prevent disease, disability and premature death mite biology & control female scabies mite
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Prevent Disease, Disability and Premature Death
Mite Biology & Control
Female Scabies Mite
Prevent Disease, Disability and Premature Death
Relate the biology of mites to appropriate control measures.
Objectiveهدف
Prevent Disease, Disability and Premature Death
Overview مرور
Characteristics and Habits
Life Cycle
Medical Importance
Control Measures
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Mites
Not all mites are of medical importance. We will be concentrating on the following:
Scabies
Chiggers
Dust Mites
Rat Mites
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Mites
Other mites of some Importance
Forage Mites
Straw Itch Mites
Poultry Mites
Follicle Mites
Cable Mites
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Biology
Mites are arachnids closely related to ticks
Life cycle : egg, larva, nymph and adults
Nymphal stage s; protonymph, deutonymph and tritonymph (not present in all mites)
Considerably smaller than ticks
Three body segments
Mouthparts consist of fewer segments
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Biology
Have varied appearances and food sources
free-living predators
external parasites (most)
internal parasites (very few)
plant feeders
stored-products pests
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Medical Importance
Affect the health of man in three ways
By causing dermatitis e.g. scabies and chiggers
As vectors of diseases i.e. scrub typhus and Rickettsial pox
By causing allergic reactions in man e.g house dust mite
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Sarcoptes scabiei
variety hominis causes scabies in humans
variety suis causes swine mange
variety equi causes horse mange
Sarcoptic Itch Mites
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Sarcoptes scabiei
Gravid females form burrows in the skin where they lay eggs
Larvae burrow out to the skin surface
they mature and mating occurs here
Eggs and debris are left within burrows
Scabies (Seven-year Itch)
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Scabies
Transmitted through intimate contact
Immunity appears to develop over time
Outbreaks occur sporadically
Initial effects usually not noticed for first month
Scratching leads to complications
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Chiggers
A.k.a. called Red Bugs
Numerous species called chiggers in genus Trombicula
Larval mites wait on grass blades for a host to pass by
Only larvae feed on man
Nymphs and adults
are predators
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Behavior
They don’t burrow into the skin
Mouthparts are inserted into a pore or hair follicle
Inject digestive fluid into cell, then feed on ruptured cell contents
Mite feeds and then leaves host
Welt and itching occur after mite is gone
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Behavior
Once on the host the mite crawls around looking for a suitable feeding site
They love elastic
socks
briefs
bras
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Chiggers
Bites commonly cause
itching in about 3 to 6 hours after feeding
dermatitis develops in about 10 to 16 hours
secondary infections can occur if bite wounds are scratched
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Scrub Typhus
Transmitted from Leptotromidium mites infected with Rickettsia tsutsugamushi
Found in South East Asia
Mites and disease are associated with
“fringe habits” transition line between wooded and maintained
“mite islands” patches of vegetation harboring large numbers of mites
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Dust Mites
Dermatophagoides pteronyssinus
Tiny mites that feed on shed human skin
They DO NOT bite!
People suffer from allergic reactions to:
excreta
cast skins
secretions
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Dust Mites
Higher humidity levels are more conducive to mite survival
Mite populations are
present year round
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Rat Mites
Blood feeding mites associated with rodents; several species are involved
They occasionally inflict painful bites
Can also transmit rickettsial pox (Liponyssoides spp. ) and possibly endemic typhus
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Rat Mites
Most commonly found in buildings infested with rodents
Eliminate the rodents and the mites will not be a problem after about two weeks
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Tropical Rat Mite
Vector of Epidemic Hemorragic FeverDisease is probably viralRodent population forms reservoirCases documented in Korea
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Forage Mites
Several species are involved
Normally infest grains, flour and cheese
Food handlers are occasionally attacked
AKA
Grocer’s Itch (Glycyphagus domesticus)
Copra Itch (Tyrophagus castellanii)
Vanillisme (Acarus siro)
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Forage Mites
Allergic responses also can occur
Intestinal disturbances due to consumption of infested food can also be a problem
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Straw Itch Mites
Pyemotes tritici
A predator in agriculture crops
Bean, pea & boll weevils, grain moths
Workers come into contact with the mites while handling straw and other commodities
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Poultry Mites
Blood feeding mites of chickens and other birds; several species are involved (Dermanyssus gallinae, Ornithonyssus sylviarum)
Occasionally feed on people; AKA poultryman’s itch
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Poultry Mites
Commonly associated with:
English sparrows
starlings
pigeons
Look for bird nests close to buildings
chimney
windows
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Follicle Mites
Demodex folliculorum
Most humans are infested
Occur in hair follicles around the eyes and nose
Cause no discomfort to the host
Similar mites cause demodectic mange in dogs
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Cable Mites
Cause static to occur in TV broadcasts
Infest coaxial cable resulting in a degradation of the cable line
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Cable Mites(the real story)
Not an actual species
Some people think they are infested with mites or other insects
Can be static electricity
Allergic responses to chemicals or medication
Delusory parasitosis
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Surveillance for Mites
Very difficult to do
Doctors can do skin scrapings from patients
Black plate method
Look for hosts (rats and birds)
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Control
Personal hygiene
Chemical (permethrin, lindane, crotamiton, gamma-BHC)
Chemical control presents problems due to dosage restrictions and development of resistance
Personal protection (deet, permethrin)
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Summary
Characteristics and Habits
Life Cycle
Medical Importance
Control Measures
Prevent Disease, Disability and Premature Death
Questions?
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