Helpful dust

Exposing babies to bacteria found in house dust could help prevent them developing allergies and asthma, researchers said. Scientists at the National Jewish Medical and Research Centre in Denver, Colorado believe a substance called endotoxin found in bacteria can enhance infants' immunity to asthma. ´´This potential allergy-protective effect of environmental endotoxin may help to explain why children growing up in rural settings in developing countries and on farms, close to animals, are less likely to develop allergies and asthma,'' Andrew Liu, who led the research team, said.

Liu and his associates tested their theory by measuring endotoxin in the homes of 61 babies who had symptoms of asthma. They also tested the babies for a range of allergies and measured their white blood cells to determine their immune response. Ten of the infants were allergic to at least one allergen such as milk, eggs, cats or dogs. When the researchers compared the levels of endotoxin in the babies' homes, they found them much lower in the homes of those with an allergy. In contrast, higher endotoxin levels corresponded with a raised immune response. Sterile modern lifestyles have been suspected as a cause of asthma, which is one of the world's fastest growing diseases, affecting an estimated 150 million people worldwide.

Experts are planning clinical trials of an inoculation which would expose newborn babies to bacteria with which they do not normally come into contact to try to build up their immune systems. Asthma sufferers' airways are sensitive to triggers such as colds, flu, cigarette smoke, pollen and animals. The irritation can mean that the airways are almost always inflamed. Although it cannot be cured, asthma can be treated with medication that calms the inflammation and relaxes the surrounding muscles.