PRRS:UNDERSTANDING THE EPIDEMIOLOGY, VACCINATION AND OTHER STRATEGIES OF CONTROL

Dr. Wilfredo P. ResosoPresidentAccredited Swine Breeder

Association of the Philippines

OUTLINE OF THE PRESENTATION:

Introduction & Background Disease Profile Diagnostic Protocol Prevention & Control Strategy

TYPICAL PORCINE REPRODUCTIVE RESPIRATORY SYNDROME (PRRS):

Case Definition:“ A Field Update”

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

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

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

PATTERNS OF PRRSV-INFECTION

Farm Pattern Sows Weaners Grower Finishers >16wks Negative - - - - Stable + +/- - +/- Unstable Farm Sow stable/Unstable Nursery-Growers + +/- + + Acute or unstable herd + + + +

CASE DEFINITION:-TYPICALClinical Signs PRO PRRS AGAINST PRRSMorbidity rateDuration of DiseaseMortality rateConjunctivitisRhinitisRectal TemperatureFeverShort of BreathUnproductive CoughBarking CoughDyspnoeaPoor DoersConcurrent Diseases

<25% 3 weeks and longer<3% 5% 5%39*C -40*CSeldom>39.5*CSeldomSingularlySingularlySeldom>20%More Often

>50%<2 weeks>3%<1%<1%39*C – 42*C>39.5*C frequentMore frequentMore frequentMore frequentMore frequent<20% Seldom

ATYPICAL PRRS

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%

DISEASE PROFILE : SYMPTOMS Sows:

Pregnant sows recycle or abortHigh fever 41’C++Gummy eyelidNasal DischargeSkin may reddenMostly recumbent but will stand when

disturbed.Sows 2 weeks pre-farrow that aborts more

likely to die

DP- SYMPTOMS Piglets:

Huddling Febrile Conjunctivitis Leg edema, with marked discoloration Nursing piglets – 70-90% mortality Nursery/weaners – 50 – 70% mortality

DP- SYMPTOMS Growing Animals:

Respiratory Distress In-appetence “red pig” disease- reddened skin 30% mortality if complicated with other

pathogens

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.

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.

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.

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

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

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

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

YOUR THOUGHTS& COMMENTS . . .PLEASE!

International Workshop on Management and Control of Important Transboundary Diseases in the Asian Pacific Region

Thank You