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Y3 Parasitology S2 > Pig Parasites of public health importance > Flashcards

Pig Parasites of public health importance Flashcards

1
Q

Name 3 zoonotic parasites of pigs

A
  • Trichinella spiralis
  • Taenia solium
  • Balantidium coli
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2
Q

Name the protozoal parasite of pigs

A

Cystoisospora suis

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3
Q

Name a mite of pigs

A

Sarcoptes scabei

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4
Q

Name a louse of pigs

A

Haematopinus suis

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5
Q

Describe the two groups of Trichinella spp

A
  • Encapsulated/encysted

- Non-encapsulated/do not encyst

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6
Q

Which spp of Trichinella is the main aetiological agent of Trichinosis?

A

Trichinella spiralis

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7
Q

Which spp are hosts of Trichinella?

A

Wide range of hosts

  • All types of animals but amphibians
  • Pigs, horses, humans
  • Carnivores!
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8
Q

Describe the worldwide distribution of Trichinella

A

Everywhere but Antarctica

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9
Q

Describe the features of Trichinella spiralis and its life cycle

A

Intracellular nematode
No eggs or larvae in faeces
No free living stages

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10
Q

Describe the females/eggs of Trichinella

A

Females are larviparous

L1 – Newborn larvae (NBL)

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11
Q

Which stage of Trichinella is infective?

A

L1 muscle larvae

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12
Q

How do animals become infected with Trichinella?

A

Ingesting contaminated meat that contains the L1 muscle larvae

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13
Q

Where does L1 - L5 development of trichinella occur?

A

In the small intestine

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14
Q

Describe what happens to the L1 larvae of Trichinella after they are ‘born’ including how they become infective

A

NBL (L1) born, migrate in blood and lymphatic system to skeletal muscle, invade a single muscle cell = muscle larvae (ML)
Parasite forces a terminally differentiated muscle cell to go back into the cell cycle so the parasite can grow – deposition of collagen around itself to create the cyst – the parasite stays as an L1 throughout this process

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15
Q

What is a nurse cell?

A

Muscle cells infected by a single muscle larvae

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16
Q

Which spp are affected by Trichinella disease?

A

No disease in domestic animals but can cause serious disease in humans

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17
Q

How does infection of trichinella occur?

A 
Infection occurs by the consumption of raw or undercooked contaminated meat
Main sources of infection:
- Pigs and horses
- Game meat
- Arctic animals
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18
Q

What are the clinical signs of Trichinella?

A

Typical trichinosis symptoms: abdominal pain, diarrhoea, fever, chills and peri-orbital oedema
Severe cases – myocarditis, encephalitis, secondary infections (pneumonia) and even death

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19
Q

How is Trichinella diagnosed?

A
  • Microscopic examination of biopsy samples

- Identification of larvae digested from muscle tissue using HCl-pepsin

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20
Q

How is Trichinella treated?

A
  • Albendazole/mebendazole
  • Early diagnosis and prompt treatment can kill adults and prevent release of NBL
  • Once larvae established in muscle cells treatment may not eliminate infection and associated symptoms
21
Q

How is Trichinella controlled?

A
  • All breeding pigs (sows and boars) and pigs from non-controlled housing must be tested at slaughter for Trichinella
  • Wildlife are important reservoirs – monitoring using indicator animals (foxes and racoons)
  • Cooking at least 70 degrees (and freezing) meat will kill Trichinella parasites in most cases
22
Q

Name the pork tapeworm

A

Taenia solium - not in the UK

23
Q

What are the two routes of infection in people for Taenia solium?

A
  • Ingesting cysts in undercooked pork

- Ingesting eggs

24
Q

What are the symptoms of Taenia solium when cysts have been ingested?
How long after ingestion do signs develop?

A

Abdominal pain, nausea, diarrhoea or constipation may arise - ~ 8 weeks after ingestion of meat containing cysticerci

25
Q

What are the symptoms of Taenia solium when ingestion of eggs & development of metacestode stage have occured?

A

Cysts in muscle – generally no symptoms

Cysts in central nervous system – neurocysticercosis

26
Q

Describe the signs of neurocysticercosis

A
  • Focal epilepsy, epileptic seizures, hydrocephalus, chronic headaches, focal deficits and symptoms associated with increased intracranial hypertension
  • T. solium is the cause of 30% of epilepsy cases in endemic areas
27
Q

Why is Taenia solium not seen in the UK?

A

Due to good sanitation and meat inspection

28
Q

Name the ciliated protozoa found in the large intestine of pigs

A

Balantidium coli

29
Q

Describe the features of Balantidium coli and its disease

A
  • Important zoonosis, cause of intestinal disease in humans: pigs main animal reservoir
  • Faeco-oral transmission
  • Cyst and trophozoite stage
30
Q

Describe the life cycle of Balantidium coli

A

Cyst is ingested and within the SI the parasite encysts, becomes a trophozoite and then multiplies by binary fission
A proportion of the trophozoites will then encyst and then become the cyst stage which is passed out in the faeces to continue the life cycle

31
Q

Name the parasite that causes coccidiosis in pigs

A

Cystoisospora suis

32
Q

In what conditions does Cystoisospora suis occur?

A
  • Both indoor and outdoor production systems
  • In summer: sows with heavily contaminated udders from wallowing
  • Wet weather: beds not renewed between batches.
33
Q

Describe the disease and its presenting signs caused by Cystoisospora suis

A
  • Most common cause of scour in piglets 10-20 days old
  • Scouring seen in all or part of litter – yellow/cream looking, with possible blood flecks
  • Presents as diarrhoea that is unresponsive to antibiotics
  • Reduced weaning weights & possible secondary post-weaning enteritis
34
Q

Describe the life cycle of Cystoisospora suis

A

Infection – ingestion of sporulated oocysts (20µM – smaller than in dog and cat spp)
Small intestine - 2 rounds of asexual reproduction
Sexual reproduction – micro and macro-gametocytes that produce zygote = oocyst.
Self limiting

35
Q

What is the PPP of Cystoisospora suis

A

5days

36
Q

How is Cystoisospora suis diagnosed?

A

Clinical signs – strong indication of coccidiosis

Often low or negative oocyst counts – not definitive

37
Q

How is Cystoisospora suis treated?

A
  • Sulphonamides at 3, 10 and 17 days old

- Toltrazuril – one dose, preferably at 4-5 days old

38
Q

What are the considerations when treating Cystoisospora suis with Toltrazuril?

A
  • Early before gut damage: prevent clinical disease
  • Late infection: destruction of C. suis triggers an immune response protecting from future infections
  • 77 day meat withdrawal period: recorded in medicines records.
39
Q

How is Cystoisospora suis controlled?

A

Indoor - removing contaminating oocysts from environment, resistant to most conventional disinfectants but lime washing effective.
Outdoor - arcs must be moved between consecutive farrowings and boards should be avoided

40
Q

Describe the features of Sarcoptes scabei

A
  • Burrowing mite, spends entire life cycle on the host
  • Lays eggs in tunnels within the skin
  • Life cycle (all stages within epidermis): 10-15 days
41
Q

What are the clinical signs of a Sarcoptes scabei infection

A
  • Lesions commonly start around the ears, spread to back, flanks and abdomen
  • Severe immune reaction, pruritis and erythema.
  • Intense itching, thickened skin, head shaking, secondary bacterial infections
42
Q

How is Sarcoptes scabei transmitted?

A

direct contact - sow to piglet

43
Q

How is Sarcoptes scabei treated/prevented?

A

Treat/prevent with MLs – in feed or injectable (depending on time of slaughter)
Cleaning/disinfecting wooden and concrete surfaces

44
Q

Describe the features of Haematopinus suis

A
  • Sucking louse
  • Only louse found on pigs: common, present at low levels
  • Nymphal lice - around the ears and skin folds of upper legs
  • It’s really large!! (5-6mm)
  • Egg to adult form – ~4 weeks
45
Q

What are the signs of Haematopinus suis

A
  • Itching, reduces feeding and growth rates and also affects hide value
  • Blood sucking parasite: anaemia in piglets, viral infections (PRRS, PCV2 & Swine pox) from pig to pig
46
Q

Name two parasites of pigs that are zoonotic and that could be detected at slaughter

A

Trichinella spiralis and Taenia solium

47
Q

Why is the life cycle of Trichinella spiralis unusual for a nematode parasite?

A

Intracellular parasite. No free-living stages and no eggs/larvae passed in faeces. Transmission by ingestion of L1 in muscle – carnivorous life cycle. Female worms are larviparous.

48
Q

How do pigs become infected with Taenia solium?

A

Ingestion of embryonated eggs or gravid proglottids released into the environment in human faeces.

49
Q

How might you detect and control an outbreak of Sarcoptes spp. in a group of indoor pigs?

A

Diagnosis based on clinical signs of acute pruritis, thickened skin, head shaking and secondary bacterial infections and deep skin scrapes to find the mites. Treat with injectable/ in feed ivermectin. Ensure housing is cleaned effectively to remove contamination.

Y3 Parasitology S2 (13 decks)

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