www.pestmagazine.co.uk September & October 201430 pest
Dust in time!
Dust mites live in the fine layer of minutedust particles that continually settles onhousehold items. They are found almostworldwide but their numbers areconsiderably reduced at high altitudes andin dry climates.
The mites favour homes with high humiditylevels and constant warm temperatures and,under these conditions, mite populations canexplode, although there are some seasonalfluctuations.
The mites are known to concentrate in hightraffic areas in homes and on certainfurniture items, especially beds, upholsteredlounges, chairs and in carpetswith long fibres. They areattracted to these areas for foodand they feed on shed humanskin scales and secretions,house dust, fungal spores,pollen grains, plant fibres andinsect scales.
Dust mites dislike strong light and will takeharbourage in the seams, ledges, andframework of furniture when exposed. Dueto their light weight, dust mites can becomeairborne during activities such as bedmaking, and in this way can be distributedthroughout the room or house.
Adult mites are described as white to a lighttan in colour; they are difficult to see withthe naked eye, as they measure only 0.5mmin length, and the developmental stages aresmaller.
The body of the mite is oval shaped andcovered with fine striations.
Identification of dust mites isperformed with the use of light
microscopy and taxonomic keys, after acomplex process of separating the mitesfrom the dust substrate. Very fewlaboratories have the taxonomic skills toconfirm the identification of these mites.
There are five stages in the life cycle of adust mite; from the egg, the larvae stage,then two nymphal stages, and finally theadult.
The whole life cycle from egg to adult takesapproximately one month to complete.Mature female mites can lay from one totwo eggs per day. Adult mites can live up to
two months but this is dependent on thelevels of humidity and temperature oftheir surrounding environment.
House dust mites have beenknown to be associated withallergies since the 1960'sand have become a focusover recent years for theirinvolvement with respiratoryailments, particularly as atriggerfor asthma.
They do not bite, sting ortransmit diseases, but harbour strongallergens in their bodies as well as in theirsecretions, excreta and shed skins.
Constant contact with these allergens cantrigger respiratory and dermatologicalcomplaints, which may include allergicrhinitis, childhood eczema, various otherallergies, as well as asthma.
Patients with a suspected dust mite allergycan be tested for such an allergic responsevia skin prick tests in a specialist allergyclinic.
Identification is difficult
Dust mites and asthma
Dust mites are not an insect pest controllers often come into contact with.What brought them to our attention at was the all too often occasionswhen national newspapers discuss the perils of bed bugs and then promptlyinclude a photograph of a dust mite! So we thought the moment was rightto review this pest.
Pest
Dust mites are a cosmopolitan group of arthropods that refer to a number of species whichare normally found in the home. The most common species in both Australia and the UK is
from the family Pyroglyphidae. However, there are arange of other species that are loosely named 'dust mites', as well as a number of predatorymites that share the same dusty environment.
Dermatophagoides pteronyssinus
Our thanks go to StephenDoggett and Merilyn Gearyfrom the Department of MedicalEntomology at WestmeadHospital, NSW, Australia forthis informative article.
September & October 2014 www.pestmagazine.co.uk 31pest
It is estimated that around 70-80% ofpeople in warmer climates have an allergyto dust mites
Allergies from house dust mites can bemanaged by immunotherapy using miteextracts in conjunction with reducing themite population in the home of the patient.
It is virtually impossible to eliminate all dustmites from a household, but areas wheremites tend to congregate can be targeted:
Wall-to-wall carpet should be reducedand replaced, where possible, withsmooth, hard surfaces that are easy toclean;
Upholstered furniture should beavoided;
Mattresses and pillows should beencased in especially manufacturedencasements that aid in the exclusion ofmites;
Bedding and curtains should beselected on their ability to withstandfrequent laundering.
In addition:
Thorough vacuuming on a regular basisusing a cleaner with a high efficiency
particulate cleaner, including allmattresses, especially the seams andframework of the bed, will also help toreduce dust mite populations and abuild up of the allergens;
Steam cleaning can readily kill themites and therefore subsequently reducethe allergens;
A reduction in humidity levels byincreased ventilation throughout thehouse and the use of air conditioning,will assist in maintaining mites at alower level.
There are various products registered fordust mite control including permethrin andeucalyptus oil, which are largely aimed atthe DIY market.
However, these chemical methods will notprovide long-term benefits in reducing mitepopulations, nor will they decrease theallergens.
This means that proper housekeeping with ahigh degree of hygiene by the homeownershould be the main means of managingdust mites. As such, it is usually unnecessaryfor pest managers to be involved in dustmite control.
Managing allergies
Chemical means of control
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This article first appeared in , the leading independentAustralian magazine for pest professionals
Professional Pest Manager
www.ppmmagazine.com.au
This article details best practice for areduction in dust mite levels.However, a search of the CochraneCollaboration* concluded that therewas no evidence for any beneficialeffect of either non-chemical orchemical mite controls on asthmalevels.
In the paper by authors P C Gøtzscheand H K Johansen it states: “The housedust mite is the allergen to whichasthmatics are most frequently sensitive,and the acute effects of exposure onthe symptoms of asthma are wellestablished. The explanation that wefind most plausible for the lack of effectof the interventions is therefore that themethods we have reviewed do notadequately reduce mite antigen levelsas it seems inherently implausible tosuggest that complete removal of amajor provoking agent would beineffective. It is important to remember,however, that mite-sensitive asthmaticpatients are usually sensitive to otherallergens, so that successful eliminationof only one allergen may have limitedbenefit, whatever its success.”
It’s a complex issue.
* The Cochrane Collaboration is aninternational, independent, not-for-profitorganisation, funded by a variety of sourcesincluding governments, universities, hospitaltrusts, charities and personal donations.Cochrane's vision is that making decisionsin healthcare should be informed by high-quality, timely research evidence.
Bad newsfor asthmasufferers
A quick internet search revealed a variety of DIY potions claimingto rid the user of dust mites. Unhelpfully, the active ingredients ofmost were not detailed.
One site, Hygiene Supplies Directhas a variety of products listed
including Protector P Dust Mite spray which claims to 'Get Rid OfDust Mites! Government Tested. Guaranteed To Work!'
At the time of going to press, it goes on to say 'The choice ofprofessionals is now available to the general public. Kills dustmites – Fast! Protection lasts for up to 3 Months!' Really?Unsurprisingly, no references to substantiate the claims are given.
The a.i. is 0.2% permethrin and the product is sold bymanufacturer Agropharm. Their own website does not make quitesuch wild claims.
Other products available for dust mite control include ultrasonicdust mite repellers and the familiar range of pillow and mattressencasements.
Are these products and the information provided really helpful?No wonder the great British public gets confused by such claimsand most likely distressed when they find their purchase makeslittle headway in solving the problem. None of this does anyfavours for the image of pest control professionals.
