Puumala virus is a member of the genus Orthohantavirus (family Hantaviridae) and causes a milder form of haemorrhagic fever with renal syndrome known as nephropathia epidemica. It has a tri‑segmented negative‑sense RNA genome (S, M and L) encoding the nucleocapsid protein, glycoproteins Gn and Gc and RNA‑dependent RNA polymerase. The virus was first described in 1980 after an outbreak in Puumala, Finland, and belongs to the Puumala orthohantavirus species.
Biology, Reservoir and Pathogenesis
Puumala virus is part of the Murinae‑associated clade of Old World hantaviruses. Its natural reservoir is the bank vole (Myodes glareolus), a small rodent widespread across northern and central Europe. Infection persists in voles without causing disease, and virus is shed in urine, faeces and saliva. Human infection occurs through inhalation of aerosolised rodent excreta, particularly during activities such as cleaning sheds or wood piles. Virions are enveloped and have a helical nucleocapsid. After inhalation, the virus infects endothelial cells in the kidney and vasculature, leading to increased permeability and acute kidney dysfunction. Nephropathia epidemica presents with abrupt fever, headache, back pain and sometimes blurred vision, followed by transient renal impairment. Thrombocytopenia and proteinuria are common. Mortality is low (Epidemiology and Clinical Significance
The distribution of Puumala virus mirrors that of its bank vole host, with cases reported from Scandinavia, Finland, the Baltic states, Germany, Belgium and western Russia. Epidemics tend to follow three‑ to four‑year population cycles of voles and may correlate with environmental factors such as mild winters and abundant mast crops. Finland experiences some of the highest incidences, with several thousand cases reported annually during peak years. Germany has also seen periodic surges, notably in 2010, 2012 and 2017, when large numbers of nephropathia epidemica cases were recorded. Human‑to‑human transmission has not been documented. Treatment is supportive, focusing on fluid and electrolyte management, and most patients recover fully within weeks. There is no licensed vaccine in Europe; prevention relies on reducing exposure to vole habitats through rodent‑proofing buildings and using protective equipment when cleaning areas with rodent droppings.
Puumala virus remains an important cause of renal syndrome in Europe because of its wide reservoir and the cyclical nature of bank vole populations. Although disease severity is generally mild compared with other hantavirus infections, awareness and rodent control measures can reduce infection risk. Research into vaccines and antiviral therapy continues.
Related Terms: Hantaan virus, Dobrava-Belgrade virus, Seoul virus, Sin Nombre virus, Andes virus