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

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, can’t 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


• 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



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

Laboratory findings



• 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

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

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