Elizabeth Otero, M.D.

What is a Dust Mite?

House dust mite allergy is caused by mites living in the house dust and the allergy is actually brought on by the excrement of the mites. The house dust mites are co-inhabitants of our domestic environment and have nothing to do with inadequate hygiene. Neither do they carry any diseases. You will find a spectacular selection of mites in micro-photos. After dessication, the excremental capsules decay into very small particles and join up with the house dust. This allergy-containing dust can then be inhaled by breathing and lead to allergic complaints such as watering or itching of the eyes, coughing, congestion of the nasal mucosa, sneezing attacks, skin reactions and in serious cases to dyspnea and allergic asthma. If these symptoms occur all year round and if they are particularly severe in the evening or the early morning on rising, this would indicate a house dust mite allergy.

The two most common types of dust mite in our everyday environment are dermatophagoides pteronyssinus (Dust mite p) and dermatophagoides farinae (Dust mite f). The dust mites belong to the arachnid (spider) group. They feed mainly on human and animal skin scale and mold. A human being loses about one to two grams of skin scale every day, enough to feed 1.5 million house dust mites for a day. Apart from the availability of nourishment, the house dust mite population is encouraged by high atmospheric humidity.

The main reproductive period for house dust mites is in the months of May until October. At the beginning of the period when the heating is turned on and the consequent reduction in the atmospheric humidity the majority of the dust mites die off. At this time the maximum quantity of excrement has built up so this is also the time when the symptoms of those allergic to house dust mites are at their worst.