Pigs

Question 1

What is the superfamily of ascaris suum?

Answer 1

Ascaridoidea

Question 2

What is the life cycle of ascaris suum?

Answer 2

Eggs excreted in faeces.
Earthworms/dung beetles ingest ascarid eggs whilst feeding on the soil.
L2 encysts in the tissue of the paratenic host.
Pigs are infected by ingesting eggs or an infected paratenic host.
L2 burrows into the intestinal wall, enters the hepatic portal system and travels to the liver. L2-L3.
L3 migrates in the bloodstream to the lungs via venous system.
4-6 days after infection, L3 migrates up the bronchial tree to the pharynx and are swallowed.
L3 moults to adults in the small intestine.

Question 3

What is the infective stage of ascaris suum?

Answer 3

Egg containing L2.

Question 4

What is the pre-patent period of ascaris suum?

Answer 4

6-8 weeks.

Question 5

What is the size of the male and female worms of ascaris suum?

Answer 5

Male: 15-25cm
Female: <40cm

Question 6

What is the pathogenesis of ascaris suum?

Answer 6

Liver migrating larvae causes milk spot. So the liver is condemned at slaughter.
Adult worms can cause obstruction in large numbers and a poor feed conversion.

Question 7

What are the clinical signs of ascaris suum?

Answer 7

Transient pneumonia in young. So can exacerbate other causes of pneumonia.
Heavy infections can predispose to bacterial/viral infections.
Significant impact on growth rates.
Life threatening in heavy infections.

Question 8

What is the epidemiology of ascaris suum?

Answer 8

Females are prolific and eggs can survive for years in the environment.

Piglets are infected early birth.

Highest prevalence: 3-6 months.

Immunity in adults.

Seasonal occurrence in temperature regions - higher in summer.

Question 9

How can ascaris suum be diagnosed?

Answer 9

Faecal egg count.
Observation of large worms in the faeces.
Post-mortem: milk spots and adult worms in the intestine.

Question 10

Why might pigs have a low egg count in their faeces?

Answer 10

They are coprophagic - eat their own poo.

Question 11

How can ascaris suum be controlled?

Answer 11

Treatment for secondary bacterial invaders, which are necessary during the respiratory phase of infection.
Anthelmintics.
Hygiene to prevent egg spread contamination.

Question 12

What is the superfamily of trichuris suis?

Answer 12

Trichuroidea

Question 13

What is the life cycle of trichuris suis?

Answer 13

Eggs are excreted in faeces. L1 develops in the egg.
Eggs are ingested and hatch in the intestine.
L1 penetrates mucosa in ileum, caecum, colon and moults to L5.
1/3 of adults emerge.
2/3 remain embedded in the mucosal layers.

Question 14

What is the pre-patent period of trichuris suis?

Answer 14

7-10 weeks

Question 15

What are the clinical signs of trichuris suis?

Answer 15

Severe cases:
Diarrhoea
Anaemia
Anorexia

Question 16

What is the super family of trichinella spiralis?

Answer 16

trichinelloidea

Question 17

What is the life cycle of trichinella spiralis?

Answer 17

No free living stage.

Adults in SI, L1 travels via blood to muscles where they encyst.
Host is consumed, then the L1 develops to adults.
The adults in the IH will produce L1, which encysts in the muscle of the IH.

Question 18

How can domestic pigs be infected with trichinella spiralis?

Answer 18

Eating uncooked food waste, rodents and other tails.

Question 19

How can humans be infected with trichinella spiralis?

Answer 19

Eating muscle with encysted larvae

Question 20

What is the pathogenesis of trichinella spiralis in young pigs and humans?

Answer 20

Young pigs: diarrhoea, inappetence and weakness.

Humans: diarrhoea, fever, muscle pain, dyspnoea.

Question 21

How can trichinella spiralis be diagnosed?

Answer 21

Digestion of small portions of the diaphragm muscle in pepsin/HCl.

Examination of sediment for L1.

ELISA for mass screening at slaughter houses.

Question 22

How can trichinella spiralis be controlled?

Answer 22

Boil food waste before feeding to pigs.
Meat inspection.
Eliminate rodents.
Freezing/cooking of meat to kill L1.