Dust-Mite Allergies


These little bugs are so small that between 100 and 500 individual mites live in a single gram of dust. Despite their size, dust mites cause some big problems. Or more specifically, their feces do.

Related to spiders and ticks, dust mites live in fabrics like bedding and carpeting that collect dust. While we used to believe that people were allergic to dust, researchers now know it's not the dust itself, but the mites that live in it that cause the problem. Dust mite droppings (feces) contain a protein that is an allergy trigger for the majority of allergic individuals. And these mites live everywhere dust accumulates, particularly in bedding, upholstered furniture, carpeting and stuffed animals. They grow best where it's warm and humid. About the only places they don't flourish are where it's very dry or the altitude is more than 3,000 feet above sea level. Mites live on a diet of skin scales naturally shed by humans, and each mite produces between 10 and 20 waste pellets each day. Each egg-laying female can increase the population by 25 to 30 mites every three weeks.

These mites are no danger to nonallergic people because they don't bite humans or spread disease. But their numbers have increased dramatically in the past 20 to 30 years, especially during winter months, as more focus has been spent on building energy-conserving homes in which ventilation is limited and temperatures tend to be warmer. Here's how to take the might out of dust mites:

Wage battle in the bedroom

In most homes, the highest concentration of dust mites is in the bedroom, where they love to get cozy in mattresses, pillows and carpeting. The bedroomalso happens to be a place that you spend a lot of your time. When you lay down to sleep, you bring your nose within inches of some of the most popular gathering places for mites. Dust mite proteins are reasonably heavy particles, so they only stay airborne for a short while after you stir them up. If you shift your position on your mattress, a large quantity of these proteins can drift into the air just above your mattress surface, which is the air you breathe during the night. Making adjustments to reduce exposure to mites in your bedroom and especially your bed can be your most powerful way to fight dust mite allergy.

• Wash all bedding — including mattress pads, comforters and blankets — in hot water every seven to 10 days.

• Consider covering mattresses, box springs, and pillows in allergen-proof encasements, so the mites and their debris can't pass through. These mattress and pillow covers are made with tightly woven material. They have been found to reduce dust mite allergen in the air, but a measurable improvement in asthma symptom severity has not been seen in several studies that have attempted to show such a benefit. However, many experts still believe that these covers may be worth their modest cost.

• Keep a bedspread on your bed all day to collect dust, but carefully remove it from your bedroom (without shaking it) before you go to sleep.

• Avoid feather or down pillows. Instead, use polyester fiber-fill such as Hollofil or Dacron. Dust mites like synthetic pillows as much as feathers or foam, but synthetic pillow can be washed. No matter what you use, all pillows should be encased in allergen-proof covers.

• Don't use fuzzy blankets unless they can be regularly washed. They tend to collect more dust than blankets with a thin weave. Other dust collectors include stuffed animals, wall-to-wall carpeting, rugs that are not easily washable, and bed canopies. These items should be removed from the bedroom or avoided altogether.

Dry up

Mites like it warm and moist, so dehumidifying your home can help. Air conditioning helps reduce humidity, but you may also want to invest in a dehumidifier, especially if you live in a southern climate. Dust mites do best when the relative humidity is above 55 percent, and grow poorly when it's below 45 percent. When indoor temperatures are close to 80° F, humidity should be lowered below 40 percent. Meanwhile, clean your air-conditioning filters every month.

Wooden it be nice

Big, overstuffed furniture provides the perfect comfort zone for dust and mites. So if you're shopping for new furnishings, choose sleeker, pared-down wooden products with less stuffing. Whenever possible, replace wall-to-wall carpeting with wood or sheet-goods flooring and with area rugs that can be laundered easily. Of course, you'll need to use dust-removing polishes on wood furniture and floors.

The only good mite is a dead mite

Poisoning of dust mites with benzyl benzoate (Acarosan) dry foam carpet and furniture cleaners once every six months may help if you do not remove rugs.

Think twice before filtering them out

Installing air cleaners and air filters to remove dust is a costly solution that may not be worth the investment. Air cleaners are available as attachments to your heating system or as portable units that can be moved from room to room. The most effective ones have high-energy, particle-arresting (HEPA) filters capable of trapping very small particles. Others use electrical charges, static electricity or ionizers to trap particles. None work well enough to substitute for other steps you can take to cut down on indoor allergens. Air cleaners that generate ozone gas have no effect on allergens in the air and may worsen allergy symptoms because the ozone they emit can irritate the respiratory system.

Avoid panic with tannic

No one is able to completely eliminate mites from a home. If you want to do everything you can to prevent dust mite allergy, it may help if you repeatedly treat places where dust mites gather with a substance (tannic acid) that chemically changes the protein that is the source of dust mite allergy so it can no longer act as an allergy trigger. Try treating carpets and furniture with a spray containing tannic acid.

This treatment may not help control dust mite allergy, probably because it is difficult to use it frequently enough to provide a noticeable benefit. Tannic acid must be regularly reapplied because it does not kill mites, and mites will quickly produce new feces pellets.

Last updated January 12, 2012

Parents can HALVE their baby's risk of asthma if they avoid exposing them to house dust, nuts, eggs and dairy products

• Findings contradict the 'hygiene hypothesis' that exposure to allergens and germs boosts immunity

• 11% of children protected from allergens such as nuts and dairy products developed asthma

• Compared to 27% of those exposed to the allergens

Protecting babies from highly allergenic foods and dust mitesin their first year of life can prevent the development of asthma during childhood, a new study has discovered.

Researchers found that a child's risk of developing the condition is reduced by more than half if their contact with common triggers of allergy

The new research contradicts the so called ‘hygiene hypothesis’ – the theory that being exposed to allergens at a young age reduces a child’s risk of developing asthma and allergies.

Professor HasanArshad, a consultant in allergy at Southampton General Hospital, conducted the 23-year study.

Protecting babies from highly allergenic foods and dust mites can actually prevent the development of asthma during childhood

He said: ‘Although genetic links are arguably the most significant risk factor for asthma in children, environmental factors are the other critical component.

‘Although this was a small study, we have found that the risk of developing asthma at some point during childhood is reduced by more than 50 per cent if we introduce control of a child's environment.’

Researchers assessed 120 patients with a family history of allergies.

The children were recruited at birth 23 years ago to find out whether or not breastfeeding mothers who avoided dairy products, eggs, soya, fish and nuts, while also using vinyl mattress covers and pesticides to kill dust mites, had a lower risk of seeing their children develop asthma.

They performed follow-up tests when the children were two, three, four, eight and 18 and found that while only 11 per cent of those in the prevention group had developed asthma by age 18, more than a quarter of those who were naturally exposed to substances linked to allergic reactions had the condition.

Mr Arshad said: ‘By introducing a combined dietary and environmental avoidance strategy during the first year of life, we believe the onset of asthma can be prevented in the early years and throughout childhood up to the age of 18.

The new research contradicts the so called 'hygiene hypothesis'

‘Our finding of a significant reduction in asthma using the dual intervention of dust mite avoidance and diet modification is unique in terms of the comprehensive nature of the regime, the length of follow-up and the size of the effect observed.’

The research, published in the journal Thorax, and funded by the National Institute for Health Research (NIHR), is the first study to show a persistent and significant reduction in asthma throughout childhood.

Mr Arshad, who is also chair of allergy and immunology at the University of Southampton, and is based at the NIHR Southampton Respiratory Biomedical Research Unit, said there was now an urgent need to replicate the findings in a large multi-centre study.

Asthma is an increasingly widespread problem in the UK with one in 11 children currently receiving treatment for the condition.

A recent study by the Harvard Medical School revealed contradictory information to that found by the researchers at Southampton General Hospital – it showed that dirt and germs can protect against disease - and that our indoor-based, ultra-clean lifestyles are bad for our health.

It supported the idea that without exposure to dirt and germs early in life, the immune system does not learn how to control its reaction to everyday invaders such as dust and pollen.

This can lead to it miss-firing later in life, leading to allergies and other illnesses.

The evidence came from researchers who studied germ-free mice, bred in a bubble, kept in sterile cages and fed sterile food.

The lungs and bowels of the germ-free mice contained extra-large numbers of a type of immune cell blamed for asthma and bowel problems.

And when the germ-free mice developed asthma or bowel condition colitis, it was much more severe than usual, the journal Science reported.

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25 April 2013


Can my vacuum help me fight mattress allergens?

Can your vacuum reduce your allergy symptoms by removing dust mites -- like the the one shown here -- from your mattress?

50 million Americans suffer from allergies? More than half of all Americans have an allergic response to at least one substance, and more than half of American homes have six (or more) common, detectable allergens [source: American Academy of Allergy Asthma & Immunology]. Along with animal dander, dust, mildew and mold spores, dust mites are one of the most common triggers of indoor allergies and asthma. Indoor allergies are usually caused by small particles that we inhale, and because dust mites are microscopic, you'll find them even in the cleanest of homes. They like to eat the dead skin cells that flake off of us as we go about our day -- we shed about 0.05 ounce (1.5 grams) of skin every day, which will feed about one million hungry dust mites [source:Asthma and Allergy Foundation of America].

So where does this huge mite population live? They live, eat, breed and die in our sofas, chairs, carpeting, curtains, bedding and mattresses. Mites have a short life span, and in just 3 weeks, a new generation of dust mites will inhabit all your stuff.

Unlike bedbugs, dust mites don't bite -- it's the protein in their waste products (decaying dust mites as well as dust mite fecal matter) that can trigger an allergic response in an estimated 18 to 30 percent of Americans [source: Johannes]. While keeping them at bay may seem impossible, there are ways to minimize your exposure.

Let's look at the bedroom, since it's where we spend most of our time. If you sleep eight hours each night, that's about 3,000 hours a year in bed. Keeping your mattress free from dust mites is key to waking up feeling refreshed rather than sneezy and tired. Encasing your mattress and pillows in allergen-proof covers, and washing and drying all bedding on your appliances' hottest settings -- the water needs to be at least 130 degrees F to kill dust mites -- every week is one of the best ways to reduce allergens in your bed.

Vacuuming your mattress, however, may not do as much to relieve a dust mite problem as you may hope. As it turns out, mites are hearty -- not only can they survive a trip through the wash if the water isn't hot enough, they can also survive your attempts at vacuuming them up. As many as 95 percent of dust mites continue to lead their lives after you've tried to vacuum them from your mattress [source: Asthma and Allergy Foundation of America]. How can this be? Because they don't live on the surface; rather, they live deep within the stuffing of the mattress.

While vacuuming your mattress isn't very effective in reducing mattress allergens, people who suffer from allergies should try using HEPA (high-efficiency particulate) filters when vacuuming carpets, curtains and other items that are mite-friendly but not stuffed.