A woman in Germany presented with fever and severe acute kidney injury and was ultimately diagnosed with hantavirus‑associated nephritis caused by Seoul virus (SEOV). Serologic testing showed hantavirus IgG and IgM positivity, and a subsequently performed pan‑hantavirus RT‑PCR followed by sequencing of the large segment confirmed SEOV infection. Kidney biopsy demonstrated severe acute tubular injury with interstitial bleeding and strong immunohistochemical staining for hantavirus antigen in renal tubular cells.
Despite the patient owning four pet rats, none of her animals showed evidence of SEOV infection by serology or molecular testing. A joint epidemiologic investigation with local public health and veterinary authorities identified a small pet rat breeding facility as the likely source. Six rats from this facility tested positive in at least one assay, and phylogenetic analysis of partial S‑ and L‑segment sequences showed close clustering between the breeder’s rats, the patient’s virus and previously reported SEOV outbreaks in Germany and other countries. The most plausible scenario was aerosol transmission during a visit to the breeding facility several weeks before symptom onset.
This case highlights that SEOV can cause severe kidney injury requiring dialysis even without classic hemorrhagic fever signs. It also underlines that pet rat breeding facilities can act as critical reservoirs and that exposed persons may have asymptomatic infection.
The route of transmission thereby differs from the currently observed Andes Virus cluster on a cruise ship represents what is considered as rather classic: contact with rodents.
Original case report: Emerging Infectious Diseases, Vol. 31, No. 10, October 2025 – “Seoul Virus Infection, Germany, 2024”.