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VMS 2003 > Parasitic Gut Diseases I > Flashcards

Parasitic Gut Diseases I Flashcards

1
Q

What is the typical lifecycle of gut nematodes in ruminants?

A
  1. Adults mate in the GIT
  2. Eggs are then passed out in the faeces
  3. Eggs then hatch out and develop into L3 larvae
  4. Larvae are ingested, and 2 moults occur
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2
Q

What are the important sheep abomasum parasites?

A
  • Haemonchus contortus
  • Teladorsagia circumcinta
  • Trichostrongylus axel
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3
Q

What are the important small intestine sheep parasites?

A
  1. Nematodirus battus
  2. Trichostrongylus spp.
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4
Q

What is the important cattle abomasum parasite?

A

Ostertagia ostertagi

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5
Q

What is the important small intestine cattle parasite

A

cooperia oncophora

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5
Q

What are the key notes for osteratagia ostertagi?

A
  • Has a worldwide distribution
  • larvae develop in the gastric glands of the abomasum and mature on the mucousal surface
  • The prepatent period is 3 weeks
  • requires up to 2 grazing seasons to acquire immunity
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6
Q

What is the pathogenesis for type 1 bovine ostertagiosis?

A
  • Occurs in calves in the first grazing season
  • they ingest larvae and then it develops 3-4 weeks later
  • Occurs from mid July
  • there is profuse watery diarrhoea (green), weight loss, mortality is rare if it is treated early
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7
Q

What is the pathogenesis for Type II bovine ostertagiosis?

A
  • Occurs in yearlings in the late winter/ spring following the first grazing season
  • the larvae are ingested in the autumn and then arrest *hyperbiosis *
  • larvae emerge together in late winter months
  • has a high mortality rate
  • diarrhoea, anorexia and thirst
  • poor treatment response
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8
Q

What is hyperbiosis?

A

development arrests around the L3/L4 stage
metabolic rate decreases

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9
Q

What are the initiating factors of hypobiosis?

A
  • Host immune responses
  • seasonal influences
  • overcrowding
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10
Q

What is the biological importance of hypobiosis?

A
  • allows them to survive in hostile environmental conditions
  • larvae may be less susceptible to some antithelmintics
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11
Q

What does ostergiosis do to the body?

A

There is a loss of the parietal cells in the abomasum
This increases the pH of the abomasal contents
This causes a failure to convert pepsinogen to pepsin
therefore protein digestion is impaired and there is a bacterial accumulation in the GIT
you also dont have the acid ph preventing bacterial growth

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12
Q

What is the epidemiology of ostertagiosis?

A

1) Overwintered L3 infect calves after turn-out → sub-clinical infection, eggs deposited
2) Overwintered L3 die during spring
3) Eggs develop to L3, become infective by mid-June, can → type I disease in July-Oct
4) As temps↓ larvae arrest at EL4. By late autumn calves can harbour 1000s of EL4
5) Maturation of EL4 larvae in winter & early spring → type II disease

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13
Q

What is the epidemiology of ostertagiosis in spring-calving herds?

A
  • Immune adults graze alongside calves & ingest larvae
  • Little ostertagiosis, egg production by adults is low
  • Overwintered L3 die before suckling calves ingest much grass
  • Low numbers of L3 available on pasture later in the year
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14
Q

What is the epidemiology of autumn/ winter calving?

A
  • Ostertagiosis in following grazing season if grazed on contaminated pasture &
    insufficient immunity as young calves
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15
Q

What does cooperia oncophora cause?

A
  • inappetence/ poor weight gain in calves
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16
Q

Where do cooperia oncophora develop?

A

The adults develop on the surface of the intestinal mucosa

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17
Q

What are the four main gut nematode diseases in sheep?

A
  1. Nematodirosis
  2. Ostertagiosis
  3. Haemonchosis
  4. Trichostrongylosis
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18
Q

What are the key features of nematodirosis?

A
  • Important in lambs
  • Development to L3 takes place in eggshell
  • Hatching requires prolonged chill, then mean temp >10oC (late spring)
  • L3 larvae penetrate mucosa of small intestine, 2 moults then enter lumen
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19
Q

What is the pathogenesis of nematodiresis?

A
  • Due to larvae
  • It causes severe damage to the villi and erosion of the mucosa -> villous atrophy and fusion
  • there is an impaired ability of the intestine to exchange fluids and nutrients
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20
Q

What are the clinical features and diagnosis of nematodiresis?

A
  • Yellowy-Green Diarrhoea
  • dehydration and inappetence, reduced growth rate
  • mortality is high if left untreated
21
Q

What is the unique epidemiology of nematodiresis transmission?

A
  • Eggs survive on pasture for long periods
  • Lots of L3 appear on pasture at same time
  • Disease outbreak if hatching coincides with grazing of lambs (often May &
    June)
  • Cool, wet summers prolong L3 survival – may get outbreaks in older lambs later
  • Lamb-to-lamb transmission, one generation of parasites each year
  • Adult sheep play little role in transmission
22
Q

What causes ostergiosis in sheep?

A

Teladorsagia circumcincta

23
Q

What are the clinical signs of ostertagiosis in sheep?

A

weight loss & intermittent diarrhoea, poor protein & fat deposition,
particularly in lambs

24
What is the epidemiology of ovine ostertagiosis?
* Highest larval numbers on pasture July-Oct * Derived from: 1. Eggs passed by ewes during periparturient period (2 wks prior to – 6 wks after lambing) 2. Eggs passed by lambs after ingesting overwintered larvae 3. Eggs passed by lambs infected in July * If ingested prior to Oct, larvae develop to adults → type I disease * Later ingestion, larvae arrested, may get type II disease
25
What causes Haemonchosis?
Haemonchus contortus
26
What is the appearance of Haemonchus?
In females it has a "barbers pole" appearance
27
What do the Haemonchus contortus larvae do?
Larvae exsheath in rumen & moult 2x in gastric glands
28
What does acute haemochiosis look like? | over 2000 worms
* Anaemia, ↓↓ packed red cell volume, loss of iron & protein to GI tract * Oedema e.g. submandibular & ascites * Inappetence, lethargy, dark coloured faeces, falling wool * Mortality
29
What does chronic haemonchosis look like? | 100s of worms
Continual loss of blood -> weight loss, weakness and inappetence particularly in areas where the pasture is deficient in nutrients
30
What is the epidemiology of haemonchosis?
* Larval development depends on high temp and humidity * High egg output so rapid pasture contamination
31
What is the epidemiology of haemonchosis in temperate areas
* Ewes deposit eggs in spring, L3s ingested by ewes & lambs in early summer, most arrest development → disease following spring * Some do not arrest → disease in lambs in late summer
32
What parasites cause Trichostrongylosis in sheep?
* Trichostrongylus axei (abomasum) & Trichostrongylus spp. (small intestine)
33
What are the clinical signs of Trichostrongylosis?
* Rapid weight loss & diarrhoea (dark, foul-smelling) * Inappetence & poor growth rates (lower levels of infection)
34
What is the epidemiology of Trichostrongylosis?
* Eggs/L3 larvae survive in environment under adverse conditions * Larvae on pasture ↑ in late summer/autumn → clinical problems in lambs in Nov-Dec * Occasionally disease in spring due to survival of eggs & L3, also hypobiosis
35
What do you need to consider when diagnosing gut nematodes?
* Host species * Host age * Season * Grazing history * History of parasite infection * Clinical signs
36
What is the difference between battus and strongyle eggs?
N.battus eggs are 160 μm long, Strongyle eggs are ~80 μm long
37
What are some other tests you can do for parasites?
* Plasma pepsinogen levels * Anti-Ostertagia ostertagi (T. circumcincta) antibody levels can measured in milk * Blood haemoglobin, packed cell volume & red blood cell count ↓ in haemonchosis
38
What causes rumen fluke?
paramphistomes e.g. Calicophoron daubneyi
39
What does rumen fluke cause?
Disease - heavy infestations of immature fluke in intestine * Diarrhoea, anorexia, anaemia, ill-thrift
40
Where are rumen fluke parasites found?
* Young flukes in duodenum, adults in forestomachs
41
What is the lifecycle of rumen fluke?
1. Eggs 2. Miracidia 3. galba trunculata (snail) 4. cercariae 5. metacercariae
42
What are Moniezia benedeni & M. expansa?
* Cestode parasites – tapeworms * they are adults in the small intestine * not highly pathogenic but a solid mass of tapeworms could occlude the intestinal lumen in lambs
43
What are tapeworms common in?
They are common in calves and lambs, there is seasonal fluctuation due to active periods of forage mites
44
What is the lifecycle of the Moniezia species?
* Definitive host is infected when it eats an infected mite, adult tapeworm in the hosts small intestine may be several metres long * eggs then pass through in faeces * eggs are ingested by orbitid mites * Cysticercoid develops in mite
45
What is the SCOPS principle?
* Make sure that treatment is fully effective * Reduce reliance on anthelmintics using management options and monitoring * Avoid bringing in resistant worms by following a robust quarantine protocol * Minimise selection for worms that are resistant to anthelmintics when treating sheep
46
How can farmers impliment the SCOPS principle?
Make sure that the treatment is fully effective * Dose at rate for heaviest sheep (weigh biggest sheep!!) * Calibrate drench gun * Make sure correct dosing technique is used * Chose the right product for the parasites on farm * Test for resistance (Faecal Egg Count Reduction Test)
47
What are some parasite management options?
o Pasture risk assessment o Wean lambs at 12 weeks and move to less contaminated grazing o Grazing by mature ewes – reduces contamination on pastures o Mixed grazing (sheep and cattle) and reduced stocking densities o Rotational grazing
48
How can nutrition assist in the prevention of parasites?
* Sheep under nutritional stress less able to withstand challenge from internal parasites Bioactive forages (chicory, birdsfoot trefoil and sainfoin)
49
What do Haemonchosis Contortus Develop?
a 'piercing lancet' this allows them to take blood from mucousal vessels

VMS 2003 (33 decks)

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