asthma

Chronic condition characterized by difficulty in breathing due to spasm of the bronchi (air passages) in the lungs. Attacks may be provoked by allergy, infection, and stress. The incidence of asthma may be increasing as a result of air pollution and occupational hazard. Treatment is with bronchodilators to relax the bronchial muscles and thereby ease the breathing, and in severe cases by inhaled steroids that reduce inflammation of the bronchi.

Extrinsic asthma, which is triggered by exposure to irritants such as pollen and dust, is more common in children and young adults. Less common, intrinsic asthma tends to start in the middle years.

Approximately 5–10% of children suffer from asthma, but about a third of these will show no symptoms after adolescence, while another 5–10% of people develop the condition as adults. Growing evidence that the immune system is involved in both forms of asthma has raised the possibility of a new approach to treatment.

Although the symptoms are similar to those of bronchial asthma, cardiac asthma is an unrelated condition and is a symptom of heart deterioration.

The National Medical Association estimated in 2005 that 17.6 million adults and nearly 5 million children suffered from asthma in the USA. In 1999 the incidence of death due to asthma in the USA was 5,000 per year. Research carried out in Denver, Colorado, indicated in 2000 that a new experimental drug could stop asthma attacks before they start and eliminate the need for other medicines in about half of the patients who took it.

In 1997 Brazilian researchers reported two species of dust mite actually living on children's scalps. This explains why vacuuming of bedding sometimes fails to prevent asthma attacks. The use of antidandruff shampoo should keep numbers of mites down by reducing their food supply.