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Endoparasites
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- 1How can parasites harm their host?Numbers of parasites
Competition for nutrients
Feeding habits
Site of infection - 2How do parasites avoid destruction inside host?Evading immune system
Suppress/ Manipulate the host immune response - 3Worms in the abomasum of sheepHaemonchus contortus
Teladorsagia circumcincta
Trichostrongylus axei - 4Worms in the small intestine of sheepNematodirus spp
Trichostrongylus spp
Cooper spp - 5Worms in large intestine of sheep and cattleChabertia spp
Oesophagostomum spp
Trichuris spp - 6—Teladorsagia circumcincta
1cm
slender, pinky brown
Cervical papillae
Males have bursa + spicules - 7Life cycle of trichostrongyle sppDirect life cycle
Adult worms in abomasum mate
Females produce eggs
Eggs develop in faeces (L1-L3)
L3 released from faces by rain
L3 = infective
L3 eaten + reaches abomasum then burrows into gastric glands
Develops (L3-L5)
L5 emerge into lumen of abomasum
Maturation into adult worm
PPP 3 weeks - 890umTrichostrongyle eggs
Barrel shaped
Undifferentiated - contain undeveloped morula
- 9Pre-patent period (PPP)Time taken from the time of infection to the detection of eggs in the faeces
- 10A patent infectionAn infection that can be detected
- 11How does teladorsagia circuncinta cause disease?Associated with large numbers of developing larva (40,000+)
Damage caused by developing larvae in gastric glands + emerging L5
Parietal cells replaced by undifferentiated epithelial cells
Loss of acid production
Inc in abomasal pH
Loss of bacteriostatic effect
No conversion of pepsinogen to pepsin
Inc permeability of mucosa - 12Clinical signs of PGEProfuse watery diarrhoea
Weight loss
Inappetance
Dehydration
Death - 13Sub-clinical signsPoor weight gain
Reduced appetite +food intake
Loss of plasma proteins into GI tract - 14What sheep are usually affected by PGE ? and when ?Type 1
First season grazing lambs
Mid summer onwards
Type 2
Due to hypobiosis of L3 in autumn
Simultaneous emergence of L5 in
Yearling animals
Late winter - 15HypobiosisThe arrested development of larvae within the host - in response to a trigger received by the free living L3
- 16What triggers hypobiosis in teladorsagia circumcincta ?Drop in ambient temp in autumn
- 17Species that contribute to PGETeladorsagia circumcinta
Trichostrongylus spp
Cooperia spp
Exceptions !
Nematodirus battus
Haemonchus contortus - 180.5cmTrichostrongylus spp
Diagnostic feature = excretory notch
- 19Site of trichostrogylus axei infectionAbomasum
- 20Clinical signs of trichostrongylus axei infection.Can cause PGE - so same as PGE
Weight loss/ Poor weight gain
Poor skeletal growth
BLACK SCOUR - 21Trichostrongylus spp life cycleSimilar to t. circumcincta
Hypobiosis
L3 overwinter - 22Trichostrongylus spp pathogenesisLarvae develop deep in mucosa
Sub epithelial tunnels
Villous atrophy
Oedema
Haemorrhage
Diarrhoea - 23When is disease caused by trichostrongyle spp usually seen ?Autumn disease of store lambs
Climate change!- seeing in summers and after mild winters, Severe disease in winter spring. - 24—Cooperia spp
"Watch spring" worm
Cephalic vesicle
Male has short stumpy spicules
- 25Pathogenesis of cooper sppMild pathogen
Can affect weight gain
Heavy infections
Catarrhal enteritis
Villus atrophy
Oedema of intestinal mucosa - 26Worms in abomasum of sheep and cattleHaemonchus contortus
Teladorsagia circumcinta
Trichostrongylus axei - 27Worms in the small intestine of sheep and cattleNematodirus spp
Trichostrongylus spp
Cooperia spp - 28Worms in the large intestine of sheep and cattleChabertia spp
Oesophagostomum spp
Trichuris spp - 29Sources of infection of PGEPPR in ewes
Hypobiosis of larvae - 30Over dispersionSmall proportion of the host population carries the majority of the parasite population
20% of population sheds 80% of the eggs - 31PPRPeri-parturient rise
Reduced immunocompetence around parturition
2w before lambing, 6w after lambing - 32YEAR WITH T.circYEAR WITH T.circ
- 33SpringOverwintered L3 on grass
Ewes turned out w lambs
Ewes contaminate pasture. (PPR) - 34May/JuneEwe = main source of infection
Eggs shed on pasture start to develop
Lambs start to graze + ingest overwintered L3
Eggs shed from lambs onto pasture - 35June/julyTemp sarts to inc so egg development speeds up
Large numbers of L3 appear on pasture - 36Aug/SeptDisease seen in lambs
- 37—Nematodirus baths
2cm long
Often found in tangled groups of worms like cotton wool
Cephalic vesicle
Males have long thin spicules
Females have large eggs within uterus
- 38Where is nematodirus battus found in the host?Small intestine
- 39—Nematodirus battus Eggs
L1-L3 develops within the egg
- 40N.battus life cycleUnembryonated eggs shed in faeces
L3 develops in egg
L3 hatches
(L3 infective stage)
L3 ingested
L3-L4 in SI lumen
L4 burrows into mucosa of SI
L4-L5
L5 emerges and adults mature in SI
PPP 15d - 41Pathology of N.battusDeveloping L5 destroy the mucosa
Catarrhal enteritis
Villous trophy
Fluid + Nutrient absorption disrupted
2000 worms can cause clinical disease - 42Clinical sigs of N.battusSudden outbreaks of acute watery diarrhoea
Inappetence
Dehydration (Thirsty!)
Abdominal pain
Weight loss - 43When is disease caused by N.battus?Lambs around 4-12weeks
Often starts in PPP - 44How many eggs per gram indicate its a heavy infestation of N.battus?Mean WEC>500epg
- 45Hatching requirements of N.battusExposure prolonged period of chill
Exposure to mean day/night temp of 10degrees C - 46For N.battus disease to occur hatching must coincide wPresence of susceptible lambs
Old enough to graze
Before age immunity develops - 47Are ewes a large source of infection?No
Strong acquires immunity therefor ewes not affected
Lamb to lamb cycle! - 48How do you control N battusGrazing management
Prophylactic Tx (NOT susceptible to injectable MLS) - 49Changing epidemiology of N.battusMoe outbreaks in autumn due to eggs passed that summer hatching w/o need for chilling and warming
- 50—Haemonchus contortus
Large 3cm
Cervical papillae
White ovaries wrapped around gut (Barbers pole)
Assymetrical dorsal lobe
- 51Life cycle of haemonchus contortusTypical trichostrongyle
PPP - 3wks
Larvae develop in mucosa
Adults are blood feeders
Hypobiosis
L3 don't survive winter in UK - 52Pathogenesis of H.contortusAdults feed on blood
Erosion of abomasal wall
Severe haemorrhage gastritis - 53Clinical signs of H.contortusSevere anaemia
Oedema
Weight loss - 54Are ewes a source of infection of haemonchus contortus?Yes - Ewes are the main source of pasture contamination
- 55When is disease caused by H.contortus seen?Late summer
- 56Haemonchus controlBZs white drenches
LEV/PYR yellow drenches
MLs clear drenches
AAD -monepantel
Derquantel + Abamectin
Vaccine? - 57Dx PGEClinical signs -Diarrhoea, poor weight gain/weight loss
Season - August/Sept - 58Nematode species that cause PGET.circumcincta
Trichostrongylus spp
Cooperia spp
H.contortus - 59Control - Pre parasitic stagesFaecal removal - not practical for ruminant systems
Grazing management
Biological control - nematode trapping fungi - 60Control - parasitic stagesGenertically mediated host resistance
Anthelmintics vaccination - 61Control of PGEQuarantine incoming animals
Test for anthelmintic resistance
Correct administration of drugs
Only use drugs were necessary
Choice of anthelmintic
Preserve refugia population - 62Management of resistant parasitesDrug prophylaxis
Clean pasture
Safe pasture
Rotation w crops/other stock - 63Clean pastureNon grazed by sheep for previous 12 m
- 64Safe pastureUsed the previous year, but safe beginning on June
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- (Parasitology ) Vet Med 2 Fichas sobre Endoparasites, creado por Alice Butterworth el 12/12/2018.
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- Alice Butterworth
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