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Cerebral Malformations in Calves Presumed to Be Associated with an Outbreak of Bluetongue Virus Serotype 3 Infection
by
, ,
Peter Lennart Venjakob
1,*
,
Sarah Schmidt
1,
Patrick Hoch
2,
Daniela Farke
2,
Maximilien Lépine
3,
Kernt Köhler
3 and
Walter Grünberg
1 1
Clinic for Ruminants and Herd Health, Faculty of Veterinary Medicine, Justus-Liebig-University Giessen, 35392 Giessen, Germany
2
Small Animal Clinic, Justus-Liebig-University, 35392 Giessen, Germany
3
Institute of Veterinary Pathology, Justus-Liebig-University, 35392 Giessen, Germany
*
Author to whom correspondence should be addressed.
Animals 2025, 15(16), 2359; https://doi.org/10.3390/ani15162359
Submission received: 7 June 2025
/
Revised: 18 July 2025
/
Accepted: 6 August 2025
/
Published: 11 August 2025
Simple Summary
Bluetongue virus is an arthropod-borne infectious disease that affects domestic and wild ruminants. Of the more than 30 serotypes, 24 are pathogenic for ruminants and so far, 1 of them has been shown to cause cerebral malformations in offspring after transplacental infection (bluetongue virus 8). After first being identified in The Netherlands and Germany in 2023, bluetongue virus 3 was first diagnosed in Hesse, Germany, in July 2024. The present case series is a workup of 13 calves born with congenital neurologic symptoms presumably associated with transplacental fetal infection with bluetongue virus 3. Affected calves showed neurological alterations similar to lesions reported earlier in calves born from dams infected with bluetongue virus 8 during pregnancy. The examination reported here, with magnetic resonance imaging and postmortem examination, confirmed similar, severe forebrain lesions, as observed after transplacental infection with bluetongue virus 8.
Abstract
Bluetongue is a vector-borne viral infectious disease primarily affecting ruminants, transmitted by biting midges of the Culicoides species. The first bluetongue virus 3 (BTV-3) cases occurred in Hesse, Germany, in July 2024. From December 2024 onwards, field veterinarians observed calves born with neurological symptoms. A convenience sample of affected calves were admitted to the Veterinary Teaching Hospital at Justus-Liebig-University Giessen, Germany. A total of 13 calves from unvaccinated dams with pronounced neurological symptoms and positive PCR results for BTV-3 were studied. General and neurological examinations were performed and a blood sample was obtained for hematologic, blood biochemical and blood gas analysis. In 11 calves, magnetic resonance imaging (MRI) was performed. Due to the severe neurological lesions, all calves were euthanized and postmortem examinations were performed. The neurological examination of the calves revealed neurological indications consistent with diffuse forebrain disease. MRI revealed that all calves exhibited various stages of cortical parenchyma cell loss and secondary enlargement of the lateral ventricles. Postmortem examination revealed moderate to severe hydrocephalus internus or hydranencephaly. The results of clinical and neurological examinations, MRI, and postmortem examination, indicate severe impairment of brain development presumably associated with transplacental BTV-3 infection. Epidemiologic data and health records from the originating farms suggest that neurologic malformations developed after BTV-3 infection between 95 and 227 of the gestation period.
