Pesti Porcine Africaine, Peste Porcina Africana, Maladie de Montgomery
Species Affected: Domestic pigs, Feral swine, Wild pigs
-Eurasian wild boars, Warthogs (reservoir), Bush pigs (reservoir), Giant forest hogs
------------------------------------- 【 The Organism】 ------------------------------------------
African Swine Fever Virus
Asfarviridae: Asfivirus
-Large, enveloped DNA virus
-Only arbo-DNA virus
More than 20 genotypes
-Vary in virulence
-High virulence: up to 100% mortality
-Low virulence: seroconversion
Infects monocytes and macrophages
Highly resistant in environment, especially at lower temperatures
Survival
Several days in feces
Month(s) in contaminated pens
Up to 18 months in blood
Over 140 days in some pork products-Salted dried hams
Years in frozen carcasses
Virus Inactivation
Most disinfectants ineffective
Disinfectants on nonporous surfaces-Sodium hypochlorite, citric acid, some iodine and quaternary ammonium solutions
Meat/tissue products-High temp (70oC/150oF) for 30 min
Can be inactivated -pH below 3.9 or above 11.5, Higher pH needed if serum present
-------------------------------- 【 History and Importance】------------------------------------
History
1921: Discovered in Kenya
Today: endemic in most of sub-Saharan Africa including the island of Madagascar
1957: First occurrence outside Africa - Portugal
1960s: Portugal and Spain
1970-1980s: Spread to Europe, The Netherlands, Italy, France, Belgium
1990s: Disease eradicated
Remains endemic on the Island of Sardini
History : Tick Vector
1963: Virus isolated from soft tick
Ornithodoros erraticus
1971: Western Hemisphere
Cuba, the Dominican Republic, Haiti, Brazil
Eradicated
2007: Republic of Georgia
Spread in Caucasus Region (Eurasia), including Russia Federation
2015: Eastern Europe: Lithuania, Latvia, Poland, Romania
Wild boar in Iran
2018 Outbreaks
China: First time reported, domestic pigs
Belgium: Wild boars
Hungary, Estonia, Latvia, Lithuania, Russia, Poland, Ukraine, Bulgaria, Romania
Virus Introduction for Outbreaks
Uncooked/undercooked pork products fed to pigs (imported, illegal)-Portugal , Spain (1960); Italy (1983); Belgium (1985); Russia (2008); Romania, China (2018)
Raw pork waste/garbage at airport or shipping ports-Lisbon (1957), Malta, Sardinia (1978), Georgia (2007)
Movement of infected wild boars-Russia (2008)
Economic Impact
Animal health (High morbidity and mortality, Highly contagious)
Import and export bans
Movement restrictions
Quarantine and depopulation
Can become prolonged epidemic
------------------------------------------- 【Epidemiology】 --------------------------------------
Geographic Distribution
Endemic
Sub-Saharan Africa , Island of Sardinia (feral swine)
Continued outbreaks
-Central and Eastern Europe
Poland, Czech Republic, Hungary, Romania, Ukraine
-Eurasia: Russia, Caucasus
-Belgium
Never been reported in United States, Canada, Mexico, Australia, New Zealand
Reported Outbreaks
OIE: Jan-Sept 2018
Morbidity and Mortality
-Morbidity up to 100% (Previously unexposed herds)
-Mortality varies with genotype virulence
Ranges from <5% to 100%
-All ages affected
-Subacute mortality = 30% to 70%
-May be asymptomatic in wild pigs
------------------------------------------【Transmission】-----------------------------------------
-Direct contact with infected pig (Usually oronasal; All secretions/excretions, blood, tissues; Environmental contamination with products)
-Ingestion of contaminated pork products (Fed to pigs – swill, waste, garbage; Carcasses)
Fomites
Clothing, vehicles, equipment
Environmental contamination (Blood, diarrhea, feces)
Vectors
Biological: Bite from soft ticks Ornithodoros
Mechanical: Other insects-Mosquitoes, biting flies (Stomoxys)
Ornithodoros soft ticks
Transstadial
Transovarial
Sexual transmission
Infected for life
Colonies maintain virus for years
Tick-to-pig transmission
Important in Africa
Maintained between warthogs and tick
Humans are not susceptible to African Swine Fever
There is no public health or food safety concern.
-------------------------------【African Swine Fever in Animals】-----------------------------
Clinical Disease
Incubation period
5-21 days following direct contact, < 5 days after tick bite
Forms of disease
Peracute – sudden death, Acute, Subacute, Chronic
Clinical Signs: Acute Disease
High fever, Anorexia, Lethargy, Weakness, recumbency
Erythema, cyanosis, Hemorrhages, Skin, snout
Diarrhea, Abortion, Respiratory, Dyspnea, Nasal discharge, Death, 7-10 days
Clinical Signs: Subacute Disease
Moderately virulent isolates
Similar signs to acute form, but less severe
Abortion , Fever, Erythema, cyanosis, Hemorrhages may occur, Thrombocytopenia, Leukopenia, Death or recovery within 3-4 weeks
Clinical Signs: Chronic Disease
Intermittent, low fever, Anorexia, depression, Emaciation, stunting
Respiratory: coughing, Joint swelling
Diarrhea, Occasional vomiting, Skin lesions, May be fatal
Post-Mortem Lesions
Numerous hemorrhagic internal organs
Skin
Discoloration
Hemorrhages
Signs of bloody diarrhea or internal hemorrhages
Spleen
Enlarged, Friable, Dark red/ black
Post-Mortem Lesions: Most Common
Lymph nodes (Swollen, Hemorrhagic)
Gastrohepatic and renal LN common
Tonsils: swollen, reddened
Kidneys:
Petechiae on cortical and cut surfaces
Perirenal edema possible
Other organs
Hemorrhages, petechiae, ecchymoses
Edema: Lungs, gall bladder
Brain/meninges: Congested, edema
Post Mortem Lesions: Chronic Infection
Focal skin necrosis, Skin ulcers, Consolidated lung, Caseous pneumonia
Fibrinous pericarditis, Pleural adhesions, Lymphadenopathy, Swollen joints
Differential Diagnosis
Classical swine fever (hog cholera) , Acute PRRS
Porcine dermatitis and nephropathy syndrome
Erysipelas, Salmonellosis, Eperythrozoonosis, Actinobacillosis
Glasser’s disease, Aujeszky’s disease (pseudorabies)
Thrombocytopenic purpura, Warfarin poisoning, Heavy metal toxicity
Sampling
Before collecting or sending any samples, the proper authorities should be contacted
Samples should only be sent under secure conditions and to authorized laboratories to prevent the spread of the disease
Actions To Take
Reportable disease
If ASF suspected, IMMEDIATELY notify local animal health authorities
Isolate/quarantine animals until definitive diagnosis received
Diagnosis
Virus isolation(Blood, tissues)
PCR
Clinical samples, putrefied samples, fresh tissues/blood
Tonsils for FAD investigation
Serological (ELISA, Immunoblotting, Indirect fluorescent antibody (IFA) , Smears, cryostat, buffy coat, Endemic regions)
Treatment
No treatment available
No treatment should be attempted
No vaccine available
Response should be directed by animal health authorities
Depopulation
Restrictions on pig movements
------------------------------------------【Prevention】-------------------------------------------
Prevent indirect transmission
Do not feed uncooked pork products to pigs
Swill, garbage, waste
Disinfection
Vehicles, equipment, footwear, clothing
Appropriate disposal of manure and carcasses
Avoid hunting wild hogs prior to contact with domestic pigs
Prevent vector transmission
Control tick and other insect vectors
May be difficult in endemic areas
Prevention - from Staff Daily Operations
Don't own other pigs or come in contact with other hogs: Many times when animals first pick up a disease, they may be shedding the organisms before they show clinical signs. By avoiding contact with other pigs, employees help ensure that accidental cross contamination from one group of pigs to the other is minimized.
Leave valubles at home: It is difficult to clean jewelry while hand washing or showering to ensure removal of potential infectious diseases. It is better to leave them at home.
Stay home when you are sick: Employees may infect pigs with zoonotic diseases, including the flu.
Prevention - How to protect your herd
Wash hands or shower-in/shower-out: Hand washing should be done with soap for at least 30 seconds. If you have shower facilities, follow correct biosecurity by removing all items on the dirty side, showering, and dressing with only items on the clean side. Eyewear should be cleaned in shower before entering clean side.
Wear clean coveralls and boots on each side: Having clean coveralls and boots at each site limits the spread of disease if anyone needs to move between sites.
Eating is prohibited in animal areas: Keep any food in a breakroom or office if it is necessary to bring the food into the building. Disease can be brought onto a site in meat products if those products are carried into animal areas.
Respect clean and dirty areas when loading animals: Personnel and equipment in the clean area must stay on the “clean” side while the truck drive and any loading equipment from his truck must remain on the “dirty” side.
Do not share equipment between sites; or clean, disinfect, and allow equipment to dry if sharing is absolutely necessary. Patheogens can survive on equipment and infect the next group of pigs.
Clean and disinfect equipment between pigs or groups when possible: Even processing equipment can carry disease from one pig/one litter to the next if the instruments are not allowed sufficient contact time in a disinfectant.
Respect clean and dirty areas when loading animals: Personnel and equipment in the clean area must stay on the “clean” side while the truck drive and any loading equipment from his truck must remain on the “dirty” side.
Follow farm policy for downtime following international travel: Depending on what country you traveled to, and what activities you participated in, your post-trip procedures may be affected upon your return.
Clean and disinfect equipment between pigs or groups when possible: Even processing equipment can carry disease from one pig/one litter to the next if the instruments are not allowed sufficient contact time in a disinfectant.
Prevention - Traveling Overseas
Before and during your trip:
■ Determine if personnel from the international farm you plan to visit will provide you with site-specific footwear and coveralls or clothing during your visit.
■ Pack disposable coveralls and footwear to wear during international farm visits if items will not be provided.
■ Do not wear footwear on your trip that you wear to your farm.
■ Know which items you are allowed to bring back with you into the U.S. Prohibited foods may carry diseases which pose a risk to domestic livestock.
Upon your return:
• Follow farm biosecurity measures upon your return. Follow the farm downtime requirements. If there are no set requirements, 48 hours is a minimum downtime as long as a shower is taken and clean clothes are worn to the site. Farm biosecurity measures may vary. Make sure to follow the biosecurity measures on the farm.
• Do not wear any items from your international farm visit to your farm or a local farm. A small amount of fecal matter can transmit disease. Even machine washing in hot water may not ensure footwear is clean because fecal matter can remain in the tread. Not wearing this footwear to your farm ensures you are not taking any unnecessary risk of bringing disease back to work with you.
Prohibit visitors from bringing any food items to the farm. Diseases can be carried in undercooked food products.
• Prohibit personal items that cannot be disinfected from entering the facility. Personal items such as cell phones and jewelry can be contaminated. If the item cannot be disinfected, it should be left in the vehicle.
• Prevent animal contact by visitors. Keep visitors out of animal pens to reduce the possibility of disease transmission to the animals.
An employee should verify the following biosecurity measures are followed on the farm:
Restrict visitors to those with a verified need to be there.
Discuss with visitors the need to follow the farm downtime requirements. If there are no set requirements, 48 hours is a minimum downtime.
Instruct visitors to shower prior to their arrival and to wear clean clothes and footwear to the site.
Provide a designated parking area for visitors that is clearly marked and located away from animal areas. Instruct visitors to park in the designated parking area upon arrival.
Have an escort available to stay with the visitor to ensure that the visitor stays out of restricted areas and follows all biosecurity measures.
Provide site-specific coveralls or clothing and boots for visitors to wear onsite.
Instruct visitors that food items are prohibited.
Inform visitors that any personal items that cannot be disinfected are prohibited. They should leave valuables in their car.
-------------------------------------------【Control】-------------------------------------------
Control Measures
Quarantine of farm
Authorities notified
Movement restrictions
Investigation
Rapid diagnosis
Determine source of virus
Disinfection
Many disinfectants ineffective
Use an product approved for the virus
Feces and organic debris can increase resistance of virus
Disinfectants on nonporous surfaces
Sodium hypochlorite, citric acid, some iodine and quats
Disinfect premises, equipment, vehicles, footwear
Eradication
Euthanize/depopulation of infected and in-contact animals
Proper carcass disposal
To avoid further spread
Sanitation/disinfection
Movement controls/quarantines
Avoid contact with wild suids
Additional Resources
CFSPH Technical Factsheet - African Swine Fever http://www.cfsph.iastate.edu/Factsheets/pdfs/african_swine_fever.pdf
USDA FAD PReP Disease Response Strategy for African Swine Feverhttps://www.aphis.usda.gov/animal_health/emergency_management/downloads/asf_strategies.pdf
OIE Technical Disease Card: African Swine Feverhttp://www.oie.int/en/animal-health-in-the-world/animal-diseases/african-swine-fever/
USAHA Foreign Animal Diseases (“The Gray Book”)http://www.aphis.usda.gov/emergency_response/downloads/nahems/fad.pdf
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