58. Porcine epidemic diarrhoea, haemagglutinating encephalomyelitis of pigs.

Question 1

PEDV History OCCURRENCE?

Answer 1

PEDV: Porcine epidemic diarrhoea,

History

• 1971 England Type I (InDel)

‣ Feeders and fatteners

‣ No clinical signs in suckling piglets

• 1976 Woods Type II (non-InDel)

‣ At all ages, piglets too

• Europe, South-East Asia
• Only pigs susceptible, usually less severe
• After outbreak, the virus may either disappear or persist, it can become an endemic
• After 2010, outbreaks in America and Asia
• 2013 USA: similar symptoms, 2 types of pathogenicity
• Mild diarrhoea in Europe

Question 2

Pathogenesis, clinical signs and diagnosis of porcine epidemic diarrhoea?

Answer 2

Pathogenesis (similar to TGE)

1. Viral intake: oronasal route
2. Virus replication: epithelial cells of lungs or large intestine, occasional replication in crypts
3. Viraemia
4. It can get into milk but not foetus
5. Virus shedding for 2 weeks
6. Cause of death ➝ dehydration, metabolic acidosis, hyperkalaemia consequence of heart failure

Clinical signs

• Profuse diarrhoea (depends on variant), vomiting
• Stomach ache in older animals
• After survival, the herd can be infection free or persistent carrier

Diagnosis

• Clinical signs
• IF, ELISA, Western blot, RT-PCR
• Isolation with trypsin on Vero cells (other cells can be good too)
• Replication in cells of bats ➝ change of host species

Question 3

Prevention of Porcine epidemic diarrhoea?

Answer 3

Prevention

• If survive Æ Passive immunization
• Vaccine: Inactivated, Recombinant (under development), DNA (under development), Attenuated
• (not used), Cross protection

Question 4

Haemagglutinating encephalomyelitis coronavirus (PHEV) History and ethiology?

Answer 4

Haemagglutinating Encephalomyelitis (PHEV)

Nomenclature

• Porcine haemagglutinating encephalomyelitis
• Ontario disease
• Vomiting-wasting disease

History

• 1962 Canada, Ontario
• 1969 England, Europe
• 1978 Australia
• Widespread, but clinical signs are rare, because they’re only seen in young piglets, but are protected by maternal

immunity ➝ appears sporadically

Etiology

• Betacoronavirus
• Unified antigen structure
• No cross-reaction
• CP
• HE proteins
• Natural host: swine
• Artificial: rate and mouse can be diseased

Question 5

Pathogenesis of Hpev?

Answer 5

Pathogenesis

1. Viral intake: oronasal route
2. Virus replication: asymptomatic replication in the respiratory tract, epithelial cells in the intestines (jejunum)
3. Into CNS via peripheral nerves ➝ vomiting: sensor ganglion of N. Vagus
4. Virus shedding until 8-10 days with nasal discharge, Antibody after 6-7 days, viraemia rare

Question 6

Clinical signs?

Answer 6

Clinical signs

- V/W: few days after birth

‣ Loss of appetite, enervation

‣ Vomiting: yellow-green

‣ Constipation, fever for 2-3 days

‣ Hairy pigs (death between 1-2 weeks)

‣ Piglets unable to suck or swallow or throw up shortly after suckling

‣ Weight loss, dehydration

‣ Rarely 4-6 weeks old ➝ loss of appetite, enervation, vomiting, weakness, paralysis

• Ontario disease: under 3 weeks

‣ Incubation: 4-7 days

‣ Shaking, arched back

‣ Bloated abdomen, unable to suck, loss of appetite, enervation

‣ Convulsions, rolling of eyes, trismus, pharyngeal paralysis

‣ Partial paralysis of limbs

‣ Cyanosis in end of legs

‣ Can recover without any remaining clinical signs

Question 7

Pathology of HPEV?

Answer 7

Pathology

• Piglets ➝ weight loss, dehydration, chronic cases: enlarged stomach
• Histology: non-purulent inflammation of grey matter of brain and spinal cord, mainly in brain stem and first part of

spinal cord, in dorsal horns (ventral horns in Teschovirus infection)

Question 8

Diagnosis, DD and prevention of HPEV?

Answer 8

Diagnosis

• Direct virus detection: brain, lung, tonsils
• Virus isolation: porcine kidney
• IF, VN, HAI, RT-PCR

Differential diagnosis:

1. Teschen-disease,
2. Talfan-disease,
3. Aujeszky disease

Prevention:

• Surviving of sows: colostral immunity -> susceptible piglets do not get sick

Question 9

Swine Acute Diarrhoea Syndrome Coronavirus (SADS-CoV)?

Answer 9

Swine Acute Diarrhoea Syndrome Coronavirus (SADS-CoV)

• SADS-CoV or PEAV (porcine enteric alphacoronavirus)
• From bats: 90 years ago
• China 2017
• Severe diarrhoea (experimental)
• Young age: 5 day old
• Mortality: 35-90%
• Environmental is similar to SARS
• SARS infected bats can have similar viruses like SADS-CoV

Question 10

Porcine Deltacoronaviruse (PDCoV)?

Answer 10

Porcine Deltacoronaviruse (PDCoV)

• Pigs with diarrhoea in USA 2014
• Mixed with PEDV 10%
• Bird origin
• Mortality: 30-40%
• Occurrence: USA, Canada, Mexico, Asia
• Pathogenesis, clinical signs, pathology ➝ similar to PEDV
• Diagnosis: IF, RT-PCR, Atg-detecting ELISA
• Vaccine development in USA