Unusual cases of viral CNS disease Albert Rovira Veterinary Diagnostic Laboratory University of Minnesota Allen D. Leman Swine Conference 2016
Apr 15, 2017
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
• 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