38. Swine vesicular disease and vesicular exanthema of swine.

Question 1

Diseases caused By calcivirus?

Answer 1

Diseases caused by Caliciviruses

Caliciviridae family

• Vesivirus genus

• Vesicular exanthema of swine virus (VESV)
• Feline calicivirus

• Lagovirus genus

• Rabbit haemorrhagic disease virus (RHDV, RHDVa)
• Rabbit haemorrhagic disease virus 2 (RHDV-2)
• European brown hare syndrome virus (EBHSV)

• Norovirus genus

• Norwalk virus
• Porcine calicivirus

• Sapovirus genus

• Sapporo virus

• Nebovirus genus

• Newbury-1 virus

• Unassigned caliciviruses

• Porcine enteric calicivirus (PoCV)
• Mink calicivirus (MCV)
• Bovine enteric calicivirus (BoCV)
• Fowl calicivirus (FCVV)
• Canine calicivirus (CaCV)

• Characteristic

• 30-40nm diameter, icosahedral capsid (cup-shaped capsomers), +ssRNA genome, no envelope
• Resistant in the environment
• Relatively stenoxen viruses
• Isolation in cell culture is difficult or impossible
• Good antigens
• Distinct serotypes

Question 2

Swine vesicular disease Occurrence?

Answer 2

Swine Vesicular Disease (SVD)

Occurrence

• 1966 North Italy
• Sporadic
• OIE: no reported cases between 2015 and 2020
• Europe is free, sometimes imported ➝ 2007-2008 Portugal, Italy
• Hungary is free (occurred in 1974)

Question 3

Ethiology of swine vesicular disease?

Answer 3

Etiology

• SVD virus
• Enterovirus
• Coxsackie B5 virus of humans adapted to swine
• 1 serotype
• Only pigs susceptible
• Good resistance

‣ Faeces, meat

‣ Remains infective for several months

Question 4

Epidemiology of swine vesicular disease?

Answer 4

Epidemiology

• Spread

‣ Direct contact of swine ➝ discharge, faeces

‣ Raw pork, swill

• Shedding of virus

‣ Before appearance of clinical signs

‣ Lasts for 4 months

‣ Also asymptomatic carriers shed

• Indirect infection

Question 5

Pathogenesis of swine vesicular disease?

Answer 5

Pathogenesis

1. Infection per os
2. Epitheliotropic virus
3. Replication in the epithelium of the throat and gut
4. Viraemia

‣ Epithelial cells of mouth, snouts, teat, legs ➝ vesicles

‣ Heart, CNS ➝ asymptomatic or rare signs

‣ Foetus (rare)

5. Immune reaction

Question 6

Clinical signs of swine vesicular disease?

Answer 6

Clinical signs

• Incubation time: 2-7 days
• Fever for 1-2 days (41℃)
• Vesicles

‣ Nose (snout)

‣ Oral mucous membrane

‣ Legs ➝ damaged horn production

‣ Vesicles will be ruptured within 1-2 days

• Lack of appetite, limping
• Fast recovery
• Frequently asymptomatic

Question 7

Pathology, Diagnosis and differential diagnosis?

Answer 7

Pathology

• No gross pathologic lesions

Diagnosis

• Epidemiology ➝ clinical signs
• Laboratory examination always necessary ➝ also in direction of FMD (America vs VES)
• Detection of the virus

‣ RT-PCR, CFT, ELISA

‣ Virus isolation

• Detection of antibodies

‣ VN, ELISA

• Differential diagnosis

‣ Foot and mouth disease

‣ Vesicular exanthema of swine (VES)

‣ Vesicular stomatitis (VS)

‣ Vesicular disease caused by Senecavirus A

Question 8

Prevention of swine vesicular disease?

Answer 8

Prevention

• Notifiable disease in some countries (Hungary)
• Not OIE listed disease
• Prevention of introduction of agent

‣ Control of traffic of pigs and pork

‣ Ban of feeding with swill

‣ Rendering rest food

• In case of introduction

‣ Stamping out of infected herds

‣ Movement restriction

• There are no commercial vaccines

Question 9

Vesicular exanthema of swine History Occurrence?

Answer 9

Vesicular exanthema of swine (VES)

History, Occurrence

• 1932 California (atypical FMD)
• 1952-1956 USA spread with pork meat ➝ eradicated
• Later sporadic outbreaks in Hawaii and Iceland
• 1972 San Miguel sea lion ➝ identical with VESV
• Absent in swine but present in seals in the Pacific costal region of America

Question 10

Causative agent of vesicular exanthema of swine virus?

Answer 10

Causative agent

• Vesicular exanthema of swine virus (VESV, Vesivivirus genus)
• Seal is natural host ➝ Pig
• More than 20 serotypes, serological cross reactions
• Susceptible: pigs, seals, whales, dolphins, fish, fox, mink, monkeys, human ➝ detected from vesicles on face, hands

and feet

Question 11

Epizzotiology of vesicular exanthema of swine?

Answer 11

Epizootiology

• Primary source of infection: raw meat of sea mammals, fish
• Swine ➝ shedding with saliva, excretes
• Survives in the environment (in water) for at least 2 weeks
• Transmission with raw pork side-products
• Less contagious than FMD

Question 12

Clinical signs of vesicular exanthema of swine?

Answer 12

Clinical signs

• 1-4 days incubation
• Fever, anorexia, depression, vesicles: mouth, snouts, limbs
• Lameness
• Lesions heal rapidly
• Mortality in piglets
• Seals: skin lesions, abortion, perinatal mortality

Question 13

Diagnosis, differentation and control vesicular exanthema of swine?

Answer 13

Diagnosis

• Signs ➝ suspicion
• Not a notifiable disease but FMD is so laboratory diagnosis is necessary
• PCR, ELISA (isolation)

- Differentiation

‣ FMD in ruminants too

‣ SVD rare

‣ VS in horses and ruminants too, only in Americas

Control

• Outbreak: restriction zone, eradication, heat treatment of meat/disposal
• Prevention using heat treatment of seafood (fish meal) before fed to pigs

Question 14

Vesicular disease of swine caused by senecavirus?

Answer 14

Vesicular disease of swine caused by senecavirus

Etiology

• USA, China, Italy, Brazil
• Senecavirus A (Seneca Valley virus)

Epidemiology

• Infection with discharge
• Indirect infection

Clinical signs

• Piglet (under 1 week) ➝ fever, depression, salivation, diarrhoea, CNS signs
• Grower, fattening pigs ➝ vesicles on the coronary band, leg

Pathology

• Piglet ➝ inflammation of the oral mucosa, interstitial pneumonia, encephalitis
• Adults ➝ do not die

Diagnosis

• Epidemiology ➝ clinical signs ➝ pathology
• Detection of virus ➝ IF, PCR
• Detection of antibodies ➝ iIF, ELISA

Prevention, Control

• General epidemiological measures
• Movement restriction