Nematodes Flashcards
What is the usual infectious stage of a nematode?
L3
What is the basic lifecycle of a nematode?
- Reproduce sexually in DH
- Direct: hatch > 2 larval moults > L3 ingestion > infect host. Indirect: 2 moults in IH > final host infected by IH
What is the free living stage of a nematode?
L1-L3
Name the 3 dog and cat nematodes.
Toxocara canis (ascarid = roundworm)
Angiostrongylus vasorum (lung/heartworm)
Ancylostoma caninum (hookworm)
What is the type of lifecycle of toxocara canis?
Direct in dogs
Humans can be accidental hosts = zoonotic
What is the lifecycle of toxocara canis in puppies?
- Host ingests embryonated eggs
- Hatch
- L3 in intestine
- Hepatic tracheal migration
- L4 returns to intestine
- Adult
What are the clinical signs of toxocara canis in puppies?
Pneumonia
Pulmonary oedema
What is the lifecycle of toxocara canis in older dogs?
Larval encysts in tissues = hypobiosis = inactive
What is the lifecycle of toxocara canis in bitches?
- Encysts reactivate from tissue
- Infect puppies via transplacental and transmammary transmission
How is toxocara catis different in cats to dogs?
- No transplacental transmission
- Mainly transmammary so clinical signs GI
What are the hosts for angiostrongylus vasorum?
DH = dog
IH = slug/snail
What is the PPP of angiostrongylus vasorum?
7 weeks
Adults can live in dog for up to 2 years
Describe the lifecycle of angiostrongylus vasorum?
- Dog eats IH
- L3 penetrates intestine
- Migrate to abdominal lymph nodes to moult to L5
- Hepatic vein to right ventricle
- Become adults in pulmonary arteries
- Eggs carried into lung capillaries for embryonation
- L1 larvae coughed up
- Swallowed
- L1 excreted in faeces
- IH ingests
What are the clinical signs of angiostrongylus vasorum?
L1 in pulmonary arteries = vessel blockage = heart failure
Coughing blood
Anaemia
Tachycardia
What is the lifecycle of ancylostoma caninum?
- L3 penetrate skin
- Heart
- Lungs
- Moult to L4 in bronchi
- Some to muscles to reactivate in pregnancy and pass in milk.
- L4 swallowed to small intestine
- Moult to lay eggs
- Adult blood feeders
What are the clinical signs of ancylostoma caninum?
Anaemia
Respiratory signs
Skin lesions
Cutaneous larval migrans in humans
Name the 6 horse nematodes.
Strongylus species
Cyathostominae
Paracaris equorum
Oxyuris equi
Thelazia lacrymalis
Habronema microstoma
What is the strongylus lifecycle?
- Eggs
- L3 in faecal pat
- L3 ingested
- Penetrate mucosa
- Moult to L4
- Moult to immature adults
- Return to intestine
What is the lifecycle of stromgylus vulgaris?
- L4 penetrate submucosal arteries
- Migrate via the caecal and colic arteries
- Cranial mesenteric artery
What is the PPP of strongylus vulgaris?
6-7 months
What is the lifecycle of strongylus endentatus?
- L3 travel via portal system
- Moult to L4
- Migrate through liver
- Sub-peritoneum
What is the PPP of strongylus endentatus?
10-12 months
What is the lifecycle of strongylus equinus?
- L3 from nodules within intestine wall
- Travel across peritoneum
- Liver and pancreas
What is the PPP of strongylus equinus?
8-9 months
Describe the pathogenesis of strongylus vulgaris.
Most common strongylus leading to pathology. Endoarteritis (mesenteric) > thromboembolic infarction in large intestine. Adults cause blood loss and ulceration.
What are the clinical signs of strongylus vulgaris?
Weight loss
Anorexia
Anaemia
Diarrhoea
Fever
Colic
Death from intestine infarction
What do adult strongylus vulgaris look like?
Dark red 5cm large intestine
What is the location of strongylus equinus and endentatus?
Large intestine
What is the lifecycle of cyathostominae?
- Horse ingests L3
- Enter mucosa of large intestine
- Moult to L4
- Emerge into lumen to become adult
- Eggs pass out of faeces
- L3 migrate out onto grass
What is the PPP of cyathostominae?
6-8 weeks
Do cyathostominae undergo hypobiosis?
Yes. L3 can undergo hypobiosis in large intestine mucosa, winter = spring disease
How is cyathostominae diagnosed?
FEC, but this could be negative. ELISA
How is cyathostominae controlled?
Pasture poo picking
Targeted selective treatment with anthelmintics
What are the clinical signs of cyathostominae?
Weight loss
Colic
Larval cyathostominae = 50% death due to mass emergence of hypobiosis L3 in early spring
What is the appearance of cyathostominae?
Small redworms
What is the lifecycle of paracaris equorum?
- Eggs excreted on pasture
- L2 develops in egg, viable for years
- Eggs ingested
- L2 hatch in gut
- Migrate to liver
- Becomes L3 in liver
- Lungs via heart
- L3 migrate up trachea
- Coughed up and swallowed
- Adult in small intestine
What is the PPP of paracaris equorum?
12-16 weeks
What is caused by the migration of paracaris equorum?
Haemorrhage in liver and lungs, intestinal obstruction
What are the clinical signs of paracaris equorum?
Coughing
Nasal discharge
Weight loss
Colic
What is the method of transmission of strongylus vulgaris?
Eggs from faeces of infected horses hatch to L3 on pasture and are ingested
What are the methods to reduce infection pressure for strongylus vulgaris?
- Poo pick twice weekly
- Pasture rotation
- Co-grazing
- Regular FEC and larval culture
- Quarantine and treat new arrivals
What is the method of transmission of cyathostominae?
Eggs from faeces of infected horses hatch to L3 on pasture and are ingested
What are the methods to reduce the infection pressure of cyathostominae?
- Poo pick twice weekly
- Pasture rotation
- Co-grazing
- Regular FEC and cyathostomin ELISA
- Quarantine and treat new arrivals
What is the method of transmission of paracaris equorum?
Eggs from faeces of infected horses on pasture are ingested
What are the methods to reduce infection pressure of paracaris equorum?
- Poo pick twice weekly
- Avoid grazing youngstock on pastures in successive years (pasture rotation)
- Regular FEC
- Quarantine and treat new arrivals
What is the lifecycle of oxyuris equi?
- Adult in colon
- Migrate to anus to deposit eggs
- Eggs rubbed onto grass
- L3 develop in eggs
- Eggs ingested
- Hatch to L3 in colon where they moult to L5
What is the PPP of oxyuris equi?
5 months
What is caused by oxyuris equi?
Anal itching
FEC negative as eggs around anus not faeces
What is the lifecycle of thelazia lacrymalis?
- Adults in conjunctiva
- Muscid fly IH ingested L1
- L3 emerge
- Fly feeds on tears to infect
- 1 month to become adult
What disease is caused by thelazia lacrymalis?
Conjunctivitis
What is the lifecycle of habronema microstoma?
- Adults in stomach
- Eggs in faces hatch to L1
- Ingested by fly maggots
- L3
- Adult flies feed on tears and wounds
- L3 burrow into skin
- Develop into adults
Name the 3 pig nematodes.
Ascaris suum
Trichuris suis
Trichonella spiralis
What is the lifecycle of ascaris suum?
- Excreted in faeces
- Infective stage is egg containing L2
- Worm/bettle ingests
- L2 encysts
- Pig ingests eggs or worm/beetle
- L2 burrow into intestinal wall
- Enter hepatic portal system
- Liver
- Become L3
- Migrate in blood to lungs via veins
- 4-6 days later L3 migrate up bronchial tree
- Pharynx
- Swallowed
- L3 moults to adult in small intestine
What is the PPP of ascaris suum?
6-8 weeks
What is the pathogenesis of ascaris suum?
Migrating larvae = milk spot fever = condemnation of liver at slaughter
What are the clinical signs of ascaris suum?
Pneumonia
Predispose to infections
Affect growth rates
Describe the epidemiology of ascaris suum.
- Eggs survive years in environment
- Piglets infected early birth and immunity as adults
- Seasonal occurrence is higher in summer
How is ascaris suum diagnosed?
FEC but pigs are coprophagic so may have low egg counts. Observe worms in faeces
What is the appearance of ascaris suum?
Thick (typical ascarid)
What is the lifecycle of trichuris suis?
- Eggs excreted in faeces
- L1 develop in eggs
- Eggs ingested
- Hatch in intestine
- L1 penetrate caecum and colon
- Moult to L5
- Some adults emerge, most remain embedded in mucosal layers
What is the PPP of trichuris suis?
7-10 weeks
What is caused by trichuris suis?
Low pathogenicity but severe causes diarrhoea, anaemia and anorexia
What is the lifecycle of trichinella spiralis?
Indirect - no free living stage.
- Larvae in muscle of DH/pig
- Adult in small intestine
- L1 travel via blood to muscles and encyst
- Must be eaten to become an adult
Is trichinella spiralis zoonotic?
Yes. Humans infected by eating muscle with encysted larvae
How do domestic pigs become infected with trichinella spiralis?
Eating undercooked food waste, rodents IH and each other’s tails
What is caused by trichinella spiralis?
Young pigs = diarrhoea, inappetence, weakness
Human = diarrhoea, fever, muscle pain
How is trichinella spiralis controlled?
- Boil waste before feeding to pigs
- Meat inspection
- Eliminate rodents
- Freeze/cook meat to kill L1
Name the 3 cattle nematodes.
Ostertagia ostertagi
Cooperia oncophora
Dictyocaulus viviparus (lungworm)
What is the lifecycle of ostertagia ostertagi?
- Eggs passed in faeces
- Hatch to moult to L1-L3
- Migrates on pasture
- L3 ingested by host
- L3 exsheath in rumen
- Develop to L4 in gastric gland of abomasum
- Adult
- Females lay eggs in lumen
What is PPP of ostertagia ostertagi?
21 days
Does ostertagia ostertagi undergo hypobiosis?
Yes, up to 6 months
How is ostertagia ostertagi identified?
FEC - thin shells
Adults - male has bursa, female vulva
Describe the pathology of ostertagia ostertagi?
- Develop in gastric gland = reduced mass
- pH increases = loss of bacteriostatic effect in abomasum
- Enhanced permeability = increased proteins = expense of muscle and fat
- Hyperplasia in mucosa
What are the clinical signs of ostertagia ostertagi?
Diarrhoea
Dehydration
Anorexia
Death
High plasma pepsinogen
Death
Describe the epidemiology of type 2 ostertagia ostertagi?
- Calves in 1st grazing season
- July onwards risk of disease
- High morbidity, low mortality
- Diarrhoea, poor weight gain
- High FEC
- Pasture rest = most L3 die
Describe the epidemiology of type II ostertagia ostertagi.
- Yearlings
- Maturation of larvae from hypobiosis - L4 arrest (ingested previous autumn)
- Disease late winter/early spring
- Low morbidity, high mortality
- Diarrhoea, anaemia
- Low FEC
How is ostertagia ostertagi diagnosed?
FEC
ELISA
What is the lifecycle of cooperia oncophora?
- Egg hatch in faeces
- L1-L3
- L3 migrate out of faeces onto pasture
- INgested by host
- L3 exsheath in rumen
- Moult to L4
- Moult to adult on small intestine mucosa
- Female lays eggs that pass out faeces
What is the PPP of cooperia oncophora?
14-21 days
How is cooperia oncophora identified?
FEC and culture to L3 to confirm species
Describe the epidemiology of cooperia oncophora.
Overwintering by hypobiosis
What are the clinical signs of cooperia oncophora?
Adults: carriers, few signs of infection
Heavy burden: weight loss, inappetence, diarrhoea
What is the lifecycle of dictyocaulus viviparus?
- Adult in lungs
- Eggs in trachea
- Coughed up
- Swallowed
- Hatch to L1 in GIT
- L1-L3 in faeces (L3 overwinter)
- L3 move through fluid via pilobolus fungi to grass
- Ingested
- L3 via intestine to lymph nodes to be L4
- Carried via blood to lungs
What is the PPP of dictyocaulus viviparus?
25 days
What are the clinical signs of dictyocaulus viviparus?
Severe bronchitis
Pneumonia
Coughing
Death - worse in very young
How is dictyocaulus viviparus identified and diagnosed?
L1 in fresh faeces or sputum
ELISA
Describe the pre-patent, patent, post-patent and re-infection phases of dictyocaulus viviparus pathogenesis.
Pre-patent: larvae in alveoli and bronchi = alveolitis/bronchitis
Patent: frothy mucus, parasitic pneumonia caused by egg and L1 aspiration = collapsed bronchi
Post-patent: if calf recovers, months to heal = fatal flares/fibrosis, dead worm material infection
Re-infection husk: immune animals exposed to L3 challenge = lymphoid in bronchi, coughing (not death)
Describe the epidemiology of dictyocaulus viviparus.
- Common in calf first grazing then immunity develops
- Older animals infected if no prior exposure
- Overwintered larvae and carrier animals
- Disease July to September
How is dictyocaulus viviparus controlled?
Lungworm vaccine prevents disease but pasture still has contamination so low levels of infection still occur.
Anthelmintics do not allow immunity.
What fungi is able to disperse the larvae of dictyocaulus viviparus?
Pilobolus fungi on faecal pat
Name the 3 sheep nematodes.
Teladorsagia circumcinta
Nematodirus battus
Haemonchus contortus
What is the lifecycle of teladorsagia circumcinta?
Direct.
1. Eggs out faeces
2. Moult L1-L3
3. L3 exsheath in rumen
4. Enter gastric glands of abomasum
5. Moult to L5
6. Emerge from glands
7. Become adult in lumen
What is the PPP of teladorsagia circumcinta?
16-21 days
Does teladorsagia circumcinta undergo hypobiosis?
Yes. L3 may in gastric glands up to 6 months
How is teladorsagia circumcinta identified?
Eggs in faeces
Worms PM
Red/brown worms
Bursa in male
Buccal cavity
What is the pathology of teladorsagia circumcinta?
Developing larvae in gastric gland = distention, thick hyperplasia of mucosa
What are the clinical signs of teladorsagia circumcinta?
Anorexia
Diarrhoea
Dehydration
Weight loss
Death
High plasma pepsinogen
Describe the epidemiology of type I teladorsagia circumcinta.
- Lambs with no immunity
- Depends on climate, increase during lambing
- Periparturient egg rise PPR
- L3 infective
- Disease July-November
Describe the epidemiology of type II teladorsagia circumcinta.
- Animals infected late autumn = L3 may hypobiose and overwinter within host
- Disease as emerge following spring
- Slow immunity, 2 grazing seasons
How is teladorsagia circumcinta controlled?
Anthelmintic
Stock management in rotation grazing
What is the lifecycle of nematodirus battus?
- Eggs passed in faeces
- L1-L3 in egg
- L3 hatch due to climatic stimulus cold less than 10 degrees C
- L3 exsheath in rumen
- Moult to L4 in small intestinal mucosa
- L5 adult in lumen
What is the PPP of nematodirus battus?
14 days
How is nematodirus battus identified?
Brown eggs
Disease occurs during PPP so FEC is not useful
What is the pathology of nematodirus battus?
Small intestinal damage
Enteritis
Malabsorption
What are the clinical signs of nematodirus battus?
Diarrhoea during PPP
Dehydration
Death, high mortality if untreated
What is the epidemiology of nematodirus battus?
- Eggs survive up to 2 years
- Overwintered eggs hatch the same time at temperatures less than 10 degrees C so large numbers of L3 suddenly in spring
- Immunity in adults
- Lamb-lamb transmission, spring flush
- Mass hatching in April
How is nematodirus battus controlled?
Avoid successive grazing of lambs on the same pasture.
Anthelmintic prophylaxis vs lamb lamb
What is the lifecycle of haemonchus contortus?
Direct
1. Eggs in faeces
2. L1-L3
3. Migrate to pasture
4. Ingested
5. L3 exsheath in rumen
6. Moult to L4 in abomasum
7. Feeds om blood in abomasum
What is the PPP of haemonchus contortus?
16-21 days
Does haemonchus contortus undergo hypobiosis?
Yes, up to 6 months
How is haemonchus contortus identified?
Adults in abomasum
Bursa in male
FEC
What are the clinical signs of haemonchus contortus?
Blood loss
Anaemia
Describe the pathology of haemonchus contortus?
Acute: haemorrhage, sudden death
Subacute: anaemia oedema
Chronic: weight loss, weakness
Describe the epidemiology of haemonchus contortus.
- High biotic potential
- Sudden appearance of disease
- Rapid development in warm, humid condition
- Spring-autumn
How is haemonchus contortus controlled?
Treat and move
Anthelmintics