dr. albert rovira - unusual cases of viral central nervous system disease

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  • Unusual cases of viral CNS disease

    Albert Rovira

    Veterinary Diagnostic LaboratoryUniversity of Minnesota

    Allen D. Leman Swine Conference 2016

  • Saturday (8-wk-old): lethargy and thumping. Aspirin

    Wednesday (8-wk-old): 29 pigs down, cant walk, purple extremities (HPS-like lesions on necropsy).

    Baytril

    Wednesday (10-wk-old): 0.5% CNS and 80% thumping (only moderate bronchopneumonia on necropsy).

    Baytril

    Thursday (8-wk-old): 3% mortality in 24 hrs. 1% CNS. 100% thumping/gaunt (moderate

    bronchopneumonia on necropsy). 5 pigs sent to VDL

    Thursday (finisher, same source): 80% gaunt/thumping, 2% CNS, 2% purple extremities, some swollen eyelids.

    (embolic pneumonia, pleuropneumonia, colitis on necropsy). 3 pigs sent to VDL

    Next Monday: Mortality reaches >20%

    Clinical presentation

  • Salt toxicity

    Bad Streptococcus suis

    Edema disease

    Salmonellosis

    H. parasuis

    PRRSV + secondaries

    Differential diagnosis

  • Bacteriology: S. suis (liver), P. multocida and T pyogenes (pleura and lung), E. coli (intestine) H. parasuis (brain), P. multocida and T. pyogenes (liver and lung) H. parasuis and T. pyogenes (lung)

    Laboratory findings

  • Bacteriology: S. suis (liver), P. multocida and T pyogenes (pleura and lung), E. coli (intestine) H. parasuis (brain), P. multocida and T. pyogenes (liver and lung) H. parasuis and T. pyogenes (lung)

    Histopathology: Moderate-marked non-suppurative encephalitis or meningoencephalitis (6 of 6) Marked interstitial pneumonia (8 of 8)

    Laboratory findings

  • Teschovirus

    PRRSV

    PCV2

    HEV

    Others: BVDV, EMC, PCMV, PRV, CSFV, ASFV, BlueEye, Rabies, Nipah, Japanese B, EEEV, PSV, Porcine bocavirus

    Differential diagnosis

  • Bacteriology: S. suis (liver), P. multocida and T pyogenes (pleura and lung), E. coli (intestine) H. parasuis (brain), P. multocida and T. pyogenes (liver and lung) H. parasuis and T. pyogenes (lung)

    Histopathology: Moderate-marked non-suppurative encephalitis or meningoencephalitis (6 of 6) Marked interstitial pneumonia (8 of 8)

    PCR: PRRSV POSITIVE Ct 17 - 18 (tissue homogenate) (8 of 8) Negative: PCV2, Circovirus, Pestivirus, HEV

    Laboratory findings

  • Bacteriology: S. suis (liver), P. multocida and T pyogenes (pleura and lung), E. coli (intestine) H. parasuis (brain), P. multocida and T. pyogenes (liver and lung) H. parasuis and T. pyogenes (lung)

    Histopathology: Moderate-marked non-suppurative encephalitis or meningoencephalitis (6 of 6) Marked interstitial pneumonia (8 of 8)

    PCR: PRRSV POSITIVE Ct 17 - 18 (tissue homogenate) (8 of 8) Negative: PCV2, Circovirus, Pestivirus, HEV

    VI: PRRSV POSITIVE (tissue homogenate) (8 of 8) Negative: Circovirus, Pestivirus, PRV, Enterovirus

    Laboratory findings

  • Rossow 1998: Porcine reproductive and respiratory syndrome. Vet pathol. 35:1. Other less common microscopic lesions of PRRSV infection include myocarditis,

    vasculitis, encephalitis and lymphoid hypertrophy and hyperplasia

    Rossow et al. 1999: Porcine reproductive and respiratory syndrome virus infection in neonatal pigs characterised by marked neurovirulence. Vet Rec. 144:444. Neonatal pigs from three herds of pigs were somnolent and inappetent and had

    microscopic lesions characterised by severe meningoencephalitis, necrotic interstitial pneumonia and gastric muscular inflammation

    Cao et al. 2012: Pathogenesis of nonsuppurative encephalitis caused by highly pathogenic Porcine reproductive and respiratory syndrome virus. J Vet Diagn Invest. 24:767. Since 2006, an unprecedented epidemic of highly pathogenic Porcine

    reproductive and respiratory syndrome virus (HP-PRRSV) infection has emerged and prevailed in mainland China, causing so called high fever disease with a nervous symptom that is different from typical porcine reproductive and respiratory syndrome

    PRRSV encephalitis?

  • Brain PRRSV PCR: POSITIVE Ct 16 - 21 (6 of 6)

    Brain PRRSV IHC: POSITIVE (6 of 6)

    Second opinion: Never seen anything like that

    ORF 5 sequencing: RFLP 1-8-4 95% homology with a previous virus from this system 85% homology with Chinese High Fever PRRSV

    PCR for Teschovirus: NEGATIVE at ISU (positive for Enterovirus and Sapelovirus) (1 of 1)

    Next Generation sequencing: Only PRRSV detected in brain (Minnesota VDL) Only PRRSV detected in brain (KSU VDL)

    Is PRRSV the cause of encephalitis/CNS signs?

  • Affected nurseries/finishers closed with 30-75% mortality

    PRRSV whole genome sequence: 99.9% homologous to clinically milder PRRSV from neighbor

    farm

    PRRSV experimental inoculation: CNS signs not reproduced, severe depression observed More severe clinical signs, lesions and viral load than a

    traditional 1-8-4 PRRSV strain

    Highly pathogenic 1-8-4 PRRSV causing CNS disease

  • Highly pathogenic 1-3-4 PRRSV strains

    Porcine teschovirus infections

    Viral encephalitis associated with Sapelovirus(Dr. Arruda, ISU)

    Atypical porcine pestivirus

    Other viral neurological cases reported recently

  • Previously called Porcine enterovirus serotypes 1-7 and 11-13

    Ataxia, paresis, paralysis (Teschen and Talfan disease) Less commonly nystagmus, convulsions, opisthotonus

    and coma Microscopic lesions: polioencephalomyelitis, mainly in

    spinal cord, brain stem and cerebellum Occasional cases in the US Increased frequency in the last year??

    Porcine teschovirus (PTV)

  • Previously called Porcine enterovirus serotype 8 May cause CNS signs and polioencephalomyelitis Four reports of CNS disease associated with PSV:

    Forman et al. 1982 Australia Lan et al. 2011 China Schock et al. 2014 UK Arruda et al. 2016 USA

    Recent US case: 11-wk-old pigs Ataxia, incoordination, paresis, paralysis Morbidity 20% and case fatality 30% Severe lymphoplasmacytic and necrotizing encephalomyelitis

    Increased frequency in the last year??

    Porcine sapelovirus (PSV)

  • Described in 2015 (Hause et al.)

    Apparently widespread in the US

    Two reports of association with congenital tremors: Arruda et al. 2016 USA

    Postel et al. 2016 Germany

    Recent US case associated with tremors and high mortality in 5-14-wk-old pigs (Hause et al.)

    Atypical porcine pestivirus (APPV)

  • Acknowledgements

    Dr. Stephanie RossowDr. Doug Marthaler

    Dr. Perle BoyerDr. Montse Torremorell

    Unusual cases of viral CNS diseaseClinical presentationSlide Number 3Differential diagnosisLaboratory findingsLaboratory findingsSlide Number 7Slide Number 8Slide Number 9Slide Number 10Differential diagnosisLaboratory findingsLaboratory findingsPRRSV encephalitis?Is PRRSV the cause of encephalitis/CNS signs?Slide Number 16Highly pathogenic 1-8-4 PRRSV causing CNS diseaseOther viral neurological cases reported recentlyPorcine teschovirus (PTV)Porcine sapelovirus (PSV)Atypical porcine pestivirus (APPV)Acknowledgements