African Swine Fever 2006 African Swine Fever 2006 African Swine Fever African Swine Fever Texas A&M University Texas A&M University College of Veterinary Medicine College of Veterinary Medicine Jeffrey Musser, DVM, PhD, DABVP Jeffrey Musser, DVM, PhD, DABVP Suzanne Burnham, DVM Suzanne Burnham, DVM
84
Embed
Texas A&M University College of Veterinary Medicine Swine Fever.pdfTexas A&M University College of Veterinary Medicine Jeffrey Musser, DVM, PhD, DABVP Suzanne Burnham, DVM. ... –
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
African Swine Fever 2006African Swine Fever 2006
African Swine Fever African Swine Fever
Texas A&M University Texas A&M University
College of Veterinary MedicineCollege of Veterinary Medicine
M. van Vuuren, Dept. of Veterinary Tropical Diseases,
Faculty of Veterinary Science University of Pretoria
Corrie Brown, DVM, PhD Department of Veterinary
Pathology College of Veterinary Medicine University of
Georgia
Tom McKenna, DVM, PhD USDA, “Swine Fevers”
Colorado State FEAD Course Aug. 1-5, 2005
Plum Island Animal Disease Center, Kathy
Appicelli, Photographer
African Swine Fever 2006African Swine Fever 2006
African Swine FeverAfrican Swine Fever
African Swine Fever 2006African Swine Fever 2006
African Swine FeverAfrican Swine Fever
African Swine Fever African Swine Fever
is a tickis a tick--borne, contagious, borne, contagious,
febrile, systemic viral febrile, systemic viral
disease of swinedisease of swine
http://www.iah.bbsrc.ac.uk/images/Asfvirus.gif
African Swine Fever 2006African Swine Fever 2006
African Swine FeverAfrican Swine Fever
Highly contagious viral disease of domestic pigs Highly contagious viral disease of domestic pigs with up to 100% mortalitywith up to 100% mortality
Pigs die as a result of a hemorrhagic feverPigs die as a result of a hemorrhagic fever
African Swine Fever 2006African Swine Fever 2006
Some pigs may Some pigs may develop develop subacutesubacute or or chronic forms of the chronic forms of the diseasedisease
Control depends on Control depends on the slaughter and the slaughter and destruction of all destruction of all infected and ininfected and in--contact contact pigspigs
African Swine Fever 2006African Swine Fever 2006
There is no vaccine for There is no vaccine for
African Swine FeverAfrican Swine Fever
African Swine Fever 2006African Swine Fever 2006
Disease reported present
Disease reported absent
Data unavailable or incomplete
African Swine FeverAfrican Swine FeverIs a serious Is a serious transboundarytransboundary animal disease animal disease
with the potential for rapid international spreadwith the potential for rapid international spread
World Distribution in 2004
African Swine Fever 2006African Swine Fever 2006
African Swine Fever African Swine Fever
EtiologyEtiology
Host rangeHost range
Incubation Incubation
Clinical signsClinical signs
TransmissionTransmission
Diagnosis Diagnosis
Differential DiagnosisDifferential Diagnosis
African Swine Fever 2006African Swine Fever 2006
Etiology Etiology
The ASF virus is theThe ASF virus is theonly member of the genus only member of the genus asfivirusasfivirus in the family in the family AsfarviridaeAsfarviridae*.*.
Large (~ 200 nm) Large (~ 200 nm)
lipoproteinlipoprotein--enveloped, enveloped,
icosahedral, icosahedral,
doubledouble-- stranded DNA virusstranded DNA virus
ASFV is the only DNA virus ASFV is the only DNA virus
that can qualify as an that can qualify as an
arbovirusarbovirus. .
* “ASFAR”
AfricanSwine
FeverAnd
Related viruses
African Swine Fever 2006African Swine Fever 2006
ASFV is a large, dsDNA, enveloped virus recently
classified in the new family
Asfarviridae
Rare example of a DNA
arthropod-borne virus
The stability of the virus is a
notable feature:
Infectivity is retained after 15
weeks in chilled meat, and for
5-6 months in processed
hams
Etiology
African Swine Fever 2006African Swine Fever 2006
Strain Virulence
Marked variations in virulence of isolates:
- Highly virulent - 10-100 % mortality by 7-10
days after exposure;
- Moderately virulent - Acute illness, a high % of
pigs survive;
- Low virulence - Seroconversion only.
African Swine Fever 2006African Swine Fever 2006
Environmental Persistence
Stable at pH 4Stable at pH 4--1313
Survives at least:Survives at least:
-- 11 days in feces (room temp)11 days in feces (room temp)
-- 1 month in soiled pig pens1 month in soiled pig pens
-- 70 days in blood on wooden boards70 days in blood on wooden boards
-- 15 weeks in putrefied blood 15 weeks in putrefied blood
-- 18 months in blood at 418 months in blood at 4ooCC
African Swine Fever 2006African Swine Fever 2006
Environmental Persistence
Survival in pork productsSurvival in pork products::
15 weeks in chilled meats15 weeks in chilled meats
300 days in cured hams (300 days in cured hams (““Parma hamsParma hams””))
15 years in frozen carcasses15 years in frozen carcasses
African Swine Fever 2006African Swine Fever 2006
Host RangeHost Range
OrnithodorosOrnithodoros ticks are believed to be ticks are believed to be
the original hostthe original host
African Swine Fever 2006African Swine Fever 2006
Host RangeHost Range
Soft ticksSoft ticks-- Ornithodorus erraticusOrnithodorus erraticus from ASFfrom ASF--infected infected
farms.farms.
-- Ornithodorus porcinusOrnithodorus porcinus porcinus (moubata)porcinus (moubata) from from
warthog burrows.warthog burrows.
-- OrnithodorusOrnithodorus ticks in Haiti, Dominican Republicticks in Haiti, Dominican Republic
and California.and California.
African Swine Fever 2006African Swine Fever 2006
Host RangeHost Range
ASFV is believed to be a tick virus with ASFV is believed to be a tick virus with
domestic pigs and wild pigs as accidental domestic pigs and wild pigs as accidental
–– Despite high fever, ASF Despite high fever, ASF
infected pigs stay in good infected pigs stay in good
condition, whereas hog condition, whereas hog
cholera infected pigs cholera infected pigs
drastically lose weightdrastically lose weight
African Swine Fever 2006African Swine Fever 2006
Some groups of pigs Some groups of pigs may develop diarrhea, may develop diarrhea, but it is not a direct effect but it is not a direct effect of the virus.of the virus.
Pigs may also develop Pigs may also develop dark red to purple dark red to purple discoloration of skin on discoloration of skin on ears, tail, extremities, or ears, tail, extremities, or skin on hams. skin on hams. (This is a (This is a nonspecific sign also seen in other nonspecific sign also seen in other diseases)diseases)
http://www.spc.int/rahs/Manual/images/asf-03.jpg
General Clinical SignsGeneral Clinical Signs
African Swine Fever 2006African Swine Fever 2006
AbortionAbortion
Occurs whether isolates are high, Occurs whether isolates are high,
moderate or low in virulence.moderate or low in virulence.
-- Fetuses may be anasarcous.Fetuses may be anasarcous.
-- May find petechiae in placenta, skin, andMay find petechiae in placenta, skin, and
myocardium, and a mottled liver. myocardium, and a mottled liver.
From 8From 8--12 DPI 12 DPI -- Gross lesions are similar whether pigs are Gross lesions are similar whether pigs are infected with a moderately virulent or highly infected with a moderately virulent or highly virulent ASFV. virulent ASFV.
The main difference between these two The main difference between these two types of isolates:types of isolates:-- Splenomegaly is still present,Splenomegaly is still present,-- More normal color and is not friable. More normal color and is not friable.
African Swine Fever 2006African Swine Fever 2006
Chronic ASF: Chronic ASF:
Necrotic skin lesionsNecrotic skin lesions
Raised reddened areas with central areas of necrosis
Raised reddened area behind the ear.
African Swine Fever 2006African Swine Fever 2006
Gross LesionsGross Lesions
Low Virulent VirusLow Virulent VirusThe most common The most common
lesions in chronic ASFlesions in chronic ASF::
--Necrotic skin lesions Necrotic skin lesions
--Consolidated lung Consolidated lung
lobules lobules
--Generalized Generalized
lymphadenopathy lymphadenopathy
--Swollen jointsSwollen joints
--PericarditisPericarditis
African Swine Fever 2006African Swine Fever 2006
Epidemiology:Epidemiology:
Sylvatic cycle in AfricaSylvatic cycle in AfricaInfected Argasid ticks in warthog Infected Argasid ticks in warthog burrowsburrowstransmit virus to young warthogs. transmit virus to young warthogs. -- Pigs remain infected for life.Pigs remain infected for life.-- Transtadial, transovarial, sexual Transtadial, transovarial, sexual transmission.transmission.
Pigs can be raised successfully in Pigs can be raised successfully in confinement with double fencing, confinement with double fencing, proper isolation, and sanitary proper isolation, and sanitary procedures.procedures.
African Swine Fever 2006African Swine Fever 2006
Epidemiology:Epidemiology:
Epidemic cycleEpidemic cycleIntroduction into domestic swine by Introduction into domestic swine by feedingfeedinggarbage / swill contaminated with pork garbage / swill contaminated with pork scraps.scraps.
Wild Wild suidssuids in Africa are carriers of the virusin Africa are carriers of the virus
Acquire the virus from Acquire the virus from OrnithodorosOrnithodoros moubatamoubata that invade that invade warthog burrowswarthog burrows
Young warthogs become infected as neonates and retain Young warthogs become infected as neonates and retain high viral titres for up to about 3 weekshigh viral titres for up to about 3 weeks
Where ASF becomes endemic in domestic pigs, the virus Where ASF becomes endemic in domestic pigs, the virus is maintained by carrier pigsis maintained by carrier pigs
African Swine Fever 2006African Swine Fever 2006
TransmissionTransmission
Warthog burrowWarthog burrow
African Swine Fever 2006African Swine Fever 2006
TransmissionTransmission
Ingestion Ingestion �� Tonsil Tonsil �� Local LNs Local LNs �� Viremia Viremia
Virus in excretions and secretions, blood.Virus in excretions and secretions, blood.
Carrier pigs incriminated in maintaining Carrier pigs incriminated in maintaining
infection in herds.infection in herds.
Pigs with mild forms of ASF may shed Pigs with mild forms of ASF may shed
virus for ~ 30 days.virus for ~ 30 days.
Bites of infected ticks.Bites of infected ticks.
African Swine Fever 2006African Swine Fever 2006
TransmissionTransmission
Once a pig is infected, the disease Once a pig is infected, the disease spreads by:spreads by:
Tom McKenna, DVM PhD, USDA APHISTom McKenna, DVM PhD, USDA APHIS, , ““African Swine FeverAfrican Swine Fever””CSU Foreign Animal Disease Training Course, Aug 1CSU Foreign Animal Disease Training Course, Aug 1--5, 2005.5, 2005.
Moritz van Vuuren, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, “African Swine Fever”
W.A. W.A. GeeringGeering, A.J. Foreman and M.J. Nunn, , A.J. Foreman and M.J. Nunn, Exotic Diseases of Exotic Diseases of AnimalsAnimals, 1995 Australian , 1995 Australian GovtGovt Publishing Service, Canberra; Publishing Service, Canberra; p.218p.218-- 224. Plus picture web sites (below pictures) 224. Plus picture web sites (below pictures)
African Swine Fever 2006African Swine Fever 2006
Image AcknowledgementsImage Acknowledgements
Watermarks key:
“CB UGA” are images provided by Dr Corrie Brown of the University of Georgia, Department of Pathology
“KAW” images were taken by Dr Kenneth A. Waldrup
“KOOS” denotes images provided by Professor Koos Coetzer of the University of Pretoria Dept of Tropical Veterinary Medicine
“LLogan” images were taken by Dr Linda Logan on her travels
“MVV” denotes those images provided by Professor Moritz van Vuuren of the University of Pretoria Dept of Tropical Veterinary Medicine
“SUZ” images were taken by Dr Suzanne Burnham
“USDA” images have mostly come from photos taken during the Plum Island FADD courses by Kathy Appicelli and Liz Clark
African Swine Fever 2006African Swine Fever 2006
AcknowledgementsAcknowledgements
Special thanks to Special thanks to
Linda Logan, DVM PhD, Linda Logan, DVM PhD, USDAUSDA
Tom McKenna, DVM USDATom McKenna, DVM USDA
Corrie Brown, DVM PhD, U of Georgia, Dept Path.Corrie Brown, DVM PhD, U of Georgia, Dept Path.