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Veterinary Year 3 > Parasitology > Flashcards

Parasitology Flashcards

1
Q

What are the three main groups of parasites?

A

Helminths - consisting of nematodes (round worms) and platyhelminths (cestodes and flukes)

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2
Q

What 2 groups can nematodes be split into ?

A

Bursate and non-bursate

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3
Q

What defines a nematode as a bursate nematode?

A

Male worms have an inflation of the cuticle at the posterior end along with spicules which aids reproduction

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4
Q

Name some distinguishing physical features of trichostrongyles

A
  • small buccal cavity with an obvious pharynx

- have cuticular decoration used for identification

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5
Q

Name some key facts about trichostrongyles

A
  • direct life cycles
  • infective stage L3
  • bursate nematodes
  • non-migratory
  • Lay typical oval undifferentiated eggs
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6
Q

Describe key points in the life cycle of trichostrongyles

A
  • direct
  • eggs laid in gut lumen and excreted in faeces
  • eggs hatch on pasture and progress from L1 through to infective L3
  • L3 ensheathed in L2 cuticle is ingested
  • L3 converts to L4 and L5 in the GI mucosa
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7
Q

What is the PPP?

A

Pre-patent period = the time taken from first infection to the detection of infection (eggs in faeces)

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8
Q

Name some key facts about strongyloidea

A
  • well developed buccal cavity with teeth
  • direct life cycles
  • L3 infective stage
  • bursate nematodes
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9
Q

Name some parasites belonging to the strongyloidea family

A

strongylus
oesophagostomum
cyathostomins

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10
Q

Name some parasites that belong to the trichostrongyloidea family

A

ostertagia
trichostrongylus
cooperia
nematodirus

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11
Q

Name some parasites that belong to the ancylostomatoidea family

A

Ancylostoma

uncinaria

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12
Q

Name some parasites that belong to the metastrongyloidea

A

metastrongylus
muellerius
angiostrongylus
filaroides

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13
Q

What is the common name for strongyloidea?

A

hook worms

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14
Q

Describe some general features of hookworms

A
  • hooked shape
  • large buccal cavity with cutting plates
  • migratory
  • infective L3
  • bursate nematodes
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15
Q

What is the common name for Metastongyles

A

Lung worm

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16
Q

Name some parasites in the ascaroidea family

A
  • ascaris
  • toxocara
  • toxascaris
  • ascaridia
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17
Q

Name some parasites in the filarioidea

A
  • dirofilaria

- onchocerca

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18
Q

Name some parasites in the trichuroidea family

A
  • trichuris

- trichinella

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19
Q

Describe some general features of Metastrongyles

A
  • common name - lungworm
  • adults found in lungs and associated vessels
  • bursate nematodes
  • eggs laid in lungs which hatch into L1 and are coughed up, swallowed and excreted in faeces
  • Indirect life cycles - intermediate host usually a mollusc
  • L1s have a notched tail for ID
  • Infective stage = L3
  • once ingested migrates via the lymph nodes to the lungs
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20
Q

Name the bursate nematodes

A
  • metastrongles - lung worms
  • Trichostrongyles
  • strongyles
  • cyathostomines
  • Ancylostomas - hook worms
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21
Q

Name the non-bursate nematodes

A
  • Ascarids
  • Filarial nematodes - heart worm
  • Trichuris
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22
Q

Describe the general features of Ascarids

A
  • Toxocars and toxascaris species
  • large white worms
  • non-bursate
  • adults found in small intestine
  • have highly environmentally resistant eggs
  • infective stage = L2 in egg
  • direct life cycles
  • can involve paratenic and transport hosts
  • hepato-tracheal migration occurs where the larvae are then coughed up and swallowed
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23
Q

What is a patent infection

A

one that can be detected

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24
Q

What is a paratenic host

A

not essential for the life cycle, parasite development can occur within this host

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25
Q

What is a transport host

A

not essential for the life cycle, involved in transporting the parasite in it’s current stage, no development occurs

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26
Q

What is an intermediate host

A

essential for the parasite life cycle, development occurs in this host

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27
Q

Describe general features of filarial nematodes

A
  • adults reside in blood vessels, ligaments, tendons and particularly inhabbit the cardiac region
  • can cause major problems
  • non-bursate nematodes
  • adults are large
  • have indirect life cycles, intermediate host often blood or tissue feeding flies
  • females lay live L1s which travel in the blood stream or migrate to the skin
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28
Q

What are the main diagnostic tests for nematode parasites?

A
  • faecal egg count - sometimes sensitivity is low and will only detect a patent infection
  • molecular tests and immunological tests - varying sensitivity and specificity depending on the parasite
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29
Q

What is the best program for worming in horses and why?

A

Targeted worming programs are the most effective as not all horses need treating all the time, a few individuals will have most of the worm burden and by not treating everything you are reducing the likelihood of resistance to anthelmintics developing. This will likely reduce parasitic disease and transmission of the parasite.

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30
Q

How can horses be targeted for treatment?

A

Use faecal egg counts and treat the individuals with an egg count above 200 eggs/gram as these will be the major culprits for pasture contamination
Faecal egg counts should be done every 6-8 weeks when conditions are favourable for transmission - warm and wet

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31
Q

What is interval dosing

A

treating at regular intervals based on the egg reappearance period

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32
Q

What is strategic dosing

A

treating specifically based on epidemiology

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33
Q

What is targeted dosing

A

Treating at specific times based on epidemiology and on all horses having faecal egg counts

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34
Q

What adulticidal treatment can be used for large strongyles in horses

A

benzamedazoles
moxidectin
ivermectin
pyrantel

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35
Q

What adulticidal reatment can be used for small strongyles in horses

A

moxidectin
ivermectin
pyrantel
resistance seen against benzamidazoles

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36
Q

what larvicidal treatment can be used for treating large strongyles in horses

A

ivermectin

moxidectin

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37
Q

What larvicidal treatment can be used for treating small strongyles in horses

A

moxidectin

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38
Q

How are tapeworms treated in horses

A

double dose of pyrantel or single dose of praziquantel

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39
Q

Describe large strongyles

A
  • direct life cycles
  • infective L3
  • larvae are migratory - end up in cranial mesenteric arteries
  • can cause blockage and severe colic
  • susceptible to most anthelminticss
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40
Q

Describe cyathostomins

A
  • direct life cycle
  • capable of hypobiosis - stop maturation over winter and remain burried in mucosa
  • infective L3
  • no strong immunity develops to this parasite
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41
Q

Describe the basic Anoplocephala characteristics in horses

A
  • common name = tapeworm
  • adults found in small intestine
  • obligatory indirect life cycles
  • intermediate stage in all tapeworms is called metacestode stage
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42
Q

Describe the basic characteristics of Anoplocephala perfoliata

A
  • affects horses
  • adults at the ileocaecal junction
  • short, broad segmented worms
  • intermediate host = orabatid mite
  • intermediate stage = cysticercoid
  • eggs are D shaped with a thick shell
  • normally tapeworms are relatively non-pathogenic but this one causes GI complications e.g. colic, obstruction, inflammation, ulceration and intussusception
  • immunity doesn’t develop well with this parasite
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43
Q

Describe the life cycle of Anoplocephala perfoliata

A
  • adults lay eggs into lower body segments which break off to form proglottids which are passed in faeces
  • the orabatid mite ingests the eggs where they develop into cysticercoid cysts containing larvae
  • the mites are eaten by the horse and the parasite emerges in the gut and develops into the adult worm
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44
Q

Describe the life cycle for parascaris equorum

A
  • affects horses
  • eggs passed in faeces and develop in the egg n the ground to L2 - infective stage
  • the larvated eggs are eaten where they hatch in the gut and migrate to the liver and then to the lungs where they become L3
  • the L3 are coughed up and swallowed where they develop to adulthood in the small intestine
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45
Q

Describe the pathogenesis and control of pasascaris equorum

A
  • typically affects foals as good immunity once exposed
  • causes weight loss, unthriftiness and a transient cough , obstruction can sometimes occur
  • treat with Bzs as resistance reported with ivermectin
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46
Q

Describe the general feaures of oxyrus equi

A
  • common name - pinworm
  • inhabbits large intestine
  • females lay eggs on skin outside the rectum - anal rust
  • the eggs around the anus cause pruritus
  • eggs dry and fall off contaminating the environment and develop into L3 which are ingested to cause infection
  • control by keeping good hygiene and washing the anus
  • can see adults passed in faeces as small white worms with pointed tails
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47
Q

Name the 2 main types of hook worm

A

uncinaria stenocephala

ancylostoma caninum

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48
Q

Describe the main characteristics of uncinaria stenocephala

A
  • affects dogs, foxes act as a reservoir
  • adults are small and live in the small intestine
  • the head and neck is curved into a hook shape and they have a large buccal cavity with cutting plates to feed on blood and mucosa
  • infective sage is L3
  • Direct life cycle
  • lay typical strongyle like eggs
  • not highly pathogenic - can see anaemia, weight loss, lethargy and sometimes diarrhoea with heavy infections but the main problem is pedal dermatitis from percutaneous infection
  • diagnosisvia clinical signs and eggs in faeces
  • control via regular worming with Bzs or MLs - also avoid earth compounds
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49
Q

Describe the life cycle of uncinarai stenocephala

A

3 main routes of infection:

  1. no migration L3 ingested and goes into the gut to develop
  2. L3 is ingested and undergoes migration to the lungs - moult to L4 in the blood stream and is coughed up and swallowed Can also migrate through the buccal mucosa if they get stuck in the mouth
  3. percutaneous infection - L3 bury into the skin between the footpads, they begin migration but often trigger and immune response and are killed
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50
Q

Describe the general features of ancylostoma caninum

A
  • affects dogs and foxes
  • seen in imported dogs
  • migration more common in this species than uncinaria stenocephala
  • Also capable of percutaneous infection
  • direct life cycle
  • highly pathogenic - voracious blood feeders
  • cause anaemia, weight loss, lassitude, poor condition and sometimes diarrhoea
  • treat and diagnose same as uncinaria stenocephala
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51
Q

Describe the general features of spiruida

A
  • heart worm order
  • large thin worms
  • eggs hatch in utero or females give birth to live young
  • indirect life cycles - utilise invertebrates
  • usually adults parasitise tissues other than the gut
  • most significant family = filaria
52
Q

Describe the general features of dirofilaria immitis

A
  • also known as the true heart worm
  • very rare zoonosis
  • transmitted by mosquitoes
  • can also affect cats and ferrets although less severe pathogenesis seen
  • L1 infects the mosquito and is known as microfilariea
  • adults very large and inhabit pulmonary arteries and the right ventricle
  • L3 = infective stage
53
Q

Describe the life cycle of dirofilaria immitis

A
  • adults give birth to live L1 (microfilariea) which pass into the bloodstream and are picked up by mosquitoes when the animal is bitten
  • within the mosquito the L1 develops into L2 then L3
  • The L3 migrates to the salivary glands in the mosquito and is inoculated back into the animal
  • the L3 migrates to the subcutaneous and subserosal tissues then moults to L4
  • the L4 migrates to the abdomen where they moult to L5
  • The L5 penetrate the larger vessels or enter the blood stream and become trapped in the pulmonary artery
54
Q

What is the clinical presentation and treatment of dirofilaria immitis

A
  • disease usually associated when large numbers of adults are present
  • chronic disease often presents with exercise intolerance, chronic cough, dyspnoea, lipothymia, anorexia, right side heart failure, cachexia and respiratory distress
  • in small dogs it can present with acute caval syndrome intravascualar haemolysis and haemoglobinuria - requires immediate surgery to remove worms
  • in cats see digestive or neurological signs which can also be in conjunction with pulmonary symptoms
  • sudden death in cats is more common
  • Diagnosis via the knott test - detects microfilariae in blood, however often gives false negatives and doesn’t detect male only infections
  • MLs used as prophylaxis
  • care when treating a worm burden as can get emboli of dead worms - restrict exercise for 30-40 days post treatment
55
Q

Describe the features of dirofilaria repens?

A
  • parasite of dogs, cats and wild carnivores
  • adults found subcutaneously in nodular swellings
  • much more commonly zoonotic
  • microfilariae can be distinguished from other species by size, morphology and staining with acid phosphatase
56
Q

Describe the general features of Toxocara Cati

A
  • same as toxocara cannis
  • some differences in life style:
    * no migration if paratenic host is ingested
    * no transplacental transmission
    * no migration if transmitted via the mammary
    * Migration does occur if L2 eggs are ingested - hepato tracheal migration
  • treat with MLs or BZs
57
Q

Describe the general features of toxascaris leonine

A
  • can infect dogs and cats
  • no migration occurs
  • no zoonotic risk
  • can be infected by ingestion of paratenic host or with L2 eggs
  • no transplacental or transmammary transmission
58
Q

Describe the Pathogenesis, diagnosis and control of Toxocara cannis

A
  • asymptomatic in most adults
  • heavy worm burdens in puppies can result in pot bellies, poor weight bain and intestinal obstruction
  • no diarrhoea seen
  • diagnosis via clinical signs and eggs in faeces
  • give Bzs or MLs to control intestinal stages
  • give fenbendazole to pregnant bitches daily from 42 days gestation
  • worm puppies regularly at 2,4,6 and 12 weeks and 6 months followed by every 3- 6 months after that
59
Q

Describe the life cycle of toxocara cannis

A
  • adults in the small intestine lay eggs and shed in faeces
  • L2 within the egg is the infectious stage and can be transmitted via several routes:
    1. transmammary - L2 present in milk
    2. Transplacental - L2 migrate from the gut and become arrested in skeletal muscles. They are re-activated in the last trimester of pregnancy where they cross the placenta and infect the foetus
    3. In dogs less than 3 months the eggs are ingested, hatch in the small intestine and migrate to the liver, then to the lungs to become L3, they are then coughed up and swallowed and become L4 and L5 in the small intestine
    In dogs older than 3 months the L2 migrate but become arrested in tissues .
60
Q

General features of metastrongyles

A
  • most have indirect life cycles
  • inhabit the lungs and adjacent blood vessels
  • L1 passed in faeces have kinked tails used for ID
  • Larvae undergo hepatotracheal migration
61
Q

Describe the general features of Angiostrongylus vasorum

A
  • adults like in pulmonary artery and right ventricle
  • intermediate hosts - molluscs,mainly slugs infected by feeding on dog faeces
  • frogs can be a paratenic host
  • younger dogs are at higher risk
  • foxes are reservoir hosts
  • diagnosis via L1 in the faeces or respiratory tract - samples should be repeated as this can be an intermittent process
  • treat with Bzs or MLs
  • Clinical signs - very diverse, lethargy, exercise intollerance, weight loss, respiratory signs, sudden death, coagulopathies, enlarged heart, neurological symptoms
62
Q

Describe the life cycle of angiostrongylus vasorum

A
  • eggs ae released into pulmonary vessels and are carried via the capillaries into the alveoli
  • these are coughed up and swallowed and L1 is passed in faeces and ingested by the mollusc
  • within the mollusc it moults to L2 and L3
  • the mollusc is eaten by a dog and the L3 migrate in the blood stream to the lymph system, heart and pulmonary vessels where they become adults

It is thought that L3 can exist freely and could be released in the slime of the mollusc

63
Q

Describe the basic features of crenosoma vulpis

A
  • affects dogs, foxes act as a reservoir
  • have indirect life cycles
  • adults are slender white worms with spiny cuticular folds
  • intermediate hosts are molluscs - develop from L1-L3
  • adults inhabit the mucosa of the trachea, bronchi and bronchioles
64
Q

Describe the general features of oslerus osleri

A
  • affects dogs
  • has a direct life cycle - untypical of lungworms
  • capable of transplacental transmission
  • adults live in tracheal nodules
  • L1 in sputum is the infective stage
  • causes coughing, tracheobronchitis
  • mostly seen in young dogs
  • diagnosis via nodules in trachea or larvae in faeces
65
Q

Describe the general features of Aelurostrongylus abstrusus

A
  • affects cats
  • adults inhabit lung parenchyma
  • L1 found in faeces - have S shaped tails
  • indirect life cycles - intermediate host is the mollusc
  • paratenic hosts also occur
  • fairly commn, often asymptomatic
  • clinical signs - coughing and respiratory disease
  • treat with fenbendazole
66
Q

Describe the General features of ostertagia ostertagi

A
  • brown worm inhabbiting the GI tract
  • very common small numbers found in most catle
  • inhabits the abomasum
  • bursate nematodes
  • have cervical papillae at the head end used for ID
67
Q

What is the life cycle of ostertagia ostertagi

A
  • direct
  • lay typical strongyle eggs - barrel shaped and undifferentiated
  • adults lay eggs in abomasum which are passed in faeces
  • develop on pasture from L1 - L3
  • L3 is the infective stage and is ingested then buries into gastric glands in the abomasum where it moults to L4 and L5 where it emerges into the lumen
68
Q

Describe the pathogenensis, clinical signs, disease and treatment of ostertagia ostertagi

A
  • disease occurs with large numbers of larvae
  • within the gastric glands are parietal cells secreting HCL these maintain the acidic pH of the abomasum and help convert pepsinogen into pepsin to breakdown proteins.
  • L3 feed on the cell contents in the gland and as they grow damage parietal cells which are replaced by unddifferentiated epithelium
  • loss of parietal cells cause a rise in pH so loses it’s bacteriostatic effect and stops the conversion of pepsinogen
  • the tight junctions between cells are lost resulting in an influx of plasma proteins from the circulation into the gut lumen beginning the diarrhoea process
  • the destroyed glands form visible nodules as a result of epithelial hyperplasia

Clinical signs: anorexia, weight loss and profuse watery diarrhoea

2 Types of ostertagiosis:

  • Type 1 - seen in dairy replacement calves at the end of grazing, affects most calves in the group due to ingestion of large numbers of larvae due to shedding of animals the previous yea on pasture
  • type 2 - less common, seen in yearlings, causes acute disease with high mortality, due to emergence of hypobiosing L4 , clinical signs include thirst, anaemia and intermittent diarrhoea

treat clinically infected calves with ivermectin or moxidectin to target the larval stages

69
Q

What worms can be found in the abomasum?

A

HOT
Haemonchus contortus
Ostertagia ostertagi
trichostrongylus

70
Q

What worms can be found in the small intestine?

A

NAIROBI TRAVEL CENTRE
Nematodirus - adults resemble cotton wool
Trichostrongylus
Cooperia - most common, look like a coiled spring

71
Q

What worms can be found in the large intestine?

A

COT
chabertia - large buccal cavity

Oesophagostomum - big decorated head with a cephalic vessicle

Trichuris - long thin head with thickened tail

72
Q

What factors affect the epidemiology of ostertagia ostertagi

A
  • grazing system (inddor animals at much less risk, if pastures are rotated between young and old stock also has an effect)
  • climate - temp and rainfall (require warm moist climates and rainfall to aid distribution)
  • grass length
  • stocking density (increases pasture contamination)
  • Animals (young immune naive animals are more at risk )
73
Q

describe the general features of dictycaulus viviparous

A
  • causes parasitic bronchitis in cattle - common in dairy replacement heifers
  • significant pathogen in the UK
  • Slender white worms
  • males have a reduced bursa
  • adults found in trachea and bronchi
  • direct life cycles
74
Q

Describe the life cycle of Dictyocaulus viviparous

A
  • direct life cycles
  • females are ovo-viviparous which means they give birth to live larvated eggs
  • the larvated eggs hatch immediately in the lower respiratory tract
  • the L1 are coughed up and swallowed where they are then passed in faeces
  • the L1 are short and stumpy and look like refractive rice granules
  • L3 develops in the sheath from L1 and L2
  • L3 is the infective stage
  • L3 migrates to the lymph nodes where it moults to L4
  • L4 migrates to the lungs where it becomes trapped in capillaries where it burrows out into the alveloli (lympho-tracheal migration)
  • the L4 moult to L5 and then migrate up the bronchial tree to settle in the trachea and bronchi
  • about 55 ays after initial infection the immune system expels the adult worms resulting in protective immunity
75
Q

Describe the pathogenesis, diagnosis and treatment of dictyocaulus viviparous

A
  • intense inflammatory response caused by larvae in lungs resulting in alveolitis, bronchitis and bronchiolitis, interstitial emphysema, coughing, respiratory distress, tachypnoea, weight loss and pulmonary oedema
  • adults can cause an intense inflammatory response causing gasping, coughing, emphysema, hypoxia and frothy white mucous

some animals have lasting damage of epithelialisation of the lung tissue which can reduce productivity

Diagnosis via clinical signs, baermans test to detect L1 in faeces or an ELISA

Treatment - NSAIDs, antibiotics and rapid use of anthelmintics - is a prophylactic live attenuated vaccine

76
Q

Describe the epidemiology of dictyocaulus viviparous

A
  • very unpredictable, often seen in sporadic outbreaks
  • temperature, moisture dependent larvae
  • can use pilobolus fungi which grow in faecal pats for dispersal as the heads explode
  • L3 capable of overwintering
  • L1 can be shed by carrier animals
77
Q

Describe the general features of Babesia in Cattle

A
  • have an apical complex which aids attachment to host cells
  • intra-erythrocytic parasite
  • spread by the ixodes ricinus tick
  • babesia divergens is the main type in the UK
  • have 2 paired merozoites which sit within the RBC
  • 2 main types of babesia - small and large - the small are more pathogenic
  • has inverse age resistance so calves are immune to the disease up to 9 months of age but are still capable of being infected. These cattle who are affected young but don’t get the disease then become resistant to the parasite
78
Q

Describe the life cycle of Babesia

A
  • merozoites divide asexually in the RBC by binary fission
  • a tick is infected by ingesting an infected red blood cell
  • the merozoites then reproduce sexually within the tick and these disseminate through the tick tissues and penetrate the eggs of females
  • this results in the ticks being born infected by babesia - this is trans-ovarian transmission
  • the infected ticks then release babesia back into the cattle when they feed - sporogony occurs within the salivary glands and sporozoites are injected into the host
  • sporozoites invade the RBCs and begin to divide
79
Q

Describe the pathogenesis, diagnosis and treatment of babesia

A
  • clinical signs often known as red water fever - pyrexia, haemolytic anaemia, haemoglobinuria, diarrhoea
  • acute onset, high mortality
  • particularly affects yearlings
  • diagnosis based on history, clinical signs and a blood smear
  • treat with imidocarb - special license required to get it - sometimes animals also need a blood transfusion
80
Q

Describe the general features of cryptosporidium

A
  • parasitises mucosa, in particular the gut
  • intracellular parasite
  • found in the microvilli border of the enterocytes - enterocytoplasmis
  • not host specific
    sporulation occurs inside the hose
  • common cause of diarrhoea in young calves
  • faeco-oral transmission
  • very environmentally resistant oocysts shed into the environment
  • causes enteritis, villus atrophy, crypt hyperplasia and loss of mature epithelial cells
  • control involves practising good hygiene in particular check water sources and prevent bum to snout contact in calves
  • diagnosis via presence of oocysts in faeces using special staining
81
Q

Describe the life cycle of cryptosporidium

A
  • oocyst are ingested which results in activation and sporolates to release 4 sporozoites which bind to epithelial cells and infiltrate.
  • Once inside the cell the sporozoites go through a series of asexual reproduction to produce trophozoites then merozoites
  • the merozoites then undergo sexual reproduction to produce male and female counterparts which produce zygoes which then produce oocysts which are shed in faeces
82
Q

Describe the general characteristics of neospora caninum

A
  • apicomplexan protozoal parasite similar to toxoplasma gondii
  • affects cattle and dogs along with other mammals - deer are the natural intermediate host
  • in dogs it affects young puppies and preents as neurological symptoms such as ataxia and ascending paresis of the hindlimbs
  • in cattle it causes abortion and is common worldwide
  • no evidence of cow - cow transmission of zoonoses
83
Q

Describe the life cycle of neospora caninum

A
  • has a complex life cycle similar to toxoplasma gondii
  • Dogs scavenge infected bovine tissue and ingest bradyzoites arrested in the muscle
  • tachyzoites reproduce sexually in the gut of the dog to produce oocysts which are excreted in faeces
  • oocysts sporulate and an be eaten by the animals on the pasture
  • bradyzoites reside in cysts in the muscle and neurological tissue of cattle and other mammals

2 types of transmission in cattle:
- exogenous transplacental transmission - pregnant cows ingest oocysts which sporulate allowing sporyzoites to move around the body to form bradyzoite cysts. Tachyzoites cross the placenta to infect the foetus which results in abortion or a persistently infected calf - can sometimes see neurological defects or can be asymptomatic

  • Endogenous tansplacental transmission - resulting from a persistent infection, involving a persistently infected cow born to an infected mother having her own offspring which are infected due to the reactivation of bradyzoites to differentiate into tachyzoites and cross the placenta
84
Q

Describe the control and diagnosis of neospora caninum

A
  • diagnosis via maternal serology for antibodies using an ELISA - however can be unreliable as antibodies fluctuate during pregnancy
  • second trimester of pregnancy tests give more reliable results
  • can also test aborted foetus
  • control involves identifying positive cows and cull, embryo transfer and keep dogs away from cattle and prevent dogs scavenging to reduce the risk of infection
85
Q

Describe the general features of nematodirus spp

A
  • inhabits the small intestine of sheep - especially lambs, sheep develop immunity
  • adults are found in groups with the appearance of tangled cotton wool
  • females lay large eggs which can be seen in the uterus
  • have cephalic vesicles and males have long thin spicules
  • eggs of N.battus are oval with straight sides and a brown casing, the contents looks like round nodules
  • the eggs of N.fillicolis are oval shaped with rounded sides and a transparent casing
86
Q

Describe the life cycle of nematodirus spp

A
  • eggs are shed in faeces
  • L3 develops inside the egg then hatches and is ingested by animals
    L3 moults to L4 in the intestinal lumen where it then burrows into the mucosa and moults to L5 where it re-emerges
87
Q

Describe the pathogenesis, diagnosis and control of nematodirus spp.

A
  • developing L5 destroy the mucosa by making tracts where they’ve fed which an cause catharral enteritis where the GI lining has separated
  • only needs a low worm burden to cause disease
  • also result in villus atrophy which has an effect on absorption of nutrients
  • clinical signs include sudden bouts of acute watery diarrhoea, inappetance, abdominal pain, dehydration and thirst weight loss

Diagnosis involves history and clinical signs, time of year (May June seen most commonly), age of lambs

control via grazing management (resting fields previous year’s lambs were on), treat prophylactically with BZs
note resistance seen against MLs

88
Q

Describe the general features of telodorsagia circumcincta

A
  • Affect sheep, same morphology and life cycle as ostertagia ostertagi
  • causes the same pathogenesis as ostertagia but exacerbated by infection severity depending on nutritional status, development of an immune response and concurrent infection
  • results in parasitic gastroenteritis in the lambs in late summer - can also involve other gut parasites like cooperia and trichostrongylus
89
Q

Describe the general features of trichostrongylus species that inhabit the abomasum

A
  • Trichostrongylus axei - main one found in abomasum
  • not individually pathogenic usually contribute to parasitic gastroenteritis and can cause black scour
  • adults are small with an excretory notch
  • the L4 and L5 cause mucosal damage and villus atrophy leading to haemorrhage, oedema and diarrhoea due to them burying deep into and feeding on the mucosa
90
Q

Describe the general features of cooperia

A
  • component of parasitic gastroenteritis
  • adults are coiled like a spring with a cephalic vesicle
  • not as susceptible to anthelmintics and are therefore often the dose defining species
91
Q

Describe the general features of Haemochus contortus

A
  • lives in the abomasum of ruminants
  • adults are large with a cervical papilla, females have white ovaries wrapped around the gut (bbarbers pole)
  • typical strongyle life cycle - are capable of hypobiosis
  • L3 unable to survive on pasture over winter - ewe is the main source of pasture contamination
  • adults feed on blood and cause severe haemorrhagic gastritis
  • clinical signs include oedema, weight loss and anaemia
  • some evidence of resistance to Bzs
  • can diagnose with a faecal egg count
92
Q

Describe the general life cycle of tapeworm in sheep

A
  • adults live in small intestine
  • eggs laid into lower body compartments which break off and are called proglottids
  • eggs immediately infective once passed and are ingested by intermediate host
  • metacestode stage develops and these ar then eaten by the definitive host - usually a carnivore where the adult then develops in the small intestine
93
Q

What metacestodes can be found in sheep

A
  • Taenia Ovis - cysticercus cyst in muscles
  • Taenia Hydatigenia - cysticercus cysts in peritoneum
  • Taenia multiceps - coenurus in the brain
  • Echinococcus granulosus - hyadatid cysts
94
Q

Describe Taenia Ovis in sheep

A
  • sheep measles
  • forms cysticercus in the muscles
  • affects carcass value
  • a vaccine produced from a recombinant onchosphere has proven very effective against this
95
Q

Describe Taenia Hydatigena in sheep

A
  • cysticercus migrate through the liver of the sheep and for cysticerus cysts in the peritoneum
  • results in liver condemnation
96
Q

Describe Taenia Multiceps in sheep

A
  • forms cysts in the brain

- can result in neurological complications due to space occupying lesions

97
Q

Describe echinnococus granulosus in sheep

A
  • forms hyadatid cysts in the liver and lungs of sheep and cattle
  • considered a serious human pathogen
98
Q

Control of tapeworms

A
  • treat the dog with praziquantal which kills the adults and breaks the life cycle also avoid letting dogs scavenge and keep dogs away from grazing animals
99
Q

Which parasites pose a problem for outdoor pigs

A

hyostrongylus rubidus

metastrongylus apri

100
Q

Which parasites pose a problem for indoor pigs

A

ascaris suum
trichuris suis
oesophagostomum
strongyloides ransomi

101
Q

Describe the general features of Ascaris suum

A
  • very large worms
  • eggs have thick pitted shells and are very environmentally resistant
  • have typical ascarid life cycles
  • direct life cycles but earthworm acts as a paratenic host
102
Q

Describe the life cycle of Ascaris suum

A
  • eggs passed in faeces
  • larvae develop to L2 within the egg on the pasture
  • commonly eaten by earthworms
  • pigs ingest the L2 in the egg directly or via eating the infected worm
  • L2 undergo hepatotrahceal migration and become L3 in the lungs
    They are coughed up then swallowed where they develop into L4 and L5 in the small intestine
103
Q

Describe the pathogenesis, epidemiology and diagnosis of Ascaris suum

A
  • cause a hypersensitivity reaction due to migrating larvae
  • livers often condemned at abattoir due to milk spots
  • can cause transient pneumonia and adults in the small intestine can cause mechanical blockages and poor weight gain
  • diagnosis usually via abbatoir reports and can test for eggs in faeces but float in magnesium sulphate due to weight
    Immunity develops rapidly
  • note that sows can pass infection to piglets
104
Q

Describe the general features of strongyloides

A
  • most common species in pigs is strongyloides ransomi
  • affects younger animals
  • good immunity once infected
    adults are small, hair like worms and excrete eggs through genital pores
  • unique as can be parasitic or free living
  • capable of percutaneous infection
  • males are only present in free living lifestyles, the females are the only gender that is parasitic
  • females exist in the small intestine and breed asexually
  • infective L3
  • undergo hepatotracheal migration
  • L3 can become arrested in muscles of sows and are reactivated when pregnant to infect piglets via the ttransmammary route
105
Q

Describe the general features of trichuris

A
  • commonly known as the whip worm
  • inhabits the large intestine characteristic eggs - lemon shaped with 2 opperculum - highly environmentally resistant
  • infectious stage is egg containing L1
  • resistant to many anthelmintics
  • causes weight loss in pigs
106
Q

Describe the general features of oesophagostomum

A
  • strongyle nematode found in the large intestine of pigs and ruminants
  • adults around 2cm and have characteristic cephalic vesicles
  • have typical strongyle life cycles
  • L3 is the infective stage
  • L4 develop in the mucosa forming nodules
107
Q

Describe the general features of Hyostrongylus rubidus

A
  • trichostrongyle nematode found in the stomach of pigs, similar to ostertagia ostertagi
  • capable of hypobiosis
  • can cause gastritis
108
Q

Describe the general features of metastrongylus apri

A
  • lungworm of pigs
  • doesn’t behave like a typical metastrongyle
  • has an intermediate host - the earthworm
  • adults live in the lumen of the bronchi and bronchioles
  • disease typically seen in pigs ages 4-7 months
  • clinical signs include coughing, dyspnoea, nasal discharge and reduced weight and inappetence
  • can exacerbate other respiratory diseases
  • undergoes lymphotracheal migration
  • L3 in earthworm infective stage
109
Q

Name the burrowing mites of chickens

A

Knemidocoptes

110
Q

Name the non-burrowing mites of poultry

A

Dermanyssus gallinae

Ornithonysuss silvarium

111
Q

Name the lice of poultry

A

menacanthus

lipeurus

112
Q

Describe the general features of Knemidocoptes

A
  • burrowing mite with a similar appearance and life cycle to Sarcoptes scabei
  • can affect other avian species such as parrots and budgies
  • infects lightly feathered areas - often the face
  • form extensive crusting lesions

2 main types:

  • Knemidocoptes mutans - causes scaly leg
  • Knemidocoptes gallinae - causes a depluming itch

birds infected are incredibly uncomfortable and itchy

113
Q

Describe the general features of Dermanyssus gallinae

A
  • commonly known as the red poultry mite
  • non-burrowing blood feeder of both domestic and wild birds
  • major economic importance
    lives in the environment and attacks host at night
  • mites appear bright red when engorged with blood, then turn black
  • have a D shaped anal plate
  • can survive months in the environment allowing populations to rapidly build up
  • on the brird may see pruritis, papules and crusts
  • infected birds can become anaemic, stop feeding and become debilitated
  • acaricides to treat the environment are needed to exterminate
114
Q

Describe the general features of ornithonyssus

A
  • commonly known as the northern fowl mite
  • non-burrowing with a similar morphology to dermanyssus gallinae
  • permanent blood feeders can be identified on the host
  • infected birds show feather discolouration and anaemia
  • anal plate is pear shaped
115
Q

Descibe the general features of lice on poultry

A
  • all lice infecting poultry are chewing lice
  • 3 main species:
    1. liperus caponis - found on the underside of the wings and on tail feathers
    2. menacanthus stramineus - the body louse
    3. menopon gallinae - the shaft louse
  • affect all types of domestic fowl
  • feed on feathers and down
  • infected birds are irritated and unable to rest, body weight decreass and egg production drops
  • mainly seen in autumn and winter
116
Q

Describe the general features of Trichostrongylus tenuis

A
  • highly pathogenic
  • big problem in game birds
  • causes erosion of the mucosa
  • outbreaks seen to occur
  • same basic biology and morphology as other trichostrongylus species
117
Q

Describe the general features of syngamus trachea

A
  • commonly known as gape worm
  • hook worm infecting the trachea
  • has a wild bird reservoir
  • male and female are permanently paired forming a Y shape
  • direct life cycle
  • can cause mechanical blockage of the trachea resulting in coughing gasping and asphyxia
  • eggs passed in faeces - lemon shaped with an opperculum at both ends and visible blastomeres
  • several routes of infection:
    1. ingestion of egg containing infective L3
    2. ingestion of transport or paratenic host - usually earthworm
    3. ingestion of the free L3 larvae
  • L3 migrates to the lungs via the blood stream from the gut
118
Q

Describe the basic features of capillaria

A
  • some have direct, others have indirect life cycles
  • those with direct life cycles tend to infect birds in indoor systems while those with indirect life cycles tend to infect outdoor birds
  • very thin worms with an oesophagus which looks like a stack of polos
  • found in the crop, oesophagus or the small intestine depending on the species
  • characteristic barrel shaped eggs - thick shelled, 2 mucoid plugs, lemon shaped
  • infective L1 in the egg is eaten by the worm
  • can be highly pathogenic - head of worm buried deep in the mucosa causing inflammation resulting in inappetence, weight loss and decreased egg production
119
Q

Briefly describe the general features of poultry ascarids

A
  • common in chickens
  • small worm found in caecum - heterakis gallinarum
  • large worm found in small intestine - ascaridia galli
  • no migration occurs
  • eggs of different species are indistinguishable
  • infective stage is L2 in the egg
  • low pathogenicity but Heterakis gallinarum is a vector for a highly pathogenic protozoan species - histomonas meleagridis
120
Q

Describe the general features of Histomonas meleagridis

A
  • highly pathogenic
  • big problem in turkeys
  • causes severe necrotic entero-hepatitis
  • high mortality
  • amoeboid protozoan with a single flagellum
  • causes combs and wattles to turn a dark blueish purple due to cyanosis
  • trophozoites in the caecum erode the epithelium and invade the liver causing saucer like necrotic lesions
  • clinical signs include depression, ruffled feathers and sulphur yellow faeces
  • protozoa transmitted in the eggs of heterakis gallinarum
  • those who survive have lasting damage and never reach full productivity
  • chickens are asymptomatic carriers care housing them together or near each other with turkeys
121
Q

What is the only licensed poultry anthelmintic

A

flubendazole

122
Q

Briefly describe the general features of trichomonas gallinae

A
  • protozoa that affects finches, pigeons, birds of prey
  • causes oral canker and cheesy yellow material around the beak
  • direct transmission occurs
123
Q

Briefly describe the general features of hexamita meleagridis

A
  • protozoa that affects young game birds
  • results in bright yellow watery diarrhoea
  • no treatment
  • direct transmission
124
Q

Describe the general features of Eimeria

A
  • protozoa
  • species specific to a certain animal
  • more likely to affect young naive chickens
  • provides good immunity following infection
  • clinical signs include - diarrhoea, listlessness
  • PM can reveal parasite stages
  • transmitted via faeco-oral route
  • inhabit the intestinal tract
  • severity of the disease relates to parasite density
  • causes damage to intestinal epithelial cells impairing the absorptive capacity of the gut
125
Q

Describe the life cycle of Eimeria

A
  • unsporulatd oocyst deposited in faeces
  • sporulation occurs
  • sporulated oocyst ingested where it infiltrates epithelium in the gut and reproduces asexually to form schizonts
    The schizonts emerge from the sporozoite and then produce sexually to produce macro and microgametes which can reproduce sexually to produce the oocysts
126
Q

Describe the eggs of toxocara and toxascaris species

A
  • toxocara eggs are spherical with a dark cellular mass and a thick pitted shell
  • toxascaris eggs were more oval shaped with smoother shells and contents that doesn’t fill the egg

Veterinary Year 3 (12 decks)

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