tanja opriessnig the roslin institute, university of edinburgh, uk veterinary diagnostic and...
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PORCINE EPIDEMIC DIARRHEA VIRUS (PEDV)
BACKGROUND AND CURRENT SITUATION IN THE USA
Tanja Opriessnig
The Roslin Institute, University of Edinburgh, UK
Veterinary Diagnostic and Production Animal Medicine
Iowa State University, USA
PRDC
PEDV Background
• Discovered in 1971 in the UK – Acute outbreaks of diarrhea in feeder pigs and fattening pigs– Suckling pigs did not become sick– Oldham et al., 1972
• Family Coronaviridae– Enveloped, positive stranded RNA viruses– Subfamilies: Coronavirinae & Torovirinae
– Important for pigs:• Genus Alphacoronavirus
– PEDV, TGEV: Diarrhea– PRCV: Respiratory disease
• Genus Betacoronavirus – Porcine haemaggluination encrophalomyelitis virus (HEV): Encephalomyelitis
• Genus Deltacoronavirus– Porcine deltacoronavirus (PDCV): Diarrhea (?)
PRDC
PEDV Background
• Structure:– Nucleocapsid (N) protein
• Highly conserved: Best for testing
– Spike (S) protein– Integral membrane (M) protein– Small envelope (E) protein
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3397359
Membrane protein M
Envelope protein E
Spike
Nucleocapsid
PRDC
PEDVAge group Diarrhea Mortality
Suckling pigs ++++100% in
naïve populations
Nursery pigs +++ ++
Grow-finish pigs ++ -
Adults + -
PRDC
PEDV PEDV Shedding
• Possible contribution factors:– Age dependency– Differences in virulence between isolates?– Cross-protection between strains?– Interaction with other pathogens?
Fecal shedding:• Up to at least 28-
35 + days post infection (neonatal and nursery pigs)
• Large amounts
Viremia:• Short (days)• Low amounts
PRDC
PEDV Global Importance
19712013
1993
1982
China:Severe epidemics in recent years
Europe:Epidemics until the late 80ies; Reports after 2000 are rare
• Only infectious for pigs– No role in public health
USA:PEDV still spreading
PRDC
PEDV USA Discovery Timeline
MON TUE WED THU FRI SAT SUN
April 15DiarrheaIA
April 16 April 17 April 18 April 19 April 20 April 21
April 22 April 23 April 24 April 25 April 26 April 27 April 28
April 29DiarrheaIA
April 30DiarrheaIA
May 1 May 2 May 3 May 4 May 5
May 6DiarrheaIA
May 7 May 8DiarrheaIN
May 9 May 10EM-CoV
May 11DiarrheaCO
May 12Pan-CoVPCR +
May 13NVSLSequencing
May 14 May 15SequencingPEDV China
May 16NVSL confirms
May 17USDA announces
May 18 May 18
Source: ISU-VDL 2013
PRDC
PEDV U.S. Pig Inventory 2007
http://www.factoryfarmmap.org/#animal:hogs;location:US;year:2007
Density Level
PRDC
PEDV June 2013
IA
INOH
MI
PA
OK
CO
SD
MN
KS
NY
IL
Introduction of PEDV into the USA TIMELINE
MO
NC
PRDC
PEDV July 2013
IA
INOH
MI
PA
OK
CO
SD
MN
KS
NY
TX
TN
WI
IL
Introduction of PEDV into the USA TIMELINE
MO
NC
PRDC
PEDV October 2013
IA
INOH
MI
PA
OK
CO
SD
MN
KS
NY
TX
TN
WI
IL
Introduction of PEDV into the USA TIMELINE
MO
NC
MD
KY
PRDC
PEDV December 2013
IA
INOH
MI
PA
OK
CO
SD
MN
KS
NY
TX
TN
WI
IL
Introduction of PEDV into the USA TIMELINE
MO
NC
MD
KY
NE
WY
CA
PRDC
PEDV January 2014
IA
INOH
MI
PA
OK
CO
SD
MN
KS
NY
TX
TN
WI
IL
Introduction of PEDV into the USA TIMELINE
MO
NC
MD
KY
NE
WY
CA
AZ SC
PRDC
PEDV February 2014
IA
INOH
MI
PA
OK
CO
ND
MN
KS
NY
TX
TN
WI
IL
Introduction of PEDV into the USA TIMELINE
MO
NC
MD
KY
NE
WY
CA
SD
MT
ID
AZSC
PRDC
PEDV March 2013
IA
INOH
MI
PA
OK
CO
SD
MN
KS
NY
TX
TN
WI
IL
Introduction of PEDV into the USA TIMELINE
MO
NC
MD
KY
MT
ID
ND
SCAZ
CA
NE
WY
MS
VT
PRDC
PEDV
Image Source: ISU-VDL 2013
Total Number of Positive Pig Samples
15-Jun-13 to 8-May-14:
Age group No.
Suckling 1,366/2,343 (49.3%)
Nursery 1,183/2,817 (36.8%)
Grow/finisher 1,199/3,123 (28.3%)
Sows/Boars 558/1,380 (28.6%)
TOTAL 4,306/9,663 (44.6%)
29 (30) States are affected to date
PRDC
PEDV
Source: Huang Y et al. mBio 2013; doi 10.1128/mBio.00737-13
2013 Genotyping
Historical PEDVs in Europe and Asia
Emerging PEDVs in Asia and the US
PRDC
PEDV Origin of the U.S. PEDV strains
Source: Huang Y et al. mBio 2013; doi 10.1128/mBio.00737-13
PRDC
PEDV Evidence of 2nd PEDV Introduction2014
Source: Wang et al. Emerging Infectious Disease 2014; No. 5, May 2014
Whole genome sequencing
Spike protein sequencing
PRDC
PEDV Diagnostics
• Diagnostic Specimens– Intestines (Fresh)– Feces– Oral fluids
– Intestines (Fixed)
– Serum
Virus isolationReal-time RT-PCR Electron microscopy
Indirect Fluorescent Antibody, ELISA
Immunohistochemistry
Sequencing
PRDC
PEDV Cumulative Number of Positive Samples
6,421
Source: AASV
16-J
un22
-Jun
28-J
un4-
Jul
10-J
ul16
-Jul
22-J
ul28
-Jul
3-A
ug9-
Aug
15-A
ug21
-Aug
27-A
ug2-
Sep
8-S
ep14
-Sep
20-S
ep26
-Sep
2-O
ct8-
Oct
14-O
ct20
-Oct
26-O
ct1-
Nov
7-N
ov13
-Nov
19-N
ov25
-Nov
1-D
ec7-
Dec
13-D
ec19
-Dec
25-D
ec31
-Dec
6-Ja
n12
-Jan
18-J
an24
-Jan
30-J
an5-
Feb
11-F
eb17
-Feb
23-F
eb1-
Mar
7-M
ar13
-Mar
19-M
ar25
-Mar
31-M
ar6-
Apr
12-A
pr18
-Apr
24-A
pr
0
1000
2000
3000
4000
5000
6000
7000
PRDC
PEDV PEDV Economic Impact
• Approximately 5 million pigs have died in the U.S.– About 4.5% of the animals sent to processing
plants last year in the U.S– Source: AgriTrends
• It is estimated 12.5 million fewer pigs will be slaughtered in 2014, which will result in an overall U.S. pork production decline of 6-7%– Largest estimated decrease in 30 years– Source: Rabobank
PRDC
PEDV Economic Impact of PEDV• Estimated shortfall in market hogs from PEDV to
North American slaughters • ((Source: Rabobank)0%
-5%
-10%
-15%
-20%
-25%
Dec 13 Mar 14 Jun 14 Sep 14 Dec 14 Mar 15 Jun 15 Sep 15 Dec 15
USCanada
Mexico
PRDC
PEDV Porcine Deltacoronavirus (PDCV)
• Initially discovered in Hong Kong in 2009 (Woo et al., 2012)
• Described in the U.S. in 2014– Associated with diarrhea in sows and
their litters– No experimental data to date– Precise pathogenesis and role of PDCV
is currently unknown
PDCV
PRDC
PEDV PEDV versus PDCV Cumulative US results
PEDV PDCV
Positive Accessions 6,421 142
Total Accessions tested 17,468 1,091
% 36.8% 13.0%
Positive States 29 (30) 14
PRDC
PEDV PEDV TransmissionWhat is known so far
• Rapidly spread across U.S.– Transport vehicles
• PEDV negative trucks returning from abattoirs positive (Lowe et al., 2014)
– Animal movement– Aerosol transmission?
Source: Dr. Darin Madson
PRDC
PEDVPEDV TransmissionRole of Feed
• Detection of PEDV RNA in feed– Confirmation of PEDV RNA in porcine plasma derived products– Relationship with PEDV outbreaks in Canada?
• Recall of pelleted nursery feeds containing plasma ingredients in Ontario
– CFIA (18-Feb-14); Feedstuffs (20-Feb-14)– 4-Mar-14: CFIA could not confirm live virus in feed pellets
containing blood plasma • Ban of spray-dried porcine plasma products in the UK (Vet
Rec, May 2014)
• Centre de développement due pork du Québec Inc (CDPQ) risk analysis
– Feed is medium risk for PEDV transmission – Study by Scott Dee, Pipestone Applied Research
PRDC
PEDV 2014 ISU Experiment
Group Designation
No. of pigs
Diet Inoculation
Dpi 0
NEG-CONTROL 8 No SDPP PBSSDPP-CONTROL 8 5% SDPP PBS
PEDV-CONTROL 8 No SDPP PEDV
Viremia only in PEDV-CONTROL groupSeroconversion only in PEDV-CONTROL group
Conclusion: No evidence of infectivity of the PEDV present in the investigated plasma lot
PRDC
PEDV Summary
• PEDV is now prevalent in the majority of swine producing states in the USA
• Epidemic situation Endemic situation?
• Lesion learned: Constant awareness– Globalization increases the risk of pathogen introductions– Need to invest in rapid epidemiological studies to
document how PEDV was introduced to the US and learn from this situation
– Need much more work on advancing understanding of transmission routes
• Pigs, people, trucks, fomites, feed, air, water etc…
STOP PEDV