Transcript Ectoparasites - Kristin Singer

Ectoparasites
The Arthropods
Phylum
Arthropoda
Class
Insecta
Class
Arachnida
Class
Pentastomida
Class insecta
Class
Insecta
Order
Diptera
(flies)
Order
Phthiraptera
(lice)
Order
Siphonaptera
(fleas)
Class
Arachnida

Ticks and mites are small arachnids
in the Order Acarina. Many are
parasitic on animals and humans, &
vary greatly between families.
Class Pentastomida (“tongue
worms”)

Very unusual insects, may be related
to sarcoptiform mites or to annelids
(earthworms).
Parasite Species Agent Disease
Parasite
Species
Mosquitoes Horse
Agent
Virus
Virus
Culicoides
Mites
Flies
Virus
Cestode
Nematode
Virus
Disease
WNV
WEE; EEE;
VEE
EIA
Tapeworms
Summer
sores
(habronema)
EIA
Bot fly

Female bot flies lay
from 150 to 1,000
yellowish eggs. The
eggs are firmly glued to
the hairs of the
forelegs, belly, flanks,
shoulders and other
parts of the body of the
horse. While the fly's
egg laying does not
cause the horse pain,
the horse often is
bothered by presence of
the fly.
Bee-like adult
Bot flies
• Does not bite; may bother
• Eggs on legs
• Licked by horse
• 4 weeks in oral mucosa
• Overwinter in stomach
• Ulcers
• Control:
– External: insecticide on
legs
– Internal: broad spectrum
anthelmintics
Horse and deer flies
• Large
• Multiple species
• Females only bite
• Generally: larvae in water or
damp locations
• Strong flyers
• Daytime feeders
• Painful bites
– Horse flies: anti-coagulant
– Secondary infections
– Transmission of disease:
• EIA
• Anaplasmosis
• Larvae – not possible
• Adults – fly repellants
Stable flies
• Both males and females
• Around premises
• Strong flyers
• Painful bites
• Soggy hay/manure hay
• Transmit
– EIA
– Habronema
• Identify and control
breeding site(s)
• Insect repellants
Summer sores (habronemiasis)
• Caused by the larva of
nematode species;
Habronema muscae
Habronema majus
• Stomach-dwelling
• Indirect life cycle
• Fly-transmitted
• Seasonal
• Hypersensitivity component
• “Aberrant parasitism” when
larvae deposited in wounds
• Esp. eyes, conjunctiva, male
genitalia, distal limbs
• Prevent - ivermectin
Culicoide Hypersensitivity
( Queensland itch, Sweet itch, Summer
itch)
Culicoides hypersensitivity
•
•
•
•
•
“Sweet itch”
Individual horses
Acute hypersensitivity
Spring-summer
Regresses in fallwinter
• Tail, rump, back,
withers
No-See-Ums
• Culicoides & sandflies
• Need aquatic habitats
• Allergic reactions in
horses
• Also:
– BTV bluetongue virus
– EHD epizootic hemorrhagic disease
– EIA
Mosquitoes
• Wet sites
• Only females feed
• Still water
• 6 – 7 days to complete life
cycle
• Day or night feeders
• Variable year to year,
depending on moisture
• Many species
• Diseases:
– WEE
– EEE
– WNV
– VEE
Mosquito control
• Control large wet breeding sites
– Pest control districts
• Keep water containers to
minimum:
– Empty troughs every ~3 days
• Bacillus thuringensis (BT) dunks
• Screen water containers
• Stable horses dawn and dusk
• Insect zappers relatively
ineffective
• Topic sprays for horses
Topical anti-mosquito products
• Pyrethrins - chrysanthemum extract
– Effective; short duration
• Pyrethroids - synthetic
– Low toxicity; longer-lasting than pyrethrins.
– Permethrin and cypermethrin
• Plant extracts
– Citronella, eucalyptus, pennyroyal, cedar, geraniol etc.
• DEET (N,N-Diethyl-meta-toluamide, is the most
common active ingredient in insect repellents)
– Now EPA approved for horses
– Licensed veterinarians.
– Repellent only - not insecticidal
Blowflies and
fleshflies
• 60 species
• Cadavers and wounds
• Eggs in moist wool,
open wounds or break
in the skin
• Rare in cattle or horses.
• Painful – can be fatal
• Prevent by proper
insecticide treatments.
• Treat with insecticide
applications
Screwworm
• New World species
• Infects live warm blooded
species
• Infects people
• Open wounds and healthy tissue
• Eradicated in US
• Esp. newborns
• High mortality when untreated
• Latin America
• Controlled by sterile male
release
• Reportable to USDA
• Periodic incursions to USA
Horn flies
• Blood suckers
• Eggs in fresh manure (<10 min)
• Consume 10μl blood daily
– 3000/cow=30 ml/day
• Rapid life cycle (10 days)
• Strong flyers
• Live on cattle
• Nuisance:
– Cattle
– Horses
• Insecticidal ear tags
– On host a lot
• Dragging pastures to break up
feces
Acute hypersensitivity reactions in
horse
Acute hypersensitivity reactions
in horse
Lice • Sucking – blood
• Biting – surface debris
• Location specific
• Whole life on host
• Winter
• Attack all ages esp.
• Head, neck, shoulders,
and rump
• Irritate skin
• Control in fall
• Pour-on formulations –
treat twice 3 weeks apart
*Zoonotic
Mange mites
• Now uncommon
• Burrow in skin
• Dermatitis and
hypersensitivity
reactions
• Transmission by:
– Direct contact
– Fomites
• Ivermectin
• Decontaminate stables
and grooming equipment
Demodectic Mites



The demodectic or follicular
mite is a microscopic
(0.23mm), cigar shaped
worm-like mite that lives
within the skin.
All stages of the life cycle are
often found within the hair
follicle and sebaceous
glands.
The mite causes nodular
lesions in the skin usually
around the neck and
shoulders.
Chigger Mites

Chigger mites
(redbugs) make up a
large group of
species which
occasionally cause
problems for both
horses and man.
They cause intense
itching and reddish
welts on the skin.
Mite Control
Mange control requires isolation of
infested animals and thorough wetting of
the whole animal with timed applications
of approved pesticides.
 Chiggers can be controlled by application
of detergent wash containing one of the
insecticides registered for other mites.
Area control is not feasible.

Ticks
• Multiple species
• Seasonal activity varies:
winter vs. summer
• Some have multiple hosts,
depending on stage
• Dermatitis
• Transmission:
– Anaplasmosis
– Tularemia
– Tick paralysis
– Babesiosis (horses)
• Topical/systemic acaricides
Spinose ear ticks feeding
External parasites horses
Agent(s) Impact Disease Control Comment
Stable fly
Habronema ++ “Summer
sores”
Anthelmitic Summer
Biting midges
Culicoides
++ “Sweet itch” Stabling
Steroids
Summer
Flies
(stable, house,
horse, deer)
+ Annoyance
Wounds
Repellents Summer
Stable fly
Major insecticide classes
Class Example Notes
Botanicals Pyrethrin family Ear tags
Pyrethroid family Safe
Organophosphates Tiguvon® (fenthion) Sprays
Carbamates Ear tags
Oral (some)
Toxic!
Formamides Amitraz Lice/ticks
Fatal to horses
DDT derivatives Methoxychlor Horses
Dust
Sprays
Keys To Pesticide Safety

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
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
Before using any pesticide, stop and read the
precautions.
Read the label on each pesticide container
before each use. heed all warnings and
precautions.
Store all pesticides in their original containers
away from food or feed.
Keep pesticides out of the reach of children, pets
and livestock.
Apply pesticides only as directed.
Dispose of empty containers promptly and safely
References

http://edis.ifas.ufl.edu/IG139