The autopsy room at the Faculty of Veterinary Medicine at ULg is renowned in Europe, especially for the large number of bovine autopsies carried out there. Owing to its reputation, the ULg Pathology Laboratory team received a great many calves with clinical signs characteristic of infection by the Schmallenberg virus. “In pathology, we study lesions in individuals after death, first on a macroscopic level and then on a microscopic level”, explains Mutien-Marie Garigliany. “We systematically took samples from many different organs such as muscles, internal organs, skin, etc. And we’re in the process of making a detailed study of the organs affected by the Schmallenberg virus”. While the lesions are most spectacular in the encephalon, infected newborns have other abnormalities such as muscular atrophy. “Discovering the organs infected by this virus will help us to understand its biology, which seems to be relatively complex”, continues the researcher.

Nine cattle out of ten infected in Belgium

Finally, Mutien-Marie Garigliany and his colleagues have also undertaken serological studies whose results will also be published in the Emerging Infectious Diseases journal (2). One study aims to analyse, on a large scale, the percentage of cows with antibodies against the Schmallenberg virus, which have therefore already been infected by it. The other aims to detect the presence of antibodies against the same virus in calves that haven’t yet ingested any colostrum.  “Colostrum is the first maternal milk every mammal drinks. Among other things, it contains antibodies from the mother. So, if calves who haven't drunk this milk have antibodies against the Schmallenberg virus, these antibodies can only result from the calf’s immune response in utero”, the researcher stresses.

As regards the first serological study, the researchers demonstrated, among other things, that 90% of adult cattle in Belgium are seropositive for the Schmallenberg virus. “We therefore know that a large majority of cattle were infected with the virus at the end of last year”, Mutien-Marie Garigliany continues. As for the serological study relating to calves, the results show, among other things, that 30% of clinically healthy calves have antibodies against the new virus before ingestion of the colostrum. “These calves have probably been infected in utero late in the gestation period and the virus was thus unable to interfere with their development”, explains the specialist.

(2) Garigliany MM, Bayrou C, Kelijnen D, Cassart D, Desmecht D. Emerging Schmallenberg virus in domestic cattle, spring 2012. Emerging Infectious Diseases, 2012, in press.