Two distinct syndromes
Hantavirus can cause two main clinical syndromes depending on the strain involved. In Europe, Hemorrhagic Fever with Renal Syndrome (HFRS) predominates, caused mainly by the Puumala virus. Hantavirus Pulmonary Syndrome (HPS), far more severe, is primarily observed on the American continent, although cases linked to the Andes strain were documented in Europe in May 2026.
HFRS in Europe: clinical phases
HFRS caused by the Puumala virus, also known as epidemic nephropathy, progresses through several successive phases.
1. Incubation period (2 to 4 weeks)
After rodent exposure, the disease manifests on average 2 to 4 weeks later. This long asymptomatic period makes diagnosis difficult if rodent exposure is not mentioned to the doctor during the consultation.
2. Febrile phase (3 to 5 days)
Sudden and abrupt onset of:
- High fever (38.5°C to 40°C)
- Intense headaches
- Diffuse muscle pain (myalgia)
- Lower back and abdominal pain
- Visual disturbances (blurred vision, photosensitivity, halos)
- Possible nausea and vomiting
3. Oliguric phase (1 to 4 days)
Kidney involvement with significant reduction in urine output. This is the most critical phase. Hospitalisation is often necessary for monitoring and hydration. In severe cases, temporary dialysis may be required.
4. Polyuric phase
Progressive resumption of urine production, sometimes in very large quantities. Fatigue and pain may persist for several weeks.
5. Convalescence
Recovery is complete in the vast majority of cases. Permanent kidney damage is rare with the Puumala strain. Chronic fatigue is however common in the weeks following illness.
HPS: a far more severe form
HPS, caused mainly by the Sin Nombre and Andes strains, presents a very different and markedly more severe clinical picture:
- Prodromal phase (3 to 5 days): fever, intense myalgia, sometimes diarrhoea — resembles severe flu
- Cardiopulmonary phase: dry cough, progressive then sudden breathlessness, acute pulmonary oedema — deterioration can be very rapid
- Mortality rate: 30 to 50% in severe forms
When to call 112?
Call 112 (emergency) or 100 (ambulance) immediately if you experience:
- Difficulty breathing or sudden shortness of breath
- Very high fever with confusion or disorientation
- No urine for more than 12 hours
- Unexplained bleeding or bruising
- Very low blood pressure or feeling faint
Tell the emergency services that you used SymptomChecker.be and that you suspect possible rodent exposure. This information speeds up the implementation of appropriate treatment.
Diagnosis and treatment
There is no specific antiviral treatment for hantavirus in Europe. Management is symptomatic:
- Intravenous hydration and electrolyte monitoring
- Renal function monitoring
- Temporary dialysis in severe cases
Diagnosis relies on:
- IgM anti-hantavirus serology (main test)
- PCR during the acute phase
Both tests are available in all major Belgian hospitals.