In 1897 Trouessart, a keen microscopist, discovered a mite new to science on a feather he was studying. The new mite was named Dermatophagoides pteronyssinus (comfortable in feathers). It was from a family of mites (Pyroglyphidae) the species of which are known to inhabit the nests of birds and mammals.

At the time the mite was considered rare and it was not seen again until 1928. Dekker (1 928) was amongst the first to suggest mites from this family living in house dust were a factor in respiratory allergies. Unfortunately, his findings remained largely ignored until Voarhorst et al (1964) suggested a link between allergy to house dust and an unspecified allergen produced by the house dust mite. It was not until the early 1 980’s that the allergen was identified and its presence within the mites’ faeces established.

An overwhelming weight of evidence suggests that childhood asthma is most frequently caused by primary sensitisation to the allergen in the faeces of the house dust mite Dermatophagoides pteronyssinus. Early infancy is the critical time in which primary sensitisation can occur and the period when infants are susceptible is relatively short, between 3 and 6 months after birth. Between 50 and 75% of atopic asthmatics give positive reactions to extracts of the allergen in house dust mite faeces. In this country there are an estimated 1 .3 million children suffering the debilitating symptoms of asthma, on average 1 52 are admitted to hospital every day.

A sharp increase in the incidents of mite allergic asthma has been seen in the past few decades. This correlates with a rise in domestic populations of house dust mites, principally in the bedroom; in mattresses, pillows, duvets / blankets and floor coverings. This rise has been caused by changes we have made to our indoor environment resulting in an increased indoor humidity.

Present asthma therapy relies on the administering of prescribed drugs. These drugs relieve the symptoms of asthma but do not tackle the cause. What is needed is a non drug based approach combining the initial removal of mites and their allergens from our homes and the creation of an indoor environment that is hostile to them.