1 Issue No. 30 Apr 2013

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Issue No.30  Apr 2013




Morgellons Disease


Published by the

Pest Control Advisory Section

TSE Pan,  Assistant Pest Control Officer

More information on pest prevention and control can be obtained from other pages of our website. 

Morgellons Disease


Morgellons disease (MD), emerging in recent years, 

is a controversial dermatological disorder in which 

patients frequently claim that small insects are biting 

or living under their skin.  Although most of the MD 

cases were reported in the United States of America, 

an increasing number of similar cases has been 

recognized worldwide. 


Despite the lack of generally accepted MD symptoms 

by the medical community, patients always complain 

of stinging, burning, biting sensations and formation 

of unusual fibers found both subcutaneously and 

emerging from spontaneously appearing skin lesions.

Delusional parasitosis

Many medical practitioners regard MD as a form of 

“delusional parasitosis”.  In delusional parasitosis, 

patients hold a delusional belief that they are 

infested by parasites and experience a sensation 

similar to insects crawling on or under the skin.  

Centers for Disease Control and Prevention (CDC) 

of U.S.A. started a MD research in 2006 and found 

no infectious or environmental links to the disease.  

CDC suggested that the disease could be a form of 

delusional parasitosis.  

Possible infectious agent(s)

In contrast, latest studies demonstrated that MD 

patient’ skin lesions with unusual fibers are not self-

inflicted or psychogenic.  The fibers were proved to 

be originating from human epithelial cells.  Studies 

discovered that MD patients are predominantly 

infected with Borrelia burgdorferi, the spirochetal 

agent of Lyme disease (a tick-borne disease).  MD 

patients also demonstrated a higher than expected 

percentage of positive laboratory findings for 

other tick-borne diseases, suggesting the possible 

involvement of tick-borne co-infecting pathogens.


Presently, there is no definitive understanding of 

how MD is caused or transmitted.  There is also no 

conclusive evidence showing that MD is a vector-

borne disease.  Patients who suspect suffering from 

MD or with similar symptoms should seek advice and 

treatment from medical professionals instead of pest 

control professionals.  Moreover, keeping the living 

environment in good hygienic condition is essential 

in the prevention of pest infestation in premises. 


Pest Control Newsletter 

Issue No.30  Apr 2013

T. W. LEUNG,  Pest Control Officer


Mites are placed in the class Arachnida and are related 

to ticks, spiders and scorpions.  Most of them are very 

small and some are barely visible to the naked eye. 

Mites are not insects.  They lack wings and antennae.  

They differ from other arachnids by the total loss of 

body segmentation, resulting in the complete fusion of 

their bodies.  Their mouthparts are grouped together 

at the front of the body in a sort of a false head known 

as the capitulum.

Mites form the most diverse group of all the Arachnida 

and are found throughout the world in decomposing 

organic matter and soil, on plants, in fresh water, in 

deep marine habitats, on and in animals.  Mites have 

a large range of feeding habits, including internal and 

external parasites of vertebrates, invertebrates and 

plants, omnivores, fungivores, and detritivores.  

Although mites do not produce venom like spiders 

and scorpions, some species of them are still of great 

medical and veterinary significance.  This is because 

they can be important vectors of disease, and they 

themselves can cause allergic reactions.  Mites can 

cause conditions such as scrub typhus, dermatitis, 

asthma and scabies in humans, as well as mange and 

respiratory problems in some animals. They are also of 

commercial and agricultural importance because they 

are parasites of crop and ornamental plants, parasites 

of honey bees, and infesters of foodstuffs.  However, 

mites are extremely useful as bio-control agents, 

especially on other mites that are plant parasites.

Mites which we may encounter in our 

daily lives and have medical importance

Trombiculid mites 

Some members in the genus Leptotrombidium

including Leptotrombidium akamushi and L. deliense

are the principle vectors of the scrub typhus disease.  

They mainly live on vertebrates including rodents and 

insectivores at its larval stage as ectoparasites.  The 

adult and nymphal stages are free living and feeding 

on soil arthropods.  The larvae of mites, about 0.2 

mm long, crawl on the surface of soil or ground 

vegetation until they find a suitable host.  The larvae 

attach to mammals (humans are accidental hosts) 

before developing into adults.  In addition, the larvae 

attach firmly to the surface of the host's body with the 

mouth parts and suck up liquefied tissue.  The biting 

behaviour of mites is conducive to disease transmission.  

Prevention of Scrub Typhus

•  Avoid sitting or lying in scrubby areas;

•  Avoid hanging clothes on scrub or trees;

•  Disinfest  your  pets  regularly  which  have  visited

scrubby areas;

•  Apply insect repellent on clothes and the exposed

parts of the body before entering a scrubby area;


•  Wear light-colored long-sleeved clothes and long

trousers for going into a scrubby area to enable easy 

detection of mites attached to the clothes, if any.

Dust Mites

As the name suggests, dust mites are usually found 

in dust.  They present in large numbers in house dust 

under humid conditions.  They are found in almost 

every home, where they live in dust which accumulates 

in carpets, bedding fabrics and furniture.  As well 

as providing a habitat for the mites, house dust also 

contains their food source such as shed human skin 

scales.  The feces of these small creatures contain 

a particular protein, which is the principal cause of 

allergic reactions in some people when inhaled into 

the lungs.  The fecal pellets may also aggravate asthma 


Prevention of house dust mites

•  Frequent vacuums the premises preferably with a

water filter or High Efficiency Particulate Air filter 


•  Wash bedding, pillows and duvets in hot water at

55-60ºC regularly and preferably encase pillows and 

mattresses with allergen-impermeable covers; and

•  Remove,  reduce  or  modify  surfaces  that  provide

favourable microhabitats with regard to food 

buildup and relative humidity (e.g. eliminate 

soft toys, loose- and long-piled carpeting and 

dense upholstery with many folds and tucks) for 

elimination of favourable breeding grounds for 


Leptotrombidium deliense is 

a rodent-borne disease vector 

for the transmission of scrub 


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