DOI: 10.2807/1560-7917.es.2026.31.42.2600883 ISSN: 1560-7917
Fatal encephalitis caused by Shamonda virus Europe 1 (SHAV-EU1) in a patient with a severely weakened immune system, France, 2026
Margot Bonnet, Hélène Labussière-Wallet, Pauline Dumez, Lucie Jauffret, Lyderic Aubert, Aurélie Avondo-Ray, Carole Seurret, Perrine Devic, Sabrine Souci, Syria Laperche, Léa Saint Martin, Emilie Frobert, Alexandre Gaymard, Jennifer Giorgi, Quentin Semanas, Richard Chalvignac, Antoine Oblette, Audrey Lapendry, Bruno Pozzetto, Thomas Perpoint, Mikail Kelleci, Aurélie Sécula, Charlotte Foret-Lucas, Clement Javaux, Florence Morfin, Antonin Bal, Elise Brottet, Catarina Krug, Frederic Jourdain, David Meyronet, Florence Ader, Jean-Luc Guérin, Laurence Josset, Grégory DestrasNew Shamonda virus clades (SHAV-EU1 and SHAV-EU2) emerged in Europe in summer 2026, primarily affecting cattle. We report the first human infection with SHAV-EU1: a French patient with a severely weakened immune system developed fatal encephalitis in September 2026, 1 month after their allogeneic stem cell transplantation. Metatranscriptomics detected SHAV-EU1 in cerebrospinal fluid, confirmed by RT-PCR. Biopsies from central nervous system showed high viral loads. Investigations revealed SHAV-EU1 in serum, respiratory and stool samples at least for 2 months before encephalitis onset.