Disease Information (2) (Provided by Vesicular Diseases Lab, Foreign Animal Diseases Division) ( 07/05/11 ) | |||||
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Part | Charger | leeyh | date | 07/05/11 | |
Swine vesicular disease
1. Definition
Swine vesicular disease is a contagious disease of pigs, caused by an enterovirus and characterised by vesicles on the coronary bands, heels of the feet and occasionally on the lips, tongue, snout and teats.
2. Etiology
Virus family Picornaviridae, genus Enterovirus
Temperature: Preserved by refrigeration and freezing, inactivated by 56°C/1 hour
pH: Stable over a wide range of pH
Disinfectants: In the presence of organic matter, inactivated by sodium hydroxide (1% combined with detergent). For personal disinfection in the absence of gross organic matter, disinfectants, such as oxidising agents, iodophores, acids etc., are suitable if combined with detergent
Survival: Resistant to fermentation and smoking processes. May remain in hams for 180 days, dried sausages for >1 year, and in processed intestinal casings for >2 years
3. Host range
• Pigs
• Humans: laboratory personnel may seroconvert
4. Geographical distribution
• The disease has been recorded in Hong Kong, Japan and several European countries
• For detailed information on occurrence, see recent issues of World Animal Health
5. Transmission
• Virus readily infects via lesions in skin and mucosa. Direct contact or contact with excretions from in-fected pigs. Faecal contamination is a major source of virus spread, often within contaminated vehicles
• Meat scraps and swill derived from infected pigs
Sources of virus
• Intestinal tract is the primary site of infection
• All tissues contain virus during the viraemic period
• Epithelium from vesicles, vesicular fluid, faeces, and blood of sick animals
6. Incubation period
• Incubation period is 2-7 days
7. Gross lesions
• Vesicle formation is the only known lesion directly attributable to the infection
8. Diagnosis
Clinical diagnosis
The clinical signs of SVD may easily be confused with those of Foot and mouth disease (FMD)
• Sudden appearance of lameness in several animals in a group in close contact
• Elevation of body temperature by 2-4°C
• On hard surfaces, animals may be observed to limp, stand with arched back, or refuse to move even in the presence of food. Young animals are more severely affected
• Vesicles occur on the snout and along the coronary band and interdigital spaces of the feet, and rarely on the epithelium of the buccal cavity, the tongue and the teats
• Vesicle rupture results in erosions on the skin of the limbs and the coronary bands of the feet. Foot pads may be loosened. Pigs, particularly young stock, may lose the horny hoof
• Recovery occurs usually within 1 week, with a maximum of 3 weeks
• Some strains produce only mild clinical signs or are asymptomatic
Laboratory diagnosis
A. Identification of the agent
• ELISA
• Cell-culture isolation (pig-derived cell cultures)
B. Serological tests
• ELISA
• Virus neutralisation
9. Control and eradication
• No treatment
• No vaccination
A. Sanitary prophylaxis
• Strict quarantine
• Elimination of infected and contact pigs
• Prohibition of feeding with ship or aircraft garbage
• Thorough cooking of garbage
• Control of movement of pigs and vehicles used for transporting pigs
• Thorough disinfection of premises, transport vehicles, and equipment
B. Medical prophylaxis
• Laboratory workers should observe the same caution that applies to any microbiologically contaminated material that may have the potential to cause human infection
10. Public health aspects
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