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1. PRRS:
UNDERSTANDING THE
EPIDEMIOLOGY, VACCINATION AND
OTHER STRATEGIES OF CONTROL
Dr. Wilfredo P. Resoso
President
Accredited Swine Breeder Association
of the Philippines

2. OUTLINE OF THE PRESENTATION:
 Introduction & Background
 Disease Profile
 Diagnostic Protocol
 Prevention & Control Strategy

3. TYPICAL PORCINE
REPRODUCTIVE RESPIRATORY
SYNDROME (PRRS):
Case Definition:
“ A Field Update”

4. INTRODUCTION:
 Stock of the situation:
 Two genotypes:
 North American Strain (ATTC VR2332)
 Lelystad (CL2621) European strain
 Intensive interest in the syndrome
 Acute and Chronic cases
 Facts and Belief
 Simultaneous and Previous Infection
 Density of Population

5. BACKGROUNDER:
 Serological survey on the prevalence of PRRS virus among
swine producing farms in the Philippines.
 Third quarter 1995 (2,891 serum samples collected & tested)
 1,415 = 48.94 % 12 regions
 Serological Testing and Developing Herd Profiles for the
Effective Control of PRRS.
 The symptomatic approach in controlling PRRS provided
more answers.
 Variability do exists.
 Skills in differential diagnosis is critical.
 Epidemiological understanding of PRRS is important.
 These are the first set of tools to control PRRS and the
other set of tools are proper management and vaccination

6. PRRSV TRANSMISSION
 83% Lateral: Biosecurity(70% in winter)
 17% Infected semen or pigs
 Direct contact & Semen (Intermittenshedding)
 Clothing & Footwear
 Needle & Mosquitoes (Aedes vexans)
 Flies (>1.7 km)
 Contaminated trailers with PRRSV or PRRSV-infected pigs (Dee et
al.)
 - Ok when cleaning & drying or using disinfectants

7. PATTERNS OF PRRSV-INFECTION
 Farm Pattern Sows Weaners Grower Finishers
>16wks
 Negative - - - -
 Stable + +/- - +/-
 Unstable Farm
 Sow stable/Unstable
Nursery-Growers + +/- + +
 Acute or unstable herd + + + +

8. CASE DEFINITION:-TYPICAL
Clinical Signs PRO PRRS AGAINST PRRS
Morbidity rate
Duration of Disease
Mortality rate
Conjunctivitis
Rhinitis
Rectal Temperature
Fever
Short of Breath
Unproductive Cough
Barking Cough
Dyspnoea
Poor Doers
Concurrent
Diseases
<25%
3 weeks and longer
<3%
5%
5%
39*C -40*C
Seldom>39.5*C
Seldom
Singularly
Singularly
Seldom
>20%
More Often
>50%
<2 weeks
>3%
<1%
<1%
39*C – 42*C
>39.5*C frequent
More frequent
More frequent
More frequent
More frequent
<20%
Seldom

9. ATYPICAL PRRS

10. DISEASE PROFILE-ATYPICAL
 Highly Contagious, viral disease caused by
Arterivirus
 Started in June 2007 in Bulacan Backyard farms
and spread northwards up to Isabela and
southwards up in Batangas
 Only in Luzon –confirmed cases of HP-PRRS.
 Starts mostly in sows and affect all age groups.
 No parity predisposition.
 Mortality observed in all stages but more lethal in
piglets
 Abortion is high up to 5-8%

11. DISEASE PROFILE : SYMPTOMS
 Sows:
 Pregnant sows recycle or abort
 High fever 41’C++
 Gummy eyelid
 Nasal Discharge
 Skin may redden
 Mostly recumbent but will stand when disturbed.
 Sows 2 weeks pre-farrow that aborts more likely
to die

12. DP- SYMPTOMS
 Piglets:
 Huddling
 Febrile
 Conjunctivitis
 Leg edema, with marked discoloration
 Nursing piglets – 70-90% mortality
 Nursery/weaners – 50 – 70% mortality

13. DP- SYMPTOMS
 Growing Animals:
 Respiratory Distress
 In-appetence
 “red pig” disease- reddened skin
 30% mortality if complicated with other pathogens

14. LESIONS:
 Lymph nodes are enlarged and hemorrhagic.
 Spleen with infarct
 Kidneys hemorrhagic ranging from petechial to
ecchymotic
 Lungs grossly hemorrhagic
 Tonsils no lesions
 Most of the lesons similar to that observed in CSF
cases.

15. FIELD OBSERVATIONS
 Antibiotic – slow or not effective
 High Fever 41’C++
 Antipyretic alleviates fever but it may recur in the
following days.
 Long resolution, production failure may last 4-6
months depending on complications.
 Farms below 1,000 sows go back to normalcy on a
shorter time period.
 MADEC 20 points program chops off mortality
percentage.
 Respiratory problems occur at the same time or
may follow the reproductive problem.
 Mode of transmission – animals, vectors and
fomites.

16. FIELD OBSERVATIONS 2:
 Farms affected may suffer from other infections like
PED, HC, PCVAD, Exudative Epidermatitis, Ileitis.
 Infection in 85% of the cases is initiated in pregnant
animals and its spread to other production stages in
single site farms.
 Causative organisms are immunosuppressant.

33. RECOMMENDED VACCINATION PROGRAM
 Naivë Herd (Negative Herd)
 Gilts and young boars
 2 vaccinations (with a killed PRRS vaccine) before breeding,
at least 3 weeks interval between vaccination and the second
dose should be at least 3 weeks prior to breeding
 Sows
 Mass vaccination every 4 months (3 times per year) using a
killed PRRS vaccine or,
 one dose 3-4 weeks before farrowing (killed vaccine)
 Piglets
 No vaccination
 Boars
 2 – 3 vaccinations per year with a killed PRRS vaccine

34.  Positive – stable farms
 Gilts and young boars
 2 vaccinations (with a MLV PRRS vaccine) before breeding, at least 3 weeks
interval between vaccinations and the second dose should be at least 3 weeks
prior to breeding
 Sows
 Initial Program
 2 Mass vaccinations with 4 weeks interval
 Maintenance program (4 options)
 One mass vaccination every 4 months with a Killed PRRS vaccine
 One regular vaccination with a Killed PRRS vaccine 3 -4 weeks before
farrowing
 One mass vaccination every 4 months with a MLV PRRS vaccine
 One regular vaccination with a MLV PRRS vaccine 12-15 days after each
farrowing
 Piglets
 simultaneous with the first mass vaccination in sows, piglets aged 18 – 30 days
can be vaccinated (MLV vaccine) or mass vaccination of pigets (day 1 – 70 days)
 thereafter, regular program 21 – 28 days of age (14 – 28 days old)
 Boars
 2 – 3 times per year with a MLV PRRS vaccine

35.  Positive – Unstable farms
 Gilts and young boars
 2 vaccinations (with a MLV PRRS vaccine) before breeding, at least 3
weeks interval between vaccinations and the second dose should be at least
3 weeks prior to breeding
 Sows
 Initial Program
 2 Mass vaccinations with 4 weeks interval
 Maintenance program (4 options)
 One mass vaccination every 4 months with a Killed PRRS vaccine
 One regular vaccination with a Killed PRRS vaccine 3 -4 weeks before
farrowing
 One mass vaccination every 4 months with a MLV PRRS vaccine
 One regular vaccination with a MLV PRRS vaccine 12-15 days after
each farrowing
 Piglets
 simultaneous with the second mass vaccination in sows, piglets aged 18 –
30 days can be vaccinated (MLV vaccine) or mass vaccination of piglets
(day 1 – 70 days)
 thereafter, regular program 21 – 28 days of age or (14 – 28 days)
 Boars
 2 – 3 times per year with a MLV PRRS vaccine

37. SUMMARY/RECOMMENDATIONS:
 VACCINATION IS REQUIRED
 CLOSE HERD PROGRAM
 STRICT BIOSECURITY PROGRAM IMPLEMENTED.
 STRATEGIC MEDICATION FOR BACTERIAL INFECTION.
 BEST MANAGEMENT PRACTICES
 SEGREGATED EARLY WEANING
 DEPOPULATION
 FEED ADDITIVES REDUCES VIRUS PRESSURE
 ALL IN ALL OUT
 MULTISITE SYSTEM
 STRICT CULLING

38. YOUR THOUGHTS
& COMMENTS . . .
PLEASE!
International Workshop on
Management and Control of
Important Transboundary
Diseases in the Asian
Pacific Region

39. Thank You