Dust Mite Allergy – Allergies caused by Dust Mites
A dust mite allergy occurs as a reaction to nearly microscopic bugs that live in common house dust, mattresses, blankets and other fabrics. Dust mites live by eating tiny flakes of skin and pet dander, which comprise a large portion of house dust. Symptoms of dust mite allergies are commonly confused with other allergies, so dust mites are often overlooked as a cause. However, a campaign of dust mite awareness has begun in order to educate the public about this unseen danger.
What are Dust Mites?
Dust mites are arachnids and, as such, are closely related to spiders and ticks. They have eight legs and a two-part body consisting of a small cephalothorax and a much larger abdomen. The average dust mite is only 0.4 millimeters in length by 0.28 millimeters in width. Small to average-size dust mites are invisible to the naked eye, but large dust mites can be seen as tiny black specks, even though their true color is a creamy translucent blue. To positively identify dust mites, they have to be viewed through a minimum 10x magnification.
Dust mites feed on dead skin, which flakes off people and animals at a surprising rate. One study reported by the Boston Globe estimates that people lose from 30,000 to 40,000 skin cells per hour, which comes out to nearly one million per day. If you have pets, the number of dead skin cells in your home is even greater. These skin cells collect in the dust in your house, in your clothes, in the carpet, in your sheets and in your mattress, all of which are potential habitats for dust mites.
Although it sounds alarming, you probably have hundreds of thousands or even millions of dust mites in your home right now. They are very prolific little bugs, and they love warm, moist places such as mattresses and bed sheets in regular use. Experts estimate the average used mattress is home to somewhere between 100,000 and 10 million dust mites, and 100,000 dust mites can easily inhabit one square yard of carpet or rug.
A dust mite infestation can grow rapidly. Adult female dust mites lay up to 40 to 80 eggs at a time. The dust mites remain in their larval and nymph stages for the first month, and then they live as adults for one to three months. While their primary food is dead skin, they are not averse to eating small particles from pet food, cereal, breadcrumbs or other food. Food availability and moisture levels are the two greatest factors in dust mite proliferation.
Do Dust Mites Bite?
Dust mites can be a nuisance to some people, but most do not even notice them. Most people are completely unaware that they are probably surrounded by thousands of dust mites in their own home and the homes of their friends. Dust mites, themselves, are not dangerous. They do not bite people or pets. They bite only what they are going to eat. The problem some people have with dust mites is that they are allergic to dust mite wastes.
Like most members of the animal kingdom, dust mites have a digestive system to process food. What their body does not use is excreted. Dust mite excretions, sometimes called castings, build up in their habitat until they reach levels that can cause an allergic reaction in sensitive individuals.
The chemical that is responsible for causing the allergic reaction is a protein created inside the dust mite’s digestive system. The protein becomes mixed into the food matter during digestion and is excreted with the waste.
Who is Allergic to Dust Mites?
Anyone can potentially be allergic to dust mites, or more particularly, to dust mite castings. Medical scientists believe certain people are genetically predisposed to have a dust mite allergy, just as some people have allergies to certain foods, pollen or any other substance. New studies, however, have found that high levels of dust mite excretions may cause some people to have an allergic reaction that they would not have if levels were average.
According to research introduced by the National Institute of Environmental Health Sciences, anywhere from 18 percent to 30 percent of people in the United States suffer from a dust mite allergy, and approximately 50 percent of all U.S. homes have high enough dust mite allergen levels to induce a reaction in those who would normally not experience dust mite sensitivity.
A dust mite allergy is triggered when a person inhales dust or other airborne dust mite excretions. In some cases, external contact may also trigger certain allergy symptoms. Even though house dust has many components, studies have found that dust mite castings are the strongest.
Dust mite allergy has also been found to be more prevalent than originally thought. Up to 80 percent of asthma cases may be directly related to dust mite exposure. Eczema and hay fever may also primarily be caused by dust mites.
Dust Mite Allergy Symptoms
Symptoms of an allergic reaction to dust mites are caused by an individual’s immune system. When the immune system detects a potentially dangerous foreign object or substance in the body, it reacts to control or minimize the danger. People with a dust mite allergy have immune systems that are triggered by exposure to dust mite castings. The dust mite castings may be inhaled, or they may only come into contact with exposed skin.
When contact is made with the allergen, the immune system responds by creating antibodies. The antibodies, in doing their job, release histamines. Histamines are natural compounds that cause the body to react in ways that will protect it from diseases and infections. Unfortunately, protecting the body with histamines produces some side effects, and these side effects are the allergy symptoms.
Not everyone who is allergic to dust mites experiences the same symptoms, and symptoms may change from one reaction to the next in a single individual. Symptoms are often worse after spending time in rooms with poor ventilation, high temperature or high humidity.
Those who are allergic to dust mites may experience one or more of the following symptoms:
• Runny nose, nasal congestion, or sneezing
• Watery, red and/or itchy eyes
• Difficult breathing or wheezing
• Itching inside the mouth
• Pressure in the face
• Bags under the eyes
• Redness of the skin, rash, or eczema
When symptoms are present, they are rarely recognized as a dust mite allergy because these symptoms are common to many other ailments. A physician will be able to determine if the symptoms are caused by dust mites through blood and skin tests.
Dust Mite Allergy Treatments
The first step in treating a dust mite allergy is detecting where dust mites are located inside the home. Dust mites are usually detected by taking samples from several locations and then visually inspecting them under a microscope. Those areas testing positive for dust mites can then be treated through one or more means. Some of the most common and effective ways of treating dust mite allergies are as follows:
• Over-the-counter drugs – The symptoms of dust mite allergies can be controlled with over-the-counter antihistamines. These types of drugs reduce the histamine levels that are causing the symptoms. However, antihistamines can have other side effects, such as drowsiness.
• Mattress encasements – Mattress encasements are one of the most effective means of treating a dust mite allergy because some of the highest concentrations of dust mites are in mattresses. Mattress encasements create an impervious barrier around the entire mattress, so dust mites and their excrement are trapped inside, and no new ones can get inside. The dust mites already inside eventually die when their food supply and moisture run out.
• Hot water and steam – Washing clothes and bedding in very hot water for at least 10 minutes will kill any dust mites inhabiting the items. Steam-cleaning carpets, rugs and furniture will also kill dust mites. If hot water or steam cannot be used on certain items, they can be frozen for 48 hours as an alternative.
• Dust mite air purifiers – Air purifiers can help to remove dust from the air. When less dust is in the air, fewer allergens are inhaled. In addition, removing dust from the air also removes dead skin cells, depriving dust mites of their primary food source. Air purifiers with HEPA filters are recommended because they remove up to 99 percent of allergens from the air.
• Atmospheric controls – Dust mites thrive in temperatures higher than 70° F and relative humidity higher than 50 percent. Reducing temperature and humidity will create a less hospitable environment.
• Pesticides – No pesticides are currently labeled for the control of dust mites. However, two substances that are not considered pesticides are known to kill arachnids of all types: benzyl benzoate and tannic acid. Although studies show that the health risks of using either of these substances is low, it is still only recommended as a last resort.
Lyon, Willam F. Ohio State University Extension Fact Sheet. “House Dust Mites.” http://ohioline.osu.edu/hyg-fact/2000/2157.html
Mayo Clinic. “Dust mite allergy.” http://www.mayoclinic.com/health/dust-mites/DS00842
National Institute of Environmental Health Sciences. “Dust Mites.” http://www.niehs.nih.gov/health/topics/conditions/asthma/allergens/dustmites/
National Institutes of Health. “X-Plain Dust Mite Allergy Reference Summary.” http://www.nlm.nih.gov/medlineplus/tutorials/allergiestodustmites/id039204.pdf