Transcript Goat Parasites

GOAT PARASITES
Survey of endoparasites in goats in Ireland
DR THEO DE WAAL
SCHOOL OF VETERINARY MEDICINE
INTRODUCTION
• Parasites affecting goats
– Protozoa
– Arthropods
– Helminths
• Helminth parasite control
• Survey of goat parasite Ireland
• Anthelmintic resistance
PROTOZOA
• Cryptosporidium spp
– Intestinal epithelium
– Intermittent diarrhoea, long duration
– Important zoonosis
• Coccidiosis (Eimeria spp)
– Intestinal epithelium
Cryptosporidiosis - dirty hind end and pot
belly
– Several species, some more pathogenic than
others
– Host-specific
•
coccidia from sheep will not infect goat
– Profuse diarrhoea (with blood)
• Hygiene – clean water/feed & management
– isolation of sick animals
– avoid overcrowding
– don’t mix different age groups
Coccidiosis - dirty hind end and pot belly
PROTOZOA
• Toxoplasma gondii
– Complex life cycle
• Cat  mammals & birds
– Important cause of abortion in goats
– Important zoonosis
Abortion
Lesions on cotyledons of a placenta
Cats contaminate environment
ARTHROPODA
•
•
•
Mites
–
Burrowing (Sarcoptes scabiei) & Non-burrowing (Chorioptes & Psoroptes spp)
–
Feed on lymph and skin debris
Lice
–
Biting & sucking lice
–
Feed on dermal scales or blood
Ticks
–
•
Blood feeding
Skin irritation, itching & restlessness
–
Ticks also vectors of pathogens such as Anaplasma, Louping ill and tick
pyaemia
•
Sub-clinical – production losses
•
Spread by direct animal-to-animal contact
•
Treatment
–
Synthetic pyrethroids, Macrocyclic Lactone
–
Repeat after 2 weeks
Sarcoptic mange: A goat with generalized
lesions
(Wrinkled skin and loss of hair)
HELMINTHS
• Large, multicellular organisms
• Roundworms (nematodes)
• Flatworms (flukes and tapeworms)
Liver fluke
Tapeworms
Roundworms
FLATWORMS
• Fasciola hepatica – liver fluke
– Complex life cycle involving mammals (adult flukes),
snails as well as free living stages (metacercariae)
– Leaf like parasite affecting liver of many animals
– Seasonal disease: acute  chronic
– Anemia, bottle jaw
Liver fluke
• Rumen fluke
– Similar life cycle as liver fluke
– Immature parasite in small intestine
• Can cause diarrhoea
– Adult parasite in rumen
• Usually non-pathogenic
Rumen fluke
TAPEWORMS
• Adult tapeworms in small intestine
• Moniezia spp
Moniezia spp
– Complex life cycle: ruminants & free living mites
– Little pathogenic significance
• Larval stages in muscle of intermediate (goats &
sheep) host
• Taenia hydatigena
– Life cycle: dogs & wild canids (adult), ruminants (larval
stages) in abdominal cavity
– Usually asymptomatic, but heavy infection can lead to
liver lesions
Taenia hydatigena
• Taenia multiceps – “gid”
– Life cycle: dogs & fox (adult), ruminants (larval stages) in
brain
– Nervous symptoms – circling, stumbling, visual defects
• Control – dogs no access to carcasses; treatment
Taenia multiceps
ROUNDWORMS
• Large and diverse group
• Parasitic gastroenteritis (PGE)
– Abomasum, small intestine, large intestine
• Lungworms
Teladorsagia circumcincta lesions in abomasum
Muellerius capillaris nodules in lungs
NEMATODE LIFE CYCLE
L4, adult
• Short, direct life cycles
– 3-4 weeks
– weather-dependent
• Can overwinter on pasture.
• Ability to go into hypobiotic
(arrested) state (in host) when
environmental conditions are not
conducive to their development
(hot, dry or cold, dry).
L3
• Vary in their egg laying ability.
• Eggs look same under microscope.
L2
L1
THE EPIDEMIOLOGY OF
NEMATODE PARASITISM IN
GOATS AT PASTURE
11
TYPICAL SIGNS OF
PARASITISM
GI NEMATODES
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•
•
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Weight-loss
Diarrhoea
Rough hair coat
Weakness
(anaemia)
Bootle jaw
Decreased milk production
Death
LONG WORMS
• Generally mild
• Coughing
• Fast breathing
• Decreased milk production
CONTROL
• Integrated parasite management
• Treat only when necessary
• Treat only those animals that need it
INTEGRATED PARASITE
MANAGEMENT
NON-CHEMICAL
CHEMICAL
• Host immunity
• Proper use of anthelmintics
• Kidding and weaning
management
• Including Targeted Selected
Treatment (TST)
• Nutritional management
• Pasture and grazing
management
• Genetic selection
HOST IMMUNITY:
GOATS VARY IN THEIR
SUSCEPTIBILITY TO PARASITES
MOST SUSCEPTIBLE
• Kids, kids, kids
– Weanlings
– Early weaned kids
– Spring born kids
– Late-born kids
– Artificially reared kids
• Periparturient does
– High producing does
– Yearling does
• Geriatric goats
LESS (BUT STILL) SUSCEPTIBLE
• Mature bucks
• Dry does
• Pet goats
PASTURE AND GRAZING
MANAGEMENT
• Grazing ‘clean’ or ‘safe’ pastures
– not been grazed by goats/sheep ~6 m
– pasture fields – hay/silage crop has
been removed
– pasture fields which have been
rotated with field crops
“Safe” pastures
– pastures than recently established or
renovated by tillage
• Alternate/mixed grazing
Mixed grazing
16
PASTURE AND GRAZING
MANAGEMENT
• Browsing
• Alternative forages
– Tanniferous and bioactive forages#
• Legumes & herbs - high in condensed tannins
• Delayed grazing
• Night penning
• Zero grazing
(dry lot feeding)
Bird's-foot-trefoil
# Marley, et
Chicory
al, 2003. The effect of birdsfoot trefoil (Lotus corniculatus) and chicory (Cichorium intybus) on parasite intensities and performance of
lambs naturally infected with helminth parasites. Vet. Parasitol. 112, 147-155.
TARGETED SELECTIVE
TREATMENT (TST)
WHAT IS IT?
• Only treating animals that
require treatment or only
treating animals that would
benefit from treatment.
WHAT DOES IT DO?
• Slows drug resistance;
– Reduces number of treatments
– Increases refugia
• Identifies resistant and susceptible
animals for selection purposes.
TST: DECISION-MAKING TOOLS
Faecal egg
counts
Dairy Goat Body Condition Scoring: https://www.youtube.com/watch?v=FC0u1j06y5Y.
Check Point
Observation
Possibilities
1. EYE
Anemia
1-5
(FAMACHA© card)
Barber pole worm (Haemonchus)
Liver fluke
Hook worms
Other worms and causes
2. BACK
Body condition score
1-5
(BCS card)
Brown stomach worm (Teladorsagia)
Bankrupt worm (Trichostrongylus)
Nodular worm
Other worms and causes
3.TAIL
Fecal soiling
(1-5)
Dag score card
4. JAW
Soft swelling
“Bottle jaw”
1-5
5. NOSE
Discharge
1-5
5. COAT
Coat condition
1-3
Brown stomach worm (Teladorsagia)
Bankrupt worm (Trichostrongylus)
Coccidia (Eimeria)
Nodular worm (Oesophagostomum)
Other worms and causes
Barber pole worm (Haemonchus)
Coccidia (Eimeria)
Liver fluke
Hook worms
Other worms and causes
Nasal botfly
Lungworms
Pneumonia
Other causes
Barber pole worm (Haemonchus)
Brown stomach worm (Teladorsagia)
Bankrupt worm (Trichostrongylus)
Coccidia (Eimeria)
External parasites
Other causes
IRISH SURVEY
• Faecal samples
• 11 farms
– 5 kids
– 15 adult
FARMING ENTERPRISE
• 11 responses
Dairy
Cheese
Meat
Mixed
Other
Other
14%
Dairy
29%
Mixed
7%
Meat
14%
Cheese
36%
PERCENTAGE FARMS
POSITIVE
Percentage farms positive
Moniezia
Strongyloides
Nematodirus
Gastrointestinal Nematodes
Eimeria
Lungworms
Dicrocoelium
Calicophoron
Fasciola
Skrjabinema
Trichuris
0
10
20
30
40
%
50
60
70
80
90
100
PERCENTAGE POSITIVE BY
AGE
Percentage Adult and Kids positive
Moniezia
Strongyloides
Nematodirus
Gastrointestinal
Nematodes
Eimeria
Lungworms
Dicrocoelium
Calicophoron
Fasciola
Skrjabinema
Trichuris
0
10
20
30
40
Kids %
50
Adults %
60
70
80
90
100
FAECAL EGG COUNT
Faecal egg count
Faecal egg count
Nematodirus
Lungworms
Gastrointestinal
Nematodes
Calicophoron
Fasciola
Skrjabinema
Eimeria
Trichuris
0
50
100
150
200
eggs per gram
MAX
MIN
250
300
0
2000
4000
eggs per gram
6000
8000
MAX
ZERO GRAZING AND
PARASITE MANAGEMENT
• 5 farms reported zero grazing
Coccidia
Rumen fluke
Liver fluke
GIN
Treat Does
Treat Kids
0
0.5
1
1.5
2
2.5
Number of farms
3
3.5
4
4.5
5
ANTHELMINTIC USE
DOSAGE
DRUG CLASSES USED
Number of farms
3
1-BZ
2-LV
3-ML
2
33%
50%
1
0
1
1.25
1.5
2
Sheep dose
• No wormers licensed for goats in Ireland
• Goats metabolise drugs differently from sheep
• Evidence to suggest higher dose rate required
• 1-BZ & 3-ML – 2x sheep dose
• 2-LV – 1.5x sheep dose (toxicity reported)
17%
ANTHELMINTIC RESISTANCE
Ability of worms in a population to survive drug treatments that generally are
effective against the same species/stage at same dose rate
ANTHELMINTIC RESISTANCE
QUANTIFIED (SHEEP)
100
29
90
43
80
% of farms
70
71
60
50
71
40
56
30
20
29
10
0
BZ
(n = 207)
LEV
(n = 105)
Drug class
ML
(n = 212
Efficacy: 95 - 100
Efficacy: ≤94
DEVELOPMENT OF RESISTANCE
• Heritable trait
• Inevitable consequence of good nematode control
• Why?
– Drug eliminate the susceptible genotypes
– Resistant parasite survive  reproductive advantage and pass on their
“resistant” alleles
– Gradual build-up
S S
S S S
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S S
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S S S
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R
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S R
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R S
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R S
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CONTRIBUTING FACTORS ASSOCIATED
WITH AR
• High treatment frequency
• Under dosing
•
Incorrect calibration of equipment
•
Underestimate live weight
• Treatment strategies that minimize in refugia population
•
Treat all animals
•
Treat when few larvae are on pasture
•
–
Early in grazing season
–
Treatment at ecological critical times
Treat & move to “clean” pasture
• Lack of quarantine treatments
•
Animal movement disperses resistant worms
• Worm/fluke combinations & ML for ectoparasites at inappropriate times
Refugia = The helminth population not under selection pressure of drug treatments
HELMINTH CONTROL: BEST
PRACTICE
• Quarantine treatment on arrival
–
Treat with 2 effective drug classes
–
48 hours
–
Turned onto contaminated pasture
• Correct drench technique & right dose
• Test for resistance
• Examine control strategy
–
reduce treatments
• Reduce dependence on anthelmintics
–
Grazing management, use resistant rams
• Only treat when necessary
–
Pathophysiological markers, FEC, Performance indicators
• Use most appropriate anthelmintic
–
Preserve new generation anthelmintics
• Preserve susceptible worms
–
Leave some (10-15%) sheep untreated
–
Treat few days before moving
http://www.nationalsheep.org.uk/