Porcine Reproductive and Respiratory Syndrome Virus
- 1. Porcine Reproductive and Respiratory Syndrome Virus(PRRSV)Katie KrimetzSeptember 4, 2008Western University of Health SciencesDVM 2010
- 2. History“Mystery Swine Disease”“Blue-eared Pig”Reproductive losses for adults, post-weaning pneumonia, suppression of growth for all agesLelystad virus coined at firsthttp://irrawaddy.org/articlefiles/8148-Pig.gif
- 3. EtiologyArteriveridae+sRNA, envelopedSpherical, 45-80nmGenus ArterivirusAlso: equine arteritis virusAntigenic differencesN. American v European55% homologousU.S. v Canadian90% homologoushttp://dantri.com.vn/Sukien/2007/4/173412.vip
- 4. PrevalenceEndemic herds (30-70% seropositive)60% of all herds have SOME seropositive pigsMorbidity/Mortality50/25% - Death usually due to bacterial infectionhttp://www.respig.com/images/prrs-weak-stillb.jpg
- 5. Risk FactorsDose/strain of virus exposed toHost SusceptibilityNursing/lacking maternal immunityYoung growing/finishing and sows lacking acquired immunityBiosecurityLarge turnoverReplacementsLack of quarantineNaïve herdSanitationhttp://www.mountairyalpacas.com/pblog/images/piglets.JPG
- 6. Transmission/SourcesConfinementDirect contact (nasal d/c, urine, feces, saliva, tonsils)Persistent InfectionIncomplete infectionVariable periods of active immunityBoarsShed for 40 days in semenReplacement giltsFomitesWorkers not a risk unless they are contaminated w/ viremic bloodAirborneRare, but possibleLow temp, low sun, high humidityDensely populatedInsects?
- 7. Immune ResponseCell-mediated immune responseVirus isolated from alveolar macrophages40% destroyed within 7 daysAntibodies are detectable by 14-21 daysSeropositive sows pass colostral antibodiesWhich decline by 3-8 weeksVirus can persist in piglets for 6-9 weeksViremia and Antibodies can exist togetherPrevents reinfection and reduces /eliminates shedding
- 8. Pathogenesis/NecropsyViremiaDistributed to bodyClinical SignsDuration: 14 daysAvid time for transplacental transmission3rd and maybe 2nd trimesterhttp://www.vetmed.iastate.edu/departments/vdpam/swine/diseases/pcv2/associated_diseases/webimages%202/lung-2.jpgFetus40-49d gestationPulmonary lesions90+d gestationUmbilical hemorrhage, necrotizing umbilical arteritis, parietal hemorrhagePigletsLungs heavy and consolidatedSevere, necrotizing, interstitial pneumoniahttp://www.hdcn.com/symp/lund/jtimg23.jpg
- 9. Clinical Signs, 2 stagesReproductive LossRespiratory DiseaseBreeding/GestationRolling anorexiaLethargyDepressionPyrexiaChronic Form (1-2 years)increased stillbirths and pre-weaning mortalityFarrowingPremature (105-107d)Increased stillbirths & mummiesAgalactic no colostrumPiglets begin “thumping”Post-weaningReduced ADG (-50-75%)PneumoniaDeath (10-25%)Respond poorly to medicationPRRSV infection without complication from opportunistic pathogens has little impact on herd health and performance
- 10. Diagnosishttp://www.ga-international.com/PCR%20LABEL.100_0879CROP.jpgPCR (serum, semen, tissue)Measures IgGs to the virusSensitive, available in short period (24-48hrs)ELISACannot differentiate antibodies from natural infection or vaccineAttempt to determine point of infection within life of pig5-7 day old piglets are great samples for detectionCatch before weaning if virus is shed during sow’s lactation
- 11. TreatmentBreeding/GestationAntibiotics for fever and reduce secondary bacterial infectionLactationAntibiotics and anti-inflammatoryDiet reformulation?Suckling pigletsAdequate environmentMortality >75% destroyElectrolytes with vitaminsPost-WeaningAntibioticshttp://www.pfizerah.com.mx/PAHimages/gs_mx_sp_images/OverviewImages/excede_3.jpghttp://www.valleyvet.com/swatches/821RX_L_vvs_000.jpg
- 12. Control and PreventionOverbreedCompensate for production lossArtificial InseminationEnsure adequate sperm cellsPostpone castration/weaningDecrease stress during loss of maternal antibodiesDip needles between injectionsAvoid hematogenous spread of PRRShttp://www.ars.usda.gov/is/graphics/photos/nov06/d630-1i.jpg
- 13. Control and PreventionDisinfectChloroform, ether, formaldehyde, phenol-based compoundsNursery DepopulationInterrupts horizontal transmissionControls opportunistic pathogens more than PRRSVaccinate (MLV)Pre-gestation sows/giltsBoarsBest for prevention against homologous reinfectionhttp://www.bi-vetmedica.com/product_sites/IngelvacPRRSATP/documents/IngelvacPRRSATP_l.jpg
- 14. http://www.cals.ncsu.edu/waste_mgt/smithfield_projects/ambient%20digester/aerialforweb.jpgBiosecurityAIAO FacilityReduces horizontal transmissionSanitationDisinfectants work well due to envelopePRRSV sensitive to pH changes <5 and >7Quarantine60-90 days minimumAcclimate new arrivalsHoused in developer facility to allow natural exposurehttp://bvaler.blogspot.com/2007_08_01_archive.html
- 15. ReferencesAPHIS. Vaccination Against Mycoplasma Pneumonia, Swine Influenza, and PRRS in Breeding Females, 2000 and 2006. In: Veterinary Services CfEaAH, ed2008.Benfield D, Calvert J, Chowdhury S, al e. Colloquium on Prospects for Development of an Effective PRRS Virus Vaccine2007; University of Illinois College of Veterinary Medicine.Cho JG, Dee SA. Porcine Reproductive and Respiratory Syndrome Virus. Theriogenoloogy. 2006;66:655-662.The Merck Veterinary Manual: Merck & Co., Inc.; 2008.RadostitsOM. Herd Health, Food Animal Production Medicine. 3rd Edition ed: W.B. Saunders Company; 2001.
- 16. Questions?