Swine Vesicular Disease (SVD)

Swine vesicular disease (SVD) is a contagious disease of pigs, characterized by vesicles on the coronary bands, heels of the feet and occasionally on the lips, tongue, snout and teats.

Swine Vesicular Disease (SVD) may occur as subclinical, mild or severe, the latter usually only being seen when pigs are housed on abrasive floors in damp conditions.

The main importance of SVD is that it is clinically indistinguishable from foot and mouth disease (FMD), and any outbreaks of vesicular disease in pigs must be assumed to be FMD until investigated by laboratory tests and proven otherwise. However, subclinical infection has been the most frequent condition observed during recent years.

This disease was first reported in feeder pigs in Italy in 1966. It has since been reported in Great Britain (declared free in 1980), several European countries, and Asia.

Etiology

• The disease is caused by genus Enterovirus of family Picornaviridae.
• The virus contain only one serotype.
• The virus is antigenically related to human enterovirus B.
• The SVD virus is stable in an environment and pH range of 2.5–12.0.

Epidemiology

• The disease was first reported in Italy in 1966, and eradicated in most European countries in 1980.
• It has remained endemic in Italy.

Source of infection

• The virus excreted through nose and mouth occur upto 2 weeks, and faeces for 3 months.

Transmission

• Direct or indirect contact with an infected animals.
• Ingestion of contaminated pork and pork products.
• Through skin abrasion.

Clinical manifestation

• Incubation period is 2-7 days.
• Fever (temp 41^oC).
• Vesicles develop on coronary band particularly at the junction of heel rarely on the snout, dorsal surface of lips, tongue and teat.
• Lameness and off feed for few days.
• Lesion may be mild or inapparent when pigs kept on soft bedding.
• The affected animal usually recovered 2-3 weeks, and show dark horizontal line on the hoof.

Sample collection

• Faecal sample, vesicular fluid, affected skin and mucous membrane and whole blood.

Diagnosis

• Isolation of virus in porcine kidney cell culture.  Typical cytopathic effect is produced in 2 – 4 days of inoculation.
• Detection of SVD genome by ELISA or RT-PCR is same diagnostic value as virus isolation.
• The ELISA (indirect sandwich ELISA) and RT-PCR  may be suitable screening test for SVD.

Prevention and control

• Currently no vaccines are available.
• Prohibition of  feeding of uncooked garbage to pigs.
• Restriction of movement of pigs.
• Serosurveillance of pig farm to detect subclinical infection.
• Disinfection of premises with sodium hypochlorite.