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Prevalence of Allergies Increasing Worldwide

A global study finds childhood allergies have increased in many countries over the last decade. The International Study of Asthma and Allergies in Childhood - known as ISAAC - includes data on two million school-aged children from 104 nations. Lead author Innes Asher - pediatric professor at the University of Auckland in New Zealand - says while researchers expected high rates of allergies in western countries, the report detailed some new trends elsewhere. "We saw rates in Latin America were also high. But at the same time, we have a lot of centers in the world where rates are very low by comparison, but [still] not negligible." She points to parts of India, Africa, parts of Asia and Eastern Europe, where rates are less than 5%.

Asher says one surprise is that rates for conditions like eczema - where skin becomes inflamed, red and itchy - are holding steady. "It implies that the whole human race doesn't have the potential to develop eczema. It doesn't go up to 100%. The high mark is 30 to 35 %."

Asher says some factors, like environmental toxins and pollutants, may weaken children's immune systems and allow allergies to develop, while others, like a healthier diet, could actually protect against such disorders. "Foods that had a plant origin like vegetables, nuts and cereals and rice were inversely related to rates of eczema and allergies," she says.

Asher says the ISAAC study is laying the groundwork for a global attack against these conditions. "[We're] looking at case controls of what is causing eczema and what isn't, and then leading to intervention studies. So, it does have the potential to lead to intervention studies which may be an intervention to prevent these conditions starting up in the first place."

ISAAC is in its 15th year. Innes Asher says one unintended consequence of this mammoth study has been to empower grassroots activists - armed with new data - to make their communities healthier places to live.

Research on the study is published in the British journal The Lancet.