Why symptoms are so dangerous
The main problem with hantavirus is the lack of specific early signs. The first 1–5 days of illness are almost indistinguishable from a common cold or flu. It is during this window that critical time for hospitalization is lost.
There are two main clinical forms of hantavirus infection, each with different symptoms:
- HPS (hantavirus pulmonary syndrome) — predominates in the Americas, affects the lungs, mortality 30–40%
- HFRS (hemorrhagic fever with renal syndrome) — widespread in Eurasia, affects the kidneys, mortality 1–15%
Important: The Chilean Andes virus strain is the only hantavirus reliably known to transmit from person to person. When exposed to an infected patient, the incubation period is 14–33 days — significantly longer than after inhaling rodent aerosols.
Stages of HPS — pulmonary form
HPS develops rapidly — from first symptoms to critical condition can take less than 5 days.
High fever (38–40°C), severe fatigue, muscle pain (especially thighs, back, shoulders). Possible headache, nausea, abdominal pain, diarrhea. No or minimal cough. This is where most patients think they have the flu.
Rapid increase in cough and shortness of breath. Fluid in the lungs (non‑cardiogenic edema). Drop in blood pressure, tachycardia, oxygen deprivation. Mechanical ventilation is often required at this stage. Mortality is highest.
In survivors, lung function gradually recovers. Fatigue and weakness may persist for months. Long‑term serious complications are usually absent.
Stages of HFRS — renal form
HFRS develops more slowly and has clearer staging. It is common in Russia, China, Finland, and the Balkans.
Sudden rise in temperature to 39–40°C, severe chills, headache, pain in the eyeballs when moving, lower back pain. Flushing of the face and neck, injection of the sclera (red eyes) are characteristic.
Decreased urine output (up to anuria). Worsening lower back pain. Hemorrhagic rash appears — petechiae on the skin, possible nosebleeds and gum bleeding. This is the most dangerous phase of HFRS.
Acute kidney failure. Possible complications: kidney capsule rupture, cerebral hemorrhage, septic shock. Without treatment, mortality is high.
Restoration of diuresis, normalization of temperature. Weakness and reduced urine concentration persist for several more weeks. Full recovery takes 1 to 6 months.
Comparison: hantavirus vs flu
The key diagnostic problem — in early stages, symptoms are almost identical. Here are signs that help suspect hantavirus:
| Symptom | Hantavirus | Influenza |
|---|---|---|
| Fever | 38–40°C, sudden onset | 38–39°C, gradual onset |
| Myalgia | Very severe, thighs and lower back | Moderate, generalized |
| Cough | Late onset, dry | From first days, productive |
| Abdominal pain | Common, pronounced | Rare |
| Decreased urine output | Characteristic (HFRS) | No |
| Shortness of breath | Sudden, worsening (HPS) | Moderate if complications |
| Rodent exposure history | Almost always present | No association |
| Hemorrhagic rash | Possible (HFRS) | No |
Red flags — call emergency immediately
Urgent hospitalization for any of the following symptoms:
- Shortness of breath at rest or with minimal exertion
- Respiratory rate above 25 breaths per minute
- Drop in blood pressure (systolic below 90 mm Hg)
- No urine output for more than 6 hours
- Confusion, disorientation
- Hemoptysis or bloody discharge
- Bluish lips or fingertips
- Even brief loss of consciousness
Symptoms after person‑to‑person transmission
Andes virus (Argentina, Chile) is a special case. When infected from a sick person, the symptom picture is similar to standard HPS, but there are differences:
- Longer incubation period — 14–33 days vs 1–6 weeks after rodent contact
- Possible prodromal phase with chills and sweating without prominent catarrh
- Hemorrhagic manifestations are more common than in typical HPS
- High viral load in the source — close contact (especially sexual and caregiving) increases risk
Quarantine: If Andes virus is suspected, isolation of the patient and monitoring of all contacts for 45 days from last exposure are required.
Check your symptoms right now
If you or someone close to you is experiencing any of the symptoms described above — take the risk assessment test. It takes 3–5 minutes and helps you understand whether you need to see a doctor urgently.