Emergence of bluetongue virus serotype 3 in the Netherlands in September 2023

Since 1998, WOAH-notifiable bluetongue virus (BTV) serotype 1, 2, 3, 4, 6, 8, 9, 11, and 16 have been reported in Europe. In mid-August, 2006, a BTV-8 outbreak started in Northwestern Europe. The Netherlands was declared BT-free again in February 2012 and annual monitoring demonstrated BT-freedom up to 2023. On September 3rd 2023, clinical manifestations in sheep typical for BT were notified to the Dutch Food and Product Safety Consumer Authority. Laboratory diagnosis confirmed BTV-infection on September 6 and the first notifications of clinical signs in cattle were also reported. Two days later, the virus was identified as serotype 3 by whole genome sequencing. Clinical signs were like these of BTV-8 outbreak and were most serious in sheep. Retrospective analysis revealed no earlier circulation of BTV. It was concluded that the BTV-3 outbreak was detected shortly after introduction, while the virus source and route of introduction remains unknown. Article summary lineDuring September 2023, a novel serotype 3 Bluetongue virus (BTV) emerged in the Netherlands which affected sheep and cattle.