Transcript Parasites

Objectives:
1. To learn the different stages, types
and classes of parasites
2. To learn the host(s) of each, their life
cycle, damage and symptoms
3. To learn control methods and
common chemicals used for
prevention
Parasites and Economics
• Parasites cause many economic
losses
• Slow animals growth, lower feed
conversion, decrease production and
may cause death
• Early treatments decrease economic
losses
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Terminology
1. parasite— organism living in or at the
expense of another living organism
2. host— animal which serves as residence for
parasite
3. larvae— first immature stage emerging from
the egg
4. pupae— stage following the larval stage
5. nymph— any immature stage of a parasite
(larvae or pupae)
6. adult— last stage, lay eggs and reproduce
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Types of Parasites
Four types of parasitic organisms:
1.
2.
3.
4.
Fungi
Protozoa
Helminths – worms
Arthropods – ticks and insects
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Classes of Parasites
1. External— live outside digestive,
circulatory, reproductive and internal
organs as adults
2. Internal— live within digestive,
circulatory, reproductive and internal
organs as adults
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Control Methods
Since there are only two classes,
there are only two ways to control
them:
1. Externally— includes spraying, dusting,
dipping, pour-ons, injections, sanitation and
pasture rotation
2. Internally— putting chemicals into the body
(worming)
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Worming Methods
1.
2.
3.
4.
5.
Water
Feed
Paste
Drenching with a drench gun
Tubing with plastic tube and drench
gun
6. Bolus using a plastic balling gun
7. Injection
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External Parasites: Ticks
• Two families of ticks are
Argasidae and Ixodidae
• Three most important ticks:
1. Lone Star Tick – three
host tick (argasidae)
2. Gulf Coast Tick – three
host tick (argasidae)
3. Spinose Ear Tick – one
host tick – (ixodidae)
• Host - all livestock
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External Parasites: Ticks
• Life Cycle
– adult lays eggs hatching in 10-21 days
– eggs hatch, find host, attach and feed
on blood
– stay attached until adult hood, then
detach and lay eggs
– life cycle ranges from a few days to
several months
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External Parasites: Ticks
• Damage
– anemia
– weight loss
– death
• Symptoms
– unthrifty
– rubbing on objects
– unnatural head and ear
carriage
• Control
– pasture rotation
– cold winters
– chemicals
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External Parasites: Lice
• Host – all species
Life Cycle
– adults lay and glue eggs
to hair follicles
– eggs hatch in 1-2 weeks
and become adults in 2-4
weeks
– live entire life on host,
feeding on skin and
blood
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External Parasites: Lice
• Damage
–
–
–
–
irritation, rubbing and scratching
anemia
unthrifty
weight loss
• Symptoms
– rough hair coat
– rubbing
– scratching
• Control
– chemical control with sprays,
dips, dust, pour-ons and
injections
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External Parasites: Mites
• Includes many species
causing skin problems
such as scabies, scabs,
mange or barn itch
• Host – all species
• Life Cycle
– adults lay eggs on skin of
animal
– eggs hatch in 4 days
– feed on skin and reach adult
stage in about 12 days
– spend entire life cycle on host
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External Parasites: Mites
• Damage
– hair falls out
– skin becomes rough and
crusty
• Symptoms
– spots of rough, crusty skin
with no hair
– scratching and itching
• Control
– chemicals are used
– some are serious and USDA
will quarantine animal
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External Parasites: Screwworm
• Larval stage is a flesh
eating worm
• Adult stage is a fly
• Unless controlled,
larval stage will kill
host
• Host – all species
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External Parasites: Screwworm
• Life Cycle
– adult fly lays eggs at sight of a wound
– eggs hatch in 12-24 hours into maggots
feeding on flesh
– complete growth in five to seven days
– drop to ground and then burrow into soil
– pupal stage lasts for a few weeks
– emerge as flies
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External Parasites: Screwworm
• Damage
– sores
– weight loss
– permanent injury and
death
• Symptoms
– unpleasant odor
– large wounds
– seepage of blood serum
from wound
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External Parasites: Screwworm
• Control
– chemical control
– contact Southwest Animal
Research Foundation
– eradication program in
progress
• sterile male flies are
produced and released
• female only mates once
and lays unfertilized eggs
• There have only been a
few cases in the past 1520 years
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External Parasites: Heel Fly or
Cattle Grub
• Host – cattle
• Life Cycle
– adult fly lays eggs on hair of rear legs (lower part)
each spring
– eggs hatch and larvae enter host’s body through hair
follicles
– larvae migrate from back legs, to stomach area, to
shoulder, to middle back (many larvae die along the
way)
– larvae become grubs and cut a breathing hole in skin
– at maturity, they “pop” out of hole and fall to the
ground, burrowing into soil
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– emerge as a flies with no mouth in 2 months
External Parasites: Heel Fly or
Cattle Grub
• Damage
– holes in hide
– cattle run from flies which causes injury and weight
loss
– damage to meat
• Symptoms
– bumps on back
– cattle running in spring for no apparent reason
– presence of flies
• Control
– systemic insecticide before larvae reach back
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External Parasites: Horn Fly
• Host – all species
• Life Cycle
– adults lay eggs in
manure or dead
decaying matter
– eggs hatch into larvae in
24 hours
– larvae mature into pupal
stage in 5-10 days
– flies emerge from pupae
in 3-7 days
– reach maturity in just a
few days
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External Parasites: Horn Fly
• Damage
– flies bite and suck blood
– animals become annoyed,
results in weight loss
– flies transmit diseases
• Symptoms
– flies can be seen
• Control
–
–
–
–
chemical
feed additives
ear tags
sanitation
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Internal Parasites: Stomach
Worm
•
•
Host – all animals
Life Cycle
–
–
–
adults live as blood
sucking parasite
attached to the
stomach wall
eggs pass out with
feces and hatch in 1520 days
larvae are eaten and
travel to the stomach
where they mature into
adults
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Internal Parasites: Stomach
Worm
• Damage
– holes in stomach lining
– poor digestion
• Symptoms
– anemia (paleness of gums
and whites of eyes)
– weight loss
– dull hair coat
– unthrifty
• Control
– sanitation
– pasture rotation
– chemical wormer
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Internal Parasites: Strongyles
• Effect mainly young
animals
• Animals build an
immunity as they grow
older
• Also called blood
worms
• Host – all species
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Internal Parasites: Strongyles
• Life Cycle
– adult lives as blood sucking
parasite in small intestine
– eggs are laid and pass out in
feces
– hatch into larvae in 5-20 days
– larvae are eaten and travel to
small intestine
– larvae burrow holes into arteries
and internal organs causing much
damage
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Internal Parasites: Strongyles
• Damage
– most detrimental
– reduced digestion
– blocking of arteries
− organ damage
− colic in horses
• Symptoms
–
–
–
–
anemia
weight loss
rough hair coats
scouring
• Control
– sanitation
– pasture rotation
– chemical wormer
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Internal Parasites: Ascarids
• Largest of the round worms
• Host – cattle, sheep, hogs, horses
• Life Cycle
– adults live in small intestine, lay eggs which pass out
with feces
– eggs are eaten, travel to small intestine, hatch into
larvae and burrow holes through the intestinal wall
– larvae migrate through liver, heart and into lungs
– host coughs up larvae and swallows, returning larvae
to small intestine to attach
– adults may grow 8-15” in length
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Internal Parasites: Ascarids
• Damage
– to lungs and liver,
causing disease and
anemia
• Symptoms
–
–
–
–
dull hair coat
colic
weight loss
unthrifty
• Control
– sanitation
– pasture rotation
– chemical wormers
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Internal Parasites: Lungworms
• Host – all species
• Life Cycle
– adults live in lungs and lay
eggs
– eggs are coughed up,
swallowed, hatch and pass
with feces
– larvae are eaten and
passed into small intestine
– larvae burrow holes through
intestinal wall and go to
lungs where they mature
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Internal Parasites: Lungworms
• Damage to lungs, trachea
and bronchial tubes
• Symptoms
– coughing and forceful
breathing
– fever, stops eating and
becomes gaunt
• Control
– sanitation
– pasture rotation
– chemical wormers
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Internal Parasites: Broad
Tapeworms
• Host
– all species are a major host
– mites are intermediate host
• Life Cycle
– adults live in small intestine
and feed on food, not host
– may grow to lengths of 10-12
feet
– segments containing eggs
break off and are passed with feces
– eggs are eaten by mites and develop until eaten by
a major host
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– eggs hatch in small intestine and mature
Internal Parasites: Broad
Tapeworm
• Damage
– no physical damage
– compete for food
• Symptoms
– weight loss
– diarrhea
– unthrifty
• Control
– chemical control
– must be edible to tapeworm
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Internal Parasites: Liver Flukes
• Host
– cattle, sheep, goats and humans
• Life Cycle
– adults live in bile ducts and begin egg production
approximately 3 months after entering host
– eggs pass out through feces and must land in
water to hatch
– larva must attach to a snail to complete life cycle
– larva then encyst on water plants eaten by
livestock
– young flukes pass to small intestine, where they
burrow holes throughout the abdominal cavity
and enter the liver to live on blood
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Internal Parasites: Liver Flukes
• Damage
– fibrosis of liver
– thickening of bile duct
• Symptoms
– anemia
– weight loss
– death
• Control
– pasture rotation
– no wet areas
– use water troughs and chemical
wormers
– snail population control
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Summary
Parasites can cause numerous health
problems for livestock and humans.
There are various chemical and natural
ways to prevent parasite infections.
Necessary precautions are imperative in
order to prevent infection.
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