Pandemic Watch
Puumala virus vs Dobrava virus
A factual side-by-side comparison of two hantavirus strains: Puumala virus and Dobrava virus. Reservoir biology, geographic distribution, clinical course, case-fatality rate, and outbreak history.
Discovery and history
Puumala virus
Puumala virus was isolated in 1980 from bank voles trapped near the village of Puumala in southeastern Finland — the source of the name. The recognition that a hantavirus could produce a comparatively mild renal syndrome (rather than the lethal HFRS of Hantaan virus or the lethal pulmonary syndrome of Sin Nombre virus) significantly broadened the clinical spectrum understood at the time. The Finnish vernacular name for the illness, 'myyräkuume' — vole fever — reflects how thoroughly it was integrated into Northern European medicine.
Dobrava virus
Dobrava virus was first isolated in 1992 from a yellow-necked field mouse trapped near the village of Dobrava in central Slovenia. The virus had previously been suspected as the cause of severe HFRS cases reported sporadically across the Balkans, but the isolation gave researchers a defined pathogen against which to characterize the clinical syndrome and survey the rodent fauna for prevalence.
Reservoir and ecology
Puumala virus
The bank vole (Myodes glareolus, formerly Clethrionomys glareolus) is the exclusive reservoir. The species is widely distributed across the European broadleaf and mixed-forest belt from Ireland to the Urals and is one of the most abundant small mammals in its range. Bank vole populations undergo multi-year cycles tied to mast years of beech and other forest seed-bearing trees, and Puumala virus case incidence tracks those cycles with a one-year lag. The 2007 and 2010 European Puumala virus outbreak years were classic mast-driven events.
Dobrava virus
The primary reservoir is the yellow-necked field mouse (Apodemus flavicollis), a forest-dwelling rodent distributed across most of continental Europe but most abundant in the central and southeastern regions. A secondary reservoir, the striped field mouse (Apodemus agrarius), also carries Dobrava-Belgrade-virus lineages in parts of Eastern Europe. The two rodent species occupy different ecological niches (forest vs. open grassland), which produces somewhat different epidemiological patterns where they overlap.
Clinical course
Puumala virus
Puumala-virus illness is milder than other HFRS forms. Patients develop fever, myalgia, headache, abdominal pain, and visual disturbances (blurred vision is a classically described early symptom). A subset progress to acute kidney injury requiring dialysis. Hemorrhagic manifestations are typically limited to mild petechiae. Case-fatality is below 1 percent. Most patients recover fully within weeks; chronic kidney effects are uncommon but documented in a minority of severe cases.
Dobrava virus
The Dobrava-virus syndrome follows the classic HFRS five-phase course (febrile, hypotensive, oliguric, diuretic, convalescent) but with greater severity at each phase. Hemorrhagic manifestations are more pronounced than in Puumala virus disease — significant petechial rash, conjunctival hemorrhage, and gastrointestinal bleeding are common. Renal failure during the oliguric phase frequently requires dialysis. Case-fatality of up to 12 percent makes it the most lethal European hantavirus.
Notable outbreaks
Puumala virus
Puumala virus does not produce outbreaks in the cluster sense — cases are diffuse across endemic regions. What it does produce are 'epidemic years' tied to vole population peaks: 2007 across Germany and France, 2010 across Western Europe, and others. Finland sees baseline-level case counts in non-peak years and several-fold increases in peak years.
Dobrava virus
Dobrava virus cases are typically sporadic rather than clustered. The highest case densities are reported from Slovenia, Bulgaria, and Greece. Outbreak years tied to yellow-necked field mouse population cycles do occur but are less pronounced than Puumala's vole-driven epidemic years.
Prevention
Puumala virus
Aerosol exposure during cleanup of summer cottages and woodsheds after a vole-population winter is the dominant risk factor. Northern European public health agencies issue seasonal guidance encouraging wet-method cleanup, ventilation of closed structures, and N95 use when disturbing accumulated rodent debris. There is no licensed vaccine for Puumala virus specifically.
Dobrava virus
Standard rodent-exposure precautions, with the same emphasis on wet-method cleanup of accumulated rodent material in rural and forest-edge structures as for other European hantaviruses. There is no licensed Dobrava-virus vaccine.
Full strain profiles: Puumala virus · Dobrava virus. For the broader disease guide, see hantavirus.
