.
Between 2002 and 2003, Prof Asher's team repeated ISAAC to examine any changes in prevalence. They surveyed the parents of more than 193,400 children aged six and seven from 37 countries on the presence of symptoms of asthma and allergies, such as wheezing, in their child.
They also asked about 304,680 children aged 13 and 14 from 56 countries the same questions. The study included developing countries such as South Africa, Brazil, and Iran as well as developed nations such as Canada, New Zealand, Sweden, and the UK.
Another study, also published in The Lancet, found children who become sensitive to allergens, such as cat hair, and suffer from wheezing in their first three years of life are more prone to developing asthma.
Between birth and school age some children who experience persistent wheezing lose their lung function and develop asthma but others do not.
The study of more than 1,300 German children found 90 per cent of those who experienced repeated wheezing but were not susceptible to allergies lost their symptoms at school age and retained normal lung function at puberty.
But the children who had repeated wheezing and developed sensitivity to allergens in their first three years of life were more likely to develop a loss of lung function and asthma. The researchers also found that exposure to high levels of allergens contributed to development of asthma.
Dr Dr Sabina Illi, of University Children's Hospital, Munich, said: "Given
the good prognosis for non atopic [non-allergy susceptible] wheezing children,
the need for these individuals to continue to take inhaled corticosteroids on a
regular basis should be re-assessed."
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