Re-emergence of Seoul orthohantavirus in pet rats, Germany, 2021

Seoul orthohantavirus (SEOV, family Hantaviridae), a causative agent of haemorrhagic fever with renal syndrome (HFRS) in humans, is transmitted through contact or inhalation of excreta from infected reservoir rodents (Rattus norvegicus, R. rattus and other Rattus species). SEOV has been found across the globe, in both wild and captive rats. In 2019, the first autochthonous SEOV infection was reported for a HFRS patient in Germany, originating from pet rats. Here, we describe the recent re-emergence of SEOV in two novel human disease clusters in the same region in Germany in 2021. By means of molecular investigations, we detected SEOV sequences in patient sera from both clusters. SEOV sequences were also detected in tissues of the patients’ pet rats. SEOV sequences (partial L segment) from patients and pet rats were (almost) identical to sequences from the first case, suggesting a common origin of the pet rat-associated SEOV strain for all three cases. This hypothesis will be investigated by target enrichment-based high-throughput sequencing of complete coding sequences of the viral S-, M- and L-segments from all three outbreaks. This study highlights the risks of zoonotic infections associated with the pet rat trade and the role pet rats play as reservoir hosts for SEOV. The investigations of these disease clusters fostered interdisciplinary One Health research collaboration between human and veterinary medicine.