Allergies and the House Dust Mite

House Dust Mites and associated diseases

Exposure to house dust mites is recognised as a major cause of allergies worldwide. Common allergic diseases are asthma, rhinitis (hay fever), conjunctivitis and eczema. These allergies can all be associated with house dust mite exposure. Allergy symptoms can vary according to age, life style, environment and stress. Disease manifestations are as individual as the patients themselves.

Eczema is not always considered a true allergic reaction but it shares immune profiles with others and is considered part of the ‘classic’ allergy triangle of asthma, rhinitis, and eczema.

Allergies and asthmaA focus on eczema, often the first outward sign of an allergy problem.

In eczema emotional stress is known to be an important factor in prolonging the disease. If a flare-up of eczema is experienced without an obvious cause, bacterial infections on inflamed skin should be considered. If a bacterial infection has been found it often turns out to be Staphylococcus aureus. This bacteria may cause the weeping or crusting of diseased skin and has been known to lead to the chronic form of the disease. It is often referred to as the (golden bacteria) because of the colour of the product it produces.

Allergies and dust miteRecently, a large study on the risk factors for adults with allergies and in particular allergic eczema found dog dander to be the strongest, independent cause of the disease. The doctors were concerned that a patient with allergy to a family pet and suffering from eczema may be unaware of the cause of disease as the contact and eczema’s progress are mixed up and appear constant. The doctors also investigated inhaled risk factors for eczema in the indoor environment. They looked at house dust mites, animal dander (fine dust from skin and fur) and pollens and found all to be independently associated with the disease and considered all of them as risk factors. For patients, with allergic eczema, having more than one allergy increased the risks of exacerbation of symptoms. A cocktail of allergens, made worse by stress is most probably the underlying cause of allergic eczema in most adults.

Dust miteAdult house dust mites are so tiny they can sit on the tip of a pin. They have 8 legs and look a bit like a bag of clear jelly. An adult has a short life span of about 10 to 12 weeks. A healthy female can lay up to 3 eggs a day. After 6 to 12 days the egg will hatch producing a six-legged larva which will feed and then pass through 2 nymph stages before emerging as an adult.

House dust mites are scavengers that have lived on earth for 23 million years. They live in nest sites of warm blooded animals such as rats, birds, and humans. To help them survive they have evolved a clever way to recycle food. Mites use their droppings as a form of nourishment- and can eat them up to three times over.