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. 2020 Nov;52(6):841-847.
doi: 10.1111/evj.13254. Epub 2020 Mar 25.

First report of equine parvovirus-hepatitis-associated Theiler's disease in Europe

Modest Vengust  1 , Mason C Jager  2 , Valentina Zalig  1   3 , Vasilij Cociancich  1 , Melissa Laverack  4 , Randall W Renshaw  4 , Edward Dubovi  4 , Joy E Tomlinson  2 , Gerlinde R Van de Walle  2 , Thomas J Divers  5
Affiliations

First report of equine parvovirus-hepatitis-associated Theiler's disease in Europe

Modest Vengust et al. Equine Vet J. 2020 Nov.

Abstract

Background: Equine parvovirus-hepatitis (EqPV-H) has been proposed as the aetiological cause of Theiler's disease, also known as serum hepatitis. EqPV-H-associated Theiler's disease has not been previously reported in Europe.

Objectives: To determine whether EqPV-H infection was associated with a 2018-2019 outbreak of Theiler's disease in four horses on a studfarm.

Study design: Descriptive case series.

Methods: The medical records of four horses from the same farm diagnosed with fatal Theiler's disease were examined retrospectively. Information collected included a clinical history, physical examination findings, tetanus antitoxin exposure, serum biochemistry and necropsy reports. Liver tissue from all four horses was tested for EqPV-H using PCR and in situ hybridisation (ISH) assays.

Results: Three of the horses had a history of recent (7-11 weeks) tetanus antitoxin administration. Liver tissue from all four horses tested positive for EqPV-H with PCR. In situ hybridisation revealed a widespread distribution of viral nucleic acid in hepatocytes in one case, and a more sporadic distribution in the remaining three cases.

Main limitations: Case controls were not available from the farm in question given the retrospective nature of analysis.

Conclusions: This case series documents the first reported EqPV-H-associated Theiler's disease in Europe and the first use of ISH to visualise the viral nucleic acid in liver tissues of horses with Theiler's disease.

Keywords: Copiparvovirus; equine parvovirus; horse; in situ hybridisation; liver; serum hepatitis.

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Conflict of interest statement

Authors’ declaration of interests

No competing interests have been declared.

Figures

Fig 1:
Fig 1:. Histological and in situ hybridisation results from Case 1 (a and b) and Case 3 (c and d).
Loss of centrilobular hepatocytes (asterisk) and an island of remnant hepatocytes (arrow), 200x, HE. Cytoplasmic vacuolation of hepatocytes (arrow), 400x, HE. Hybridisation of viral nucleic acid is highest in periportal regions and reduced in centrilobular regions where hepatocytes are lost (asterisk in inset), 200x, 1000x inset, EqPV-H in situ hybridisation. Red puncta of hybridisation within the cytoplasm of multiple hepatocytes, 600x, EqPV-H in situ hybridisation.
See this image and copyright information in PMC

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