Detection of a novel Shamonda Orthobunyavirus in dairy cattle, France, June 2026.

In June 2026, acute fever, diarrhoea, lethargy and marked reduction of milk yield were reported in dairy cattle in eastern France. Unbiased Nanopore metagenomics on pooled plasma from affected cows detected Simbu serogroup Orthobunyavirus, provisionally named European Shamonda Virus, and recovered complete genomes. Segments L and M clustered with Nigerian Shamonda virus, whereas S showed a distinct clustering pattern, suggesting high mutation rate or reassortment. Similar findings in neighbouring countries indicate cross-border emergence requiring coordinated surveillance.