Do kids get more allergies if the house is clean or dirty?
Does exposure to something increase or decrease the chance of an allergy in children? New study gives clues
It’s an ongoing debate for middle-class parents who have far more control over their environment than those with low incomes: does exposure to something increase or decrease the chance of an allergy in children?
In other words, does a spick and span house where no dog has dared to tread safeguard kids against a dog allergy? Or will this environment mean they develop an allergy when finally exposed to dogs because their immune systems have no experience of fighting back?The “hygiene hypothesis” suggests that underexposure doesn’t work in our favour and can increase allergies. But a new study has found that for vast numbers of children in Africa, particularly in low-income households, overexposure and other complicating factors have caused allergies to explode.
Just as worrying, according to the research, is that there are too few specialists to treat them, and the problem is also exacerbated by an increase in immune deficiency diseases.
Dr Elham Hossny, a professor of paediatrics and an author of the study by Ain Shams University in Egypt, said: “Across Africa, many communities are faced daily with sewage-contaminated water supplies, unsanitary living conditions and parasite infestations. But rather than strengthening their immune responses, as the hygiene hypothesis would suggest, allergic disease is on the rise.”Cape Town was suggested as one such site where this is the case, with Nairobi, urban areas of the Ivory Coast and other places where asthma rates are 18-20% which is “comparable to rates in the West”.
The hygiene hypothesis has also worked against Africa in terms of research. Because it was assumed that so much exposure reduced the risk, research has been focused elsewhere.
However, said Hossny, “people in Africa can be exposed to many risk factors that can trigger severe asthma and allergic reactions, including foods, animals and birds, house dust mites, mould spores, stinging insects and aero-allergens like smoke and pollen”.
Because it was assumed that allergy rates were low across the continent, “there is very little data showing just how big the problem is”.She said the study proved far more support is needed for increased data on the issue – especially since “the increase in diseases that compromise the immune system, such as HIV and primary immunodeficiency diseases [PIDs], is exacerbating the problem”.
The rate of new HIV infections in high-prevalence areas across Africa is high, and although only 2,500 patients have been diagnosed with PIDs, the number is estimated to be closer to a million.“We need to deliver a message to the policy makers in Africa and in everywhere in the world to help us promote our specialty and support our patients and perform the required research at a global standard,” said Hossny.
“In order for African allergists and immunologists to provide better care for their patients and to be able to perform cutting-edge research in the field, they need to be empowered by motivated governments, dedicated funds, and compassionate scientific partnerships.”
• The study was published in The Journal of Allergy and Clinical Immunology.