13. Viral diseases of pig digestive system & diseases manifested on digestive system in respective pig categories

(Viral gastroenteritis, Epizootic viral diarrhoea, Coronavirus encephalomyocarditis in piglets = Rotavirus gastroenteritis, Syndrome of multisystemic wasting post weaning – PMWS, Adenovirus, Enterovirus infections – SMEDI syndrome & other enterovirus diseases, Foot & mouth disease, BVD & BD, Vesicular syndrome, congenital pox infection).

What are examples of viral diseases affecting the digestive system in swine?

1. Transmissible gastroenteritis (TGE)

2. Enzootic viral diarrhoea

3. Coronavirus encephalomyelitis

4. Rotavirus infection

5. Post-weaning multisystemic wasting syndrome

6. Adenovirus

7. Enterovirus

8. Bovine viral diarrhoea (BVD)

9. Border disease (BD)

10. Vesicular syndrome

What is transmissible gastroenteritis (TGE) in swine?

A common viral disease of the small intestine caused by the transmissible gastroenteritis virus, an RNA coronavirus, leading to vomiting and profuse diarrhoea in pigs of all ages

What is the primary cause of transmissible gastroenteritis in swine?

Transmissible gastroenteritis virus → Coronavirus

Which body systems do coronaviruses primarily affect?

1. Upper respiratory tract

2. Gastrointestinal tract

How is TGE transmitted?

Orofaecal route

What is the pathogenesis of TGE?

Infects & destroys villous epithelial cells of the jejunum & ileum, which results in severe villous atrophy, malabsorption, osmotic diarrhoea, & dehydration

What are the initial clinical signs of transmissible gastroenteritis (TGE) in nonimmune herds?

Vomiting followed by profuse watery/haemorrhagic diarrhoea, dehydration, and excessive thirst. Faeces of nursing piglets often contain curds of undigested milk.

What is the mortality rate for piglets under 1 week old affected by transmissible gastroenteritis (TGE)?

Nearly 100%

What is the treatment for TGE?

None. Supportive: fluids, electrolytes

What type of immunity is important for the prevention of transmissible gastroenteritis (TGE) in swine?

Lactogenic immunity

What is the primary prevention method for transmissible gastroenteritis (TGE) in swine?

Isolate sows, planned exposure for immunity, ensure new stock is free from infection, all-in all-out system, vaccination, hygiene, and biosecurity

What is epizootic viral diarrhoea (EVD) in swine?

Porcine Epizootic Diarrhoea (PED) (coronavirus, RNA) or Epizootic Viral Diarrhoea (EVD) (any viruses), associated with a high mortality rate in young piglets

What are the clinical signs of type 1 epizootic viral diarrhoea (EVD) in swine?

Profuse, watery diarrhoea in pigs under 5 weeks old

What are the clinical signs of type 2 epizootic viral diarrhoea (EVD) in swine?

Diarrhoea, decreased growth rate, dehydration, vomiting, and depression in pigs of all ages

What virus causes coronavirus encephalomyelitis in pigs?

Porcine hemagglutinating encephalomyelitis virus (PHEV)→ Betacoronavirus

What is the typical age group affected by coronavirus encephalomyelitis in pigs?

Pigs under 4 weeks old

What is the pathogenesis of coronavirus encephalomyelitis?

Transmitted virus replicates in the nasal epithelial mucosa, tonsils, lungs & small intestine & spreads via the peripheral nervous system to the CNS

What are the clinical signs of coronavirus encephalomyelitis in pigs?

Vomiting and Wasting Syndrome: Vomiting, wasting, sneezing, coughing, rapid dehydration, bruxism, pharyngeal paralysis, dyspnoea, cyanosis, coma, and death

Encephalomyelitis syndrome: Initial signs are similar to those above. Later, a variety of CNS signs

What is the treatment for coronavirus encephalomyelitis in pigs?

No treatment, euthanasia; prevention involves injecting piglets with hyper-immune serum at birth or lactogenic immunity from immune sows

What is rotavirus infection in swine?

A common diarrhoeal disease caused by double-stranded RNA viruses in the family Reoviridae affecting the small intestine of pigs

How is rotavirus infection in pigs transmitted?

Fecal-oral route

What is the pathogenesis of rotavirus infections?

Rotavirus destroys the enterocytes on the tip of the villi in the SI → malabsorption → lactase becomes deficient → lactose passing into the large intestine induces an osmotic diarrhoea. If neonatal pigs do not receive protective levels of maternal antibodies, they are likely to develop profuse watery diarrhoea in 12-48 hr.

Diarrhea often begins in pigs 5 days to 3 weeks old, or immediately after weaning, & lasts for 2-5 days.

Concurrent infection by enterotoxigenic Escherichia coli is common.

What are the clinical signs of rotavirus infection in pigs?

Profuse, watery diarrhoea that can be pale yellow, with affected pigs becoming gaunt and rough-haired, but mortality is usually low

How is rotavirus infection diagnosed?

Virus isolation, IFAT, ELISA, serology

What is the main treatment for rotavirus infection in pigs?

No specific treatment; supportive treatment with oral electrolytes and oral antibiotics for secondary infections, such as neomycin

What is the prevention against rotavirus infections?

Improve hygiene, all-in-all-out, ensure colostrum intake, vaccinate dams before farrowing

What is postweaning multisystemic wasting syndrome (PMWS) in pigs?

A disease mostly affecting pigs 6-16 weeks old, characterised by a high mortality rate over 50% in pigs showing signs

What is the main agent causing postweaning multisystemic wasting syndrome (PMWS)?

Porcine circovirus type 2 (PCV-2)

What is the primary transmission route for postweaning multisystemic wasting syndrome (PMWS)?

Direct contact with infected pigs, semen, contaminated fomites, feeds, biologic products, multiple-use hypodermic needles, and biting insects

What is the pathogenesis of PMWS?

Infection with the virus over time → significant depletion of lymphocytes, changes in peripheral blood mononuclear cell subpopulations, & altered cytokine expression patterns.

This increases the risk of secondary infections, which is necessary for development of serious disease.

In the GIT it causes lesions very similar to Lawsonia spp. → proliferative enteropathy

Which pathologies are always present in PMWS?

Splenomegaly, gastric ulcers

What are the common clinical signs of postweaning multisystemic wasting syndrome (PMWS)?

Wasting, poor growth, emaciation, dyspnoea, pallor, anaemia, jaundice, diarrhoea, and enlarged lymph nodes

What are the clinical signs for subclinical PMWS?

No CS, in some cases retardation of growth may occur

What is the diagnosis method for postweaning multisystemic wasting syndrome (PMWS)?

Clinical signs, microscopic lesions, and the presence of PCV-2, with methods including serology, virus isolation, cell culture, ELISA, and PCR

What is the prevention method for postweaning multisystemic wasting syndrome (PMWS)?

Good management practices, as there is no specific treatment

What is the agent causing adenovirus infection in pigs?

Porcine adenovirus, a DNA virus

How is adenovirus transmitted?

Orofaecal, aerosol

What is the pathogenesis of adenovirus?

Replicates in tonsils, villous enterocytes & lymphoid tissue of small intestine. Piglets around 1-4 weeks old are mostly affected

What are the common clinical signs of adenovirus infection in pigs?

Mild, asymptomatic signs such as watery or pasty faeces, poor weight gain, mild dehydration, mild respiratory signs, and neurological symptoms

What is the diagnosis for adenovirus?

IFAT, CFT, VNT, ELISA, PCR, virus isolation, microscopy, histology – intranuclear inclusion bodies in cells of viscera

What is the treatment and prevention for adenovirus?

No treatment. Prevention by good hygiene

What is the classification of Enterovirus?

Enterovirus → Picornaviridae

Which diseases are enteroviruses associated with?

SMEDI, Teschen/Taflan encephalomyelitis

What is the primary transmission route for enteroviruses in pigs?

Oro-faecal and venereal transmission, including semen and aborted foetuses

What is the pathogenesis of enterovirus infection?

Multiplication in the small & large intestines. In absence of antibodies, the virus enters the body & later placenta, causing embryonal mortality, mummification & stillbirths, & neurological signs, depending on species

What are the clinical signs of enterovirus infection in pigs?

Signs include polioencephalomyelitis, female reproductive failure, myocarditis, pericarditis, pneumonia, and diarrhoea

What is the diagnosis for enterovirus infections?

Serology, virus isolation

What is the primary prevention for enterovirus infections in pigs?

Exposing gilts to the faecal bacteria of older sows one month before breeding

What do bovine viral diarrhoea and border disease cause?

Diarrhoea

What is vesicular syndrome in livestock?

A group of diseases caused by unrelated viruses with indistinguishable clinical signs, including FMDV, swine vesicular disease virus, and Indiana vesiculovirus

What is the transmission route for vesicular syndrome in livestock?

Direct contact via animal-animal or animal-object, as well as respiratory and oral routes

What are the common clinical signs of vesicular syndrome in livestock?

Blisters on the nose, tongue, lips, oral cavity, and between toes; ruptured blisters can lead to lameness and reluctance to eat or move. Possible myocarditis, encephalitis.

What is the diagnostic method for vesicular syndrome in livestock?

Virus isolation, PCR, ELISA, CFT, and virus neutralisation test

What is the prevention for vesicular syndrome in livestock?

Sanitary measures, including protection zones, quarantine, rodent control, slaughter, clean and disinfected premises, and vaccination in endemic areas

Which viruses can be prevented with the use of vaccines?

1. TGE

2. Rotavirus

3. FMD (endemic regions)