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PATHOGEN SAFETY DATA SHEET

AFRICAN SWINE FEVER

SECTION I: DISEASE / INFECTIOUS AGENT

SYNONYM / CROSS REFERENCE: Pesti porcine Africaine, maladie de Montgomery ⁽¹⁾, African Pig Disease, Wart Hog Disease, ASF ⁽²⁾

ETIOLOGY / TAXONOMY:
Family: Asfaviridae ⁽³⁾ (formerly classified in family Iridoviridae ^{(1, 3)})
Genus: African Swine Fever Virus (characteristics of Poxvirus)

ORGANISM CHARACTERISTICS:
large lipoprotein-enveloped icosahedral, double stranded DNA virus (about 200 nm) ^{(1, 2)}

SURVEILLANCE:

• African Swine Fever is a reportable disease in Canada. Animal owners, veterinarians and laboratories are required to immediately report the presence of an animal that is contaminated or suspected of being contaminated to a CFIA district veterinarian. Control or eradication measures will be applied immediately (http://laws.justice.gc.ca/en/H-3.3/fulltoc.html).

DISTRIBUTION:

• The status of African Swine Fever in Canada is non-indigenous.
• Until 1957, ASF had not occurred outside the African continent ⁽²⁾.
• ASF spread from Africa appearing in the domestic pig population in Portugal in 1957 and Spain in 1960 ^{(2, 4)}.
• The disease then appeared in France and then Italy and in 1971 occurred in Cuba. It was successfully eradicated from these countries by extensive slaughter and control programs.
• In 1978, outbreaks occurred in Malta, Sardinia, Brazil, Dominican Republic and Haiti. In Malta the disease resulted in the death or slaughter of the entire population of 80,000 pigs within 12 months of the diagnosis ⁽²⁾.
• In March 1985, an outbreak occurred in Belgium and was eradicated in September 1985 and the Netherlands 1986 ^{(2, 4)}.
• The latest outbreaks were reported in Burkina Faso, Congo, Nigeria, Senegal and Tanzania between July 2003 and September 2004 ⁽⁵⁾.

SECTION II: ANIMAL HEALTH HAZARD AND EPIDEMIOLOGY

CLINICAL DISEASE / PATHOGENESIS: ^(1-3)
1) Clinical signs:
Peracute form:

• found dead - without clinical signs
• may be moribund - high fever

Acute form:

• highly virulent form
• fever of 40.5 -42 C
• clinical signs 1-2 days after onset of fever
• reddening of skin - tips of ears, tail, distal extremities, ventral chest and thorax - turns to cyanosis
• increased pulse, respiration; vomiting, diarrhea
• survivors are “carriers” for life
• mortality in domestic swine - approach 100%

Subacute form:

• moderately virulent
• symptoms less intense - duration 5 - 30 days
• fever fluctuates up to 20 days
• abortions
• mortality varies 30 - 70%

Chronic form:

• weight loss, necrosis of skin, chronic skin ulcers
• irregular fever spikes
• develops over 2 - 15 months
• stunted growth, emaciated
• may develop chronic pneumonia, lameness
• low death loss

2) infectious dose: unknown

3) incubation period: varies from 48-72 hours after contact exposure ⁽¹⁾

SOURCE / MODE OF TRANSMISSION / COMMUNICABILITY:

• The disease is primarily transmitted from the reservoir in wild pigs to the domestic pigs via argasid tick Ornithodoros moubata ⁽²⁾. The tick is relatively restricted in its habitat and if contact between domestic pigs and wild pigs and their burrows is prevented, transmission can be prevented as well ⁽²⁾.
• Infection occurs via oral and nasal routes and with the short incubation period once the disease is established in a herd, it spreads rapidly by direct contact and by contact with contaminated clothing, feed, vehicles and equipment ⁽²⁾.
• The virus can persist in the blood of some recovered pigs for 8 weeks and in the lymphoid tissues for 12 weeks. Carrier state survivors will re-infect environment ⁽¹⁾.
• Primary method of spread from country to country has been through the feeding of uncooked garbage containing ASF virus infected pork products to susceptible pigs ⁽¹⁾.

VECTORS:

• The African vector is Ornithodoros moubata. The virus is maintained primarily by a cycle of infection between wart hogs and soft ticks. The virus can be maintained in these ticks for long periods in the absence of fresh sources of infection, so that they act as reservoir as well as vectors of infection ⁽²⁾.
• The European vector is the soft tick O. erraticus. It can maintain and transmit the virus for at least 300 days ⁽²⁾.
• The North America and Caribbean Basin potential vectors are O. coridaceus and O. puertoricensis ⁽²⁾.

HOST RANGE:

• Domestic and wild pigs (Africa: warthog, bush pig and giant forest hog; Europe: feral pig) were initially thought to be the only hosts of ASF virus ⁽¹⁾.
• ASF virus in wild pigs in Africa is now believed to cycle between soft ticks living in warthog burrows and newborn warthogs. Many researchers believe that ASF virus is really a tick virus and the pig is an accidental host ⁽¹⁾.

ZOONOTIC POTENTIAL:
ASF virus cannot be transmitted to humans.

RESERVOIR:

• domestic pigs
• wart hogs
• bush pigs
• forest hogs
• ticks Ornithodoros moubata

Section III: DIAGNOSIS

NECROPSY / HISTOPATHOLOGY FINDINGS:

• Signs vary with the form of the disease.
• The highly virulent form ASF virus may have poorly developed lesions ⁽¹⁾
• There may be very enlarged and hemorrhagic gastrohepatic and renal lymph nodes, subcapsular petechiation of the kidneys, ecchymoses of the cardiac surfaces and various serose, and pulmonary edema with hydrothorax ^{(1, 2)}.
• The gallbladder is edematous and hemorrhagic and severe submucosal congestion in the colon are usually seen when pigs are infected with ASF ^{(1, 2)}.
• The spleen is greatly enlarged, dark red and friable ⁽¹⁾
• Histologically, the virus causes destruction of the mononuclear phagocytes system and then infects megakaryocytes, tonsillar crypt cells, renal cells, hepatocytes and endothelial cells ⁽²⁾.

SAMPLE SUBMISSION:

• Whole blood
• Serum
• Fixed and fresh tissues

All samples should be transported at 4°C.

For more information regarding the type of samples necessary for ASF diagnosis, please contact the National Center for Foreign Animal Disease:

LABORATORY DIAGNOSIS:

• cell culture
• virus isolation
• ELISA
• fluorescence antibody technique (FAT)
• immunoblotting assay
• PCR
• electron microscopy
• animal inoculation

DRUG SUSCEPTIBILITY: none

DIFFERENTIAL DIAGNOSIS:
The following diseases may show clinical similarity to ASF.

• Hog cholera (classical swine fever)
• Aujeszky`s disease
• Erysipelas
• Acute salmonellosis
• Viral encephalomyelitis
• Pasteurellosis - pneumonia
• Warfarin poisoning
• Heavy metal poisoning

SECTION IV: DECONTAMINATION PROCEDURES

Select a registered disinfectant with a drug identification number (DIN). Use according to label directions for concentration and contact time. Consider organic load and temperature. It is recommended that laboratories evaluate the effectiveness of the disinfectant using a validated method (eg. Quantitative Carrier Test). See table 1 to help select a registered disinfectant for use against ASF virus.

Table 1 : Active ingredients considered to be effective against ASF virus.

PHYSICAL INACTIVATION:

SURVIVAL OUTSIDE OF HOST:

• The virus is very resistant to putrefaction, heat and dryness and survives in chilled carcasses for up to 6 months ⁽²⁾.
• The virus will survive for 15 weeks in putrefied blood, 3 hours at 50°C, 70 days in blood on wooden boards, 11 days on feces held at room temperature, 18 months in pig blood held at 4°C and 150 fays in boned meat held at 39°F ⁽¹⁾.
• ASF virus is stable between pH 4 and 10 ⁽⁶⁾.
• In serum, virus can resist pH 13.4 for 7 days ⁽⁵⁾.

SECTION V: LABORATORY HAZARDS FOR HUMANS

LABORATORY-ACQUIRED INFECTIONS: none

BIOSAFETY PRECAUTIONS : none

SECTION VI: PHYSICAL AND OPERATIONAL REQUIREMENTS

CONTAINMENT REQUIREMENTS:
All physical containment and operational practices for containment level 3, non-indigenous agents, as per the Containment Standards for Veterinary Facilities must be met. The Standards can be accessed at : http://www.inspection.gc.ca/english/sci/lab/convet/convete.shtml

PROTECTIVE CLOTHING:
Laboratory:

• Primary layer of protective clothing should include dedicated laboratory clothing (eg. scrubs and headwear) and laboratory dedicated footwear.
• Secondary layer of protective clothing (eg. solid-front gowns with tight-fitting wrists, 2 pairs of gloves) should be worn over laboratory clothing when directly handling infectious materials.
• A risk assessment should be conducted to determine if a respiratory protection is required when directly handling infectious material outside BSC.
• A shower is required on exit.

Post Mortem:

• Primary layer of protective clothing should include dedicated laboratory clothing (eg. scrubs and headwear) and laboratory dedicated footwear.
• Secondary layer of protective clothing (eg. solid-front gowns with tight-fitting wrists, 2 pairs of gloves) should be worn over laboratory clothing when directly handling infectious materials.
• Cut resistant gloves, adequate respiratory protection, steel toed/steel shanked rubber boots should also be worn when handling infectious materials.
• A shower is required on exit.

HANDLING INFORMATION :
Spills in laboratory:
Spill protocol must be in place and include the following scenarios:

• spills inside the Biological Safety Cabinet (BSC)
• spills outside the BSC
• spills while performing aerosol generating procedures
• also consider entry and exit procedure modifications if necessary, appropriate PPE, disinfection of spill and surroundings including contact time, flow (pattern) of the clean up and disposal of contaminated materials.

Refer to Table 1 for disinfectant selection.

STORAGE: All cultures and infected material should be stored in leakproof, sealed containers that are accurately labeled and clearly identified as a biohazard risk. The access to infectious material should be controlled at all times. Records must be kept to describe the use, inventory and disposal of infectious material.

DISPOSAL: Decontaminate all infectious material prior to disposal. Use steam sterilization, incineration or chemical disinfection.

REFERENCES:

1. Committee on Foreign Animal Diseases of the United States Animal Health Association. Foreign Animal Diseases. Revised 1998, Library of Congress Catalog Card Number, 17-12842, Pages 41-51.
2. Radostits, O.M. Gay, C.C. Blood, D.C. & K.W. Hinchcliff. Veterinary Medecine, A Textbook of the Disease of Cattle, Sheep, Pigs, Goats and Horses. Ninth Edition. W.B. Saunders Company Ltd. 2000. Pages 1038-1039.
3. Stasiak K, Renault S, Demattei MV, Bigot Y, Federici BA. Evidence for the evolution of ascoviruses from iridoviruses. J Gen Virol. 2003 Nov;84(Pt11):2999-3009.
4. Australian Veterinary Emergency plan, 1996, Disease Strategy, African Swine Fever, http://www.animalhealthaustralia.com.au/shadomx/apps/fms/fmsdownload.cfm?file_uuid=2B20BCF4-9B70-3DC3-0E8B-B39C2DD0E38F&siteName=aahc
5. OIE, Disease Information : http://www.oie.int/eng/info/hebdo/a_dsum.htm
6. The Merk Veterinary Manual, African Swine fever sheet: http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/53200.htm&word=african%2cswine%2cfever
7. Australian Veterinary Emergency Plan. Operational Procedures Manual: Decontamination. 2000.

LAST UPDATED (DATE): March 29, 2005
PREPARED BY: The Biohazard Containment and Safety Unit, CFIA

Disclaimer: Although the information and recommendations in this Pathogen Safety Data Sheet are compiled from reliable sources, there is no guarantee, warranty or any assurance that the information and recommendations are correct, accurate, sufficient, reliable or current and the Canadian Food Inspection Agency shall not be responsible for any loss or damage resulting from or in connection with the use of or reliance upon the information and recommendations.

The user assumes all risks and responsibility for and shall be liable for the use of and any reliance on the information and recommendations and the results thereof and any loss or damage resulting therefrom.

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