dr. pete lasley - the dreaded ps of pork production - prrs and pedv

The Dreaded Ps of Pork Production—PRRS and PEDV

Pete Lasley DVM, MSMurphy-Brown of Missouri LLC

Outline

• PRRS & PEDV– Distribution– Virus characteristics– Clinical signs– Testing – Spread– Stability– Control and Elimination– Prevention (Biosecurity)

• Biosecurity

Porcine Reproductive and Respiratory Syndrome

(PRRS)

PRRS

• Distribution• Virus characteristics• Clinical signs• Testing • Spread• Stability• Control and Elimination• Prevention (Biosecurity)

PRRS---Characteristics

•Enveloped RNA-Virus of the family Arteriviridae •Long term viremia (~ 3 weeks)•Persistent infections (up to 157 days)•Differences in virulence •High infectivity (<10 infectious particles) but slow transmission•Short duration of immunity due to viral mutations

• Protection from one strain does not necessarily protect against another

PRRS---Characteristics

• Short colostral protection of piglets • Replicates or Multiplies in the pig‘s lungs

• porcine alveolar macrophages (PAMs)• Very sensitive virus outside of host

• Fragile to outside conditions

•Replicates in immune cells of the Lungs–porcine alveolar macrophages (PAM`s)

•Defence mechanism of the lung is impaired•Weakens nonspecific immunity

–Facilitates replication of PRRS virus

=>Increases risk of secondary infections

PRRS---Characteristics

Clinical signs in breeding herd

• Late term abortions• Stillborn, mummies and weak born piglets• Prewean mortality• Sow deaths• Decreased farrowing rate

– Pregnancy loss– Failure to conceive

Clinical signs in growing pigs

• Respiratory– Thumping in severe cases– Lack of cough in uncomplicated PRRS

• Mortality• Reduced ADG• Poorer feed conversion• Increased culls and reduced full value pigs sold

PRRS Testing

• Test for Virus– PCR– Immunohistochemistry

• Stains that show virus in tissue at a microscopic level

• Test for previous infection (exposure)– Blood testing– Oral Fluid

• ELISA, IFA

Spread

• Routes of infection– Animal contact

• New introductions to Herd

– Fomites• Objects carrying the virus

– Clothes, boots, tools, equipment

– Semen– Airborne

StabilityRelatively unstable virus

Disinfection• Susceptible to our standard disinfectants

– Reduce number not sterilize• Combination

– Clean, Disinfect, Downtime/Bake– Biosecurity

PEDV TGEV PRRS

98-100o F 3-24 hours

High temp 6-20 minutes(132o F)

Control and Elimination

• Depopulation and Repopulation– Remove all animals from herd and repopulate with clean animals

• Closures• Wait and See approach• Stimulate immunity• Tools

– Homogenize immunity• All animals exposed to the same virus

– Close the herd 210-240 days– Vaccination

• Imperfect immunity

Prevention

• Biosecurity• Biosecurity• Biosecurity

Porcine Epidemic Diarrhea Virus (PEDV)

Distribution

• 1971—Epidemic diarrhea in finishing pigs in England• 1976—Epidemic diarrhea in all age pigs in U.K.• By 1979—Many European countries had Epidemic diarrhea• During 1980’s-1990’s Virus found in Japan, Korea, & China• During 2000’s PEDV moves in other Asian countries• 2010-2012—China reports severe cases of PEDV country-wide• May 16, 2013—NVSL confirms PEDV in USA (99.4% identical

to Chinese strains).

Borrowed from Marlin and Pete Thomas Grower update

Global Perspective

Lab Submissions (PEDV positive)Blue=weekly

Red = cumulative

7-14-13 AASV-National Pork BoardLabs included; ISU ODAADDL,SDSU, & UMN

4/15/2

013

4/18/2

013

4/21/2

013

4/24/2

013

4/27/2

013

4/30/2

013

5/3/2

013

5/6/2

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5/9/2

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5/12/2

013

5/15/2

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5/18/2

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5/21/2

013

5/24/2

013

5/27/2

013

5/30/2

013

6/2/2

013

6/5/2

013

6/8/2

013

6/11/2

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6/14/2

013

6/17/2

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6/20/2

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6/23/2

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6/26/2

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6/29/2

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7/2/2

013

7/5/2

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7/8/2

013

7/11/2

013

7/14/2

0130

50

100

150

200

250

300

350

400

450

378

NPB industry meeting in Des Moines on 8.2.13:Estimates of 250,000 sows affected Loss of 1,000,000 market pigs.

How long has it been here?

• ISU fecal samples review– Dec 2012 to April 29th 2013 (index case) – Tested for PEDV

– Found only one positive on 4.16.13 in OH

• NOT circulating in growing pigs long before sow farms.

Virus Characteristics

• What is it?– Corona Virus– Other coronas

• TGE (Transmissible Gastroenteritis)

• Porcine Respiratory Corona

• Bovine Coronas• Other species

• Incubation 12-72 hours– Recent introduction– Easier tracking?

Virus Characteristics

• Route of Infection– Fecal oral route

• Not Zoonotic– Doesn’t affect people– Not a food safety

concern

Virus Characteristics

• Import/Export Issues– Not an OIE

reportable disease(World Organization of Animal Health)

– Not considered a Foreign animal Disease by USDA

Reportable Disease

Virus Characteristics

• High Replication = High shedding– 108 to 109 / gram of feces

• Scenario– Disinfectants ~99.99% effective– ~100 viral particles = disease

108 (100 M) x 0.0001 = 10,000 particles = 100 times infectious dose

Clinical Signs

• What are the Clinical Signs?– Diarrhea

• Dirty pigs

– Vomiting– Dehydration– Death

Severity of disease dependent on age

Industry Images(not our sow farms)

Sows• Gestation barn – 24-48 hrs post infection

• off feed• vomiting• scouring• abortions

• Breeding Barn – 24-48 hrs post infection• off feed• vomiting• scouring

l

Percent Survivability to Day 7

Week 1 Week 2 Week 3 Week 4 Week 5 Week 60%

20%

40%

60%

80%

100%

120%

0% 0%

25%

70%

0.95 1

Feedback initiated

• Continued Mortality 7 + days• May not wean any pigs for 3-5 weeks

Nursery-FinishNursery• High percentage of pigs effected• Mortality is low compared to

Farrowing– Can be 1-3%

Finishing• Can be missed

– Transient– ADG and F:G impact not clear

• May be more severe and ongoing if other challenges present– PRRS, PCV2, SIV

Clinical signs and impact

• This disease LOOKS much like TGEV• Almost all pigs are affected and have diarrhea

TGEV PEDV Rota virus Ileitis

Age affected All All 0-6 weeks 12+ weeks

Number affected Nearly All Nearly All Variable (5-15%) Variable (5-15%)

Clinical Signs

Diarrhea Yes Yes Yes Yes

Watery Yes Yes Less No

Vomiting Yes Yes No No

Profuse watery diarrhea and vomiting are the main clinical signs

Lesion

Necropsy -PEDV pigs(3-4 wk old)

Intestines appeared darker at first glance. Gas-filled and thin-walled. Enlarged mesenteric lymph nodes.

• Samples to submit– Small Intestines

• 4-6 areas that appear affected– Fresh and fixed tissue

– Fecal samples from affected animals

Testing

• PCR (Polymerase Chain Reaction)

– Testing of Genetic material– Genetic fingerprint

• Histology– Identification of microscopic

lesions• Serology

– Testing for immune response

Disease Spread

• Trailer and Plant study– Samples

• 669 trailers at 6 plants– Pre and post unloading

– Results• Positives

– 17% Pre (Range 2-70%)– 27% Post

– contamination at entry = at Exit

– Contamination can multiply through packing plants and transfer stations

• If cycle is unbroken (clean and disinfection)

Stability

Disinfection• Susceptible to our standard disinfectants

– Reduce number not sterilize• Combination

– Clean, Disinfect, Downtime/Bake– Biosecurity

PEDV TGEV PRRS

98-100o F 7 days 1 hour 3-24 hours

High temp 30 minutes(140o F)

6-20 minutes(132o F)

Control and Elimination

• Vaccines– No proven effective

• Some available in other countries • Work currently being done

• Medications– None effective against PEDV

• May be helpful if secondary bacterial

• Other control methods– Whole herd feedback– BIOSECURITY!– BIOSECURITY!– BIOSECURITY!

Control and Elimination

• Feedback and closure for 90-150 days– Dependent on Gilt supply

• 90 days have been effective in Asia (Geiger).

– Multiple feedback efforts• Visually inspect and mark that every sow were infected

– Vomiting– Diarrhea– Off-feed

• Be sure to re-dose anything questionable or no signs.

• Concentration of feedback varies depending who you ask.

Control and Elimination

• Why Feedback?• Why increase Disease?

– Immune Management of herd– Build Colostrum/Milk immunity

• Wean more pigs faster

– Prevent prolong continual disease in herd

Need to Know Notes

• Not a food safety/ public health concern• Very Infectious/ Hardy virus• Very Damaging to:

– Pigs pre-weaning– Productivity of Sow farm

• Biosecurity is Key

Biosecurity

Biosecurity

• What is it?– Series of Processes and Procedures to prevent or

minimize the risk of Disease.– Internal

• Barriers in place within a farm or site to prevent the spread of Disease from one group to another

– External• Minimize or prevent the entry of disease from the

outside• How we interact with the outside world

Biosecurity

• Why?– Cost of Disease

• Mortality• Loss of Productivity• Increased Labor• Increased medication• Increased vaccination• Personal and worker morale

– True value of Investment can be difficult to quantify

1. Swine diseases affect the well-being and welfare of our animals• Don’t feel well, don’t eat/drink

2. Diseases lead to a loss in animal productivity• Higher mortality• Poorer growth and feed conversion

3. Swine diseases lead to more work and medication• Pulling and treating animals• Antibiotic use increases

4. Swine disease can affect food safety and quality• More carcass contamination from animals with chronic lung lesions

Why do we need to stop diseases from moving?

Swine diseases today affect the well-being of our pigs and the success of our pigs and business.

Cost• PRRS and PEDV• It is estimated that PRRS cost the Swine industry between

$560,000,000 and $660,000,000 dollars per year– 5.7 M sows (2011 USDA)– PRRS and PEDV

• Estimates Range from $150-225 per infected sow• 5,000 head sow unit can be up to 1 Million dollars

• Cost of Biosecurity• “But I don’t have time”• “Biosecurity is too expensive”

• How much effort/ expense/time is it worth to regain 10-30% of what disease costs us?

CostPRRS PEDV

Cases Innumerable 2200+ since 4-15-13

Estimated cost/ sow ~$200($114 for every sow in US herd 42% of sow herd positive)

$165-225

Annual losses to U.S. Pork industry

$560,000,000 to $660,000,000

Yet to be Determined

Dealing with disease Control spread through BiosecurityHerd closures involving feedbackVaccination??

BiosecurityWhere are you vulnerable?

• Animal Movements • Supplies• Semen• People movements • Equipment and tools• Feed• Pests (rodents, birds, insects)• Mortality management• Land application• Maintenance

BiosecurityWhere are you vulnerable?

Animal Movements – Weaned pig trailers– Cull shipments– Replacement animals

• Status • Testing

• Questions– What routes are being taken?– Are trailers clean?– How do we interact with the driver?

• Where has he/she been?

BiosecurityWhere are you vulnerable?

• Supplies– Where are we getting them from?– Do we know that they have a no return policy?– Am I interacting with others in the process?

• Is that a risk?

– Do we enter supplies directly?– Do we clean or unpack supplies at entry?

• Semen– Do I know the boar stud procedures?– How long since last PRRS or PED break at stud?– What are their testing procedures?– Who is delivering my semen?– Who do they visit before me?– How do they interact with my farm?– How do I enter the semen?

BiosecurityWhere are you vulnerable?

People movements • Internally

– How does breeding interact with farrowing?– If finishing how do I move from barn to barn?

• Externally– Do people go outside to check feed, pumps, drains, bait, remove dead,

garbage?• What are the procedures to do that?

Equipment and tools• What comes in and out of my farm?

– Is that necessary relative to the risk?– How could I avoid that?– Do I do repairs between groups, or during?

BiosecurityWhere are you vulnerable?

• Feed• Pests (rodents, birds, insects)

– How frequently do I see mice, rats, bird, roaches, in my farm?– Do I have a good baiting program?

• Are weeds controlled around my farm?– Is Bird netting in place and in good repair?

• Mortality management– How do I remove dead?– Do I compost, render, or incinerate?

• How do I interact with rendering boxes?– Cross trafficking?

BiosecurityWhere are you vulnerable?

• Land application– Neighbors?– Who is applying?– Where have they been previously?– Were they clean coming in?

• Maintenance– Who?– When?– Where have they been?– How do they enter equipment?

Biosecurity• An Investment in:

• Health• Productivity• Financial wellbeing of operation

• Well worth a specific visit with your veterinarian

Questions?