Diallo BB: Jessica von Bredow-Werndl's young hopeful presumably dies of bornavirus

He was Jessica von Bredow-Werndl’s great hope for the next generation – Diallo BB. The Hanoverian, winner of the World Cup qualifier in Stuttgart and winner of the Otto Lörke Prize for the best young Grand Prix horse in Frankfurt, was eleven years old. At the weekend, the gelding was still inconspicuous and had “danced” in training, as the Olympic champion wrote on social media. Then the Dancier son’s condition deteriorated rapidly: “This illness came like a storm, silently, mercilessly and unstoppably, ate its way through your body in hours and tore my heart out of my chest. The investigations are still ongoing, and the Borna virus is suspected. No words feel big enough for what just broke inside me when we had to let you go.

Borna – 5 facts about the virus that allegedly killed Diallo

Pathogen and origin

Bornavirus (Borna Disease Virus 1, BoDV-1) is a virus that originally comes from the animal kingdom. The field shrew (Crocidura leucodon), which usually does not show any symptoms of the disease itself, is the main natural reservoir.

Disease in horses

In horses, the virus causes Borna’s disease, a severe inflammation of the central nervous system (brain and spinal cord). Typical symptoms are behavioral changes, movement disorders, paralysis and often a fatal course.

Transfer to horses

Horses presumably become infected through contact with excretions of infected shrews (e.g. saliva, urine or feces), for example via contaminated feed or bedding. The disease occurs mainly in certain endemic regions (including parts of Germany, Austria and Switzerland).

Transmission from horse to horse

According to current knowledge, direct transmission between horses is considered very unlikely or unproven. Horses are regarded as so-called “false hosts” and do not play a significant role in the spread of the virus.

Transfer to humans

Human infection with BoDV-1 is rare but possible and can lead to severe, often fatal encephalitis. Transmission is also presumably via contact with infected shrews; infection directly from horses to humans has not yet been clearly proven.

Great hope for the future: Diallo BB

Jessica von Bredow-Werndl had taken over Diallo from Uta Gräf. The pair competed at six tournaments in 2025 and recorded seven victories in international competitions. Most recently, the pair won the World Cup qualifier in Stuttgart with an 83 percent freestyle. Jessica von Bredow-Werndl wanted to build Diallo BB up slowly. He was her great hope for the future. “You were a huge gift,” wrote the Olympic champion in her emotional farewell post on Instagram.