Swine Enteric Coronavirus Diseases
Brian J. McCluskey, DVM, MS, PhD, Dip. ACVPMChief EpidemiologistUSDA, Animal and Plant Health Inspection Service, Veterinary Services
Secreatary’s Advisory Committee on Animal HealthApril 2015
Novel Swine Enteric Coronaviruses
Porcine Epidemic Diarrhea virus (PEDv)
Porcine deltacoronavirus (PDCoV)
Picture from Wikipedia of Corona Virus
PEDv History
1969 - Large outbreaks in European swine herds Diarrhea associated with weaning or feeder pigs
▪ Suckling pigs not always affected 1976 - Affecting swine of all ages 1978 - Coronavirus-like agent was identified as
cause - Porcine Epidemic Diarrhea Virus 2010-2012 – Outbreaks of high morbidity and
mortality in China Distribution:
Asia, Canada, Columbia, Dominican Republic, Europe, United States
From: Huang et al., mBio 2013
SECD Clinical Signs Clinical signs:
Primary signs are acute watery diarrhea and vomiting▪ Acute, naïve herd: vomiting, diarrhea, loss of appetite in
all pigs. Morbidity approaches 100%▪ Suckling pigs: diarrhea, dehydration, acidosis.
▪ Mortality between 50-80+%.
▪ Feeder/Grower pigs: diarrhea, anorexia depression. ▪ Low mortality (1-3%).
▪ Endemic herd: persistent diarrhea in recently weaned pigs. Severity depends on epidemiological status of the
herd Clinical picture almost indistinguishable from TGE
SECD Differential Diagnosis
Differentials TGE (coronavirus) Rotavirus Other bacterial
diarrheal disease Parasitism
SECD Transmission
Transmission – fecal/oral route Pig to pig Fomites Vehicles Feed People
Epidemiology – Observational Study
Question topicType of Variable
Odds Ratio
p value
Interpretation
How many pelleted rations were fed to sows during the last 90 days
Continuous 0.45 0.001When the number of pelleted rations fed to sows goes up by 1, the odds of being a case goes down 55%.
Origin of sow feed used in the last 90 days
Categorical 2.33 0.002When sow feed was custom mixed off farm compared to being purchased complete, the odds of being a case goes up 2.3X.
What grain was mixed with in sow feed in the past 90 days.
Categorical 0.44 0.002
When grain was mixed with an amino acid source, salt, calcium, phosphorus and a premix in sow feed compared to only an amino acid source and a base mix, the odds of being a case goes down 56%
How many meal/mash rations were fed to nursery pigs during the last 90 days
Continuous 1.65 0.05When the number of meal/ mash rations fed to nursery pigs goes up by 1, the odds of being a case goes up 65%.
How many meal/mash rations were fed to finishers during the last 90 days
Continuous 1.51 0.004When the number of meal/ mash rations fed to finishing pigs goes up by 1, the odds of being a case goes up 51%.
Total number of rations fed to finishers during the last 90 days
Continuous 1.36 0.04When the total number of rations fed to finishing pigs goes up by 1, the odds of being a case goes up 36%.
What grain was mixed with in finisher feed in the past 90 days.
Categorical 0.50 <0.001
When grain was mixed with a supplement in finisher feed compared to with an amino acid source and a base mix, the odds of being a case goes down 50%
Contents of premix in the most recent finisher diet
Categorical 3.50 0.02When vitamin and trace mineral premix was in the same premix in the most recent finisher diet the odds of being a case goes up 3.5X.
Epidemiology – Experimental Study
Cluster, in space and time, of PEDv positive
production sites
Three different companies owned the sites
Hypothesis of airborne spread was tested by air sampling
Distance from known PEDv positive site
Number of PCR positive samples/Number of samples collected
30 ft 0/1
60 ft 3/6
300 ft 0/6
¼ mile 0/5
½ mile 1/5
1 mile 3/13
2 miles 0/4
3 miles 3/7
5 miles 0/8
10 miles 1/3
15 miles 0/4
Epidemiology – Experimental Study
A hotspot analysis (Getis-Ord Gi*) wasperformed to identify statistically significant geographic clusters of positive PEDv cases.
A neighborhood search radius of 11.5 miles was selected for this cluster analysis based on the results of the Global Moran’s I statistic.
The resulting surface shows geographic areas with significant clusters of positive sites in red and areas without significant clustering of positive sites in blue.
Epidemiology – Experimental Study
Epidemiology – System/herd investigations Investigations are being conducted on operations that are isolated geographically, have no known link to other PEDv
positive operations, experienced simultaneous clinical signs in multiple sites within a distinct system or for other
epidemiologically significant reasons.
The objectives of these investigation are: To investigate the potential pathways of introduction of the virus into the system. This objective requires completion of a standardized investigation form and in most cases a personal interview with the person most knowledgeable about the practices and procedures of the operation and a site visit. To assess the current biosecurity practices on the operation and to determine their role in the initial introduction of virus or in the spread of virus.
Investigation Results
Two investigations with feed the most likely introductory pathway (spray dried plasma implicated and feed pellets implicated)
One investigation with pig additions most likely (very small scale producer)
Three investigations with biosecurity breaches most likely (large, highly integrated systems
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Initial Response
▪ Nonregulatory▪ No mandatory reporting▪ No movement controls
▪ Epidemiological studies to investigate inter-herd transmission
▪ Epidemiological investigations and assessments to discover introductory pathways
▪ Industry and Academia led research efforts to understand viral ecology and disease dynamics
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National Animal Health Laboratory Network Accession Reporting
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Federal Order
Impact of disease called for greater Federal and State role
Required reporting allows:▪ Determination of
disease incidence▪ Improved tracking
of disease spread▪ Rapid detection of
new viruses
From: National Hog Farmer, August 2013
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Users: VS area offices
Owner: APHIS IT
Ag Connect®
ERSS, BFES, LCEM, BCOP
COGNOS®IBM Cognos®
Business Intelligence
USDA FIREWALL
Purpose: Response system to collect and manage resources, disease mitigation dataand operations activities Users: IMTs, AVIC and state animal health officials.Customer: NCAHEM
Purpose: Visualizing data and providing a common operating pictureUser: APHIS National Incident Coordinator, NAHLN Viewers: IMTs; AVICs, SAHO, IndustryOwner: IIAD
Purpose: Collecting surveillance data on a PDAUsers: Field disease diagnosticians Owner: APHIS VS IT
Purpose: Messaging lab resultsUsers: Field disease diagnosticians Owner: NVSL / NAHLN
Purpose: Query/Report ResultsUser: VS area offices
Purpose: System for sharing surveillance dataUsers: State and Fed animal health officialsOwner: APHIS VS IT
LMSLaboratory Messaging
System
EMRSEmergency Management
Response System
SCSSurveillance
Collaboration Services
MIMMobile Information
Management
Purpose: Collecting surveillance data from 3rd party providersUsers: State and VS animal health officials3rd
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Herd Management Plans
Required for herds meeting the definition of a confirmed positive
Developed with a veterinarian
Include biosecurity measures
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Funding
$26.1 million including:
$3.9 million for vaccine development
$2.4 million for laboratory testing $1.4 million for sequencing $11 million for biosecurity support
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Epidemiology
Pathways of introduction being examined:
• Intentional introduction
• Circulating in Feral swine
• Clothing/shoes contaminated on trip to China
• Human nasal passages
• Escape from laboratory or diagnostic sample
• Contaminated biological
• Antibiotic filler; e.g., rice hulls
• Pet food/treats used in swine rations
• Vitamin/mineral premixes
• Amino acid supplements
• Complete feed swine base mixes/premixes
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Information and Resources
National Pork Board Website: www.pork.org
American Association of Swine Veterinarians Website: aasv.org
USDA, APHIS, Veterinary Services Website: aphis.usda.gov
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