Allergic disorders are common in children, and the prevalence of hay fever, allergic asthma, and atopic eczema has increased over the past few decades. Most of these disorders can be influenced by exposure to mite allergens. The best predictor for the development of asthma during childhood is allergic sensitization to mite allergens. More than one half of children who have atopic eczema are sensitized to mite allergens. Mite allergens have been shown to cause exacerbation of asthma and atopic dermatitis. Tsitoura and colleagues studied the effectiveness of prevention measures against dust-mite sensitization in children.

Toddlers and preschoolers who had at least one parent with atopic symptoms and sensitization were included in the study. In order to participate, children had to have no evidence of prior sensitization to mite allergens. The study was a multicenter, prospective, community-based, single-blind, randomized trial in Europe. Parents in both treatment groups received booklets on environmental influences on children's health and preventive recommendations. The intervention group also received information on methods to reduce mite exposure in the child's room, such as special dust mite–impermeable mattress covers, removal of carpeting in the child's bedroom, weekly laundering of bedding and soft toys in hot water, and other strategies. The use of a mattress covering was assessed during a home nurse visit or by a follow-up questionnaire at six months. Study participants were reassessed 12 months after the initial intervention. The main outcome measured was sensitization to mite allergens, as ascertained by skin-prick testing or specific immunoglobulin E testing and a questionnaire concerning atopic symptoms.

A total of 566 children participated in the trial and were available for follow-up at one year. The intervention group had a 3 percent incidence of sensitization to dust mite allergens, while the control group had a 6.5 percent incidence, a difference that was statistically significant. The control group had more allergic symptoms than the intervention group. In addition, physician diagnoses of asthma, eczema, and food allergies were higher in the control group.

The authors conclude that simple, harmless, and inexpensive measures can reduce sensitization to dust mites in toddlers and preschool-aged children whose parents have a history of atopic disorders. They state that it is important to determine whether prolonged avoidance of dust mite allergens can produce a sustained primary prevention of mite sensitization or secondary prevention in children who are already sensitized.

editor's note: The best preventive method for improving the health of patients is primary—preventing disease before it develops. Recent information has shown a substantial increase in the incidence of asthma and atopic disease. The goal for physicians is to try to prevent these diseases from developing in our patients. Tsitoura and colleagues have demonstrated easy techniques for reducing the exposure of children who are at risk for asthma or atopic disease. By establishing a parental history of atopic disease, physicians can implement this program with minimal expense to the parents and may prevent some of the adverse impact of atopic diseases on children.—K.E.M.