Day-by-day symptom timeline (HPS)
| Phase | Days | What you may feel |
|---|---|---|
| Incubation | 1–8 weeks after exposure | No symptoms. |
| Prodromal (early) | Days 1–5 | Fever, chills, severe muscle aches in thighs/hips/back, headache, fatigue, GI upset. |
| Cardiopulmonary | Days 4–10 | Dry cough, shortness of breath, chest tightness, low blood pressure, fluid in lungs. |
| Diuretic / recovery | Days 10+ | Rapid resolution if patient survives the cardiopulmonary phase. Lung function recovers over weeks to months. |
Severity stages
Mild
Flu-like symptoms only. Manage at home, but call your doctor if you've had rodent exposure.
Moderate
Persistent high fever, severe muscle pain, mild shortness of breath. Seek same-day medical care.
Severe
Significant shortness of breath, low oxygen, low blood pressure. Hospitalization required.
Critical
Respiratory failure, shock, multi-organ involvement. ICU; ECMO may be needed.
When to call 911
Call emergency services immediately if you have any of the following after possible rodent exposure or recent travel to an outbreak area:
- Shortness of breath at rest or with mild activity
- Chest pain or pressure
- Bluish lips or fingertips
- Confusion, fainting, or unresponsiveness
- Coughing up pink, frothy fluid
- Severe abdominal or back pain with fever and reduced urination
Hantavirus vs flu vs COVID-19
| Symptom | Hantavirus (HPS) | Flu | COVID-19 |
|---|---|---|---|
| Fever | Yes, high | Yes | Common |
| Severe muscle aches | Hallmark — thighs/back | Common | Sometimes |
| Shortness of breath | Yes, sudden, late phase | Rare | Common |
| Loss of smell/taste | No | No | Sometimes |
| Sore throat / runny nose | Uncommon | Common | Common |
| GI symptoms | Common, prominent | Sometimes | Sometimes |
| Mortality (untreated/severe) | ~38% (HPS) | <0.1% | ~0.5–1% |
See the full side-by-side breakdown on Hantavirus vs COVID-19.
What hantavirus actually does inside the body
Hantavirus targets the endothelial cells lining small blood vessels. The lungs are especially vulnerable in HPS: as infected capillaries become leaky, plasma floods the alveoli (the tiny air sacs where oxygen exchange happens), producing a non-cardiogenic pulmonary edema that looks on a chest X-ray like a snowstorm. That's why oxygen levels can crash within hours after the cardiopulmonary phase begins, even in a previously healthy young adult. Recognizing this pattern early is the single biggest factor in survival.
Symptom red flags that get missed
- Severe thigh, hip, or low-back pain with fever — easy to dismiss as a pulled muscle or flu, but a classic early HPS clue.
- Profound fatigue out of proportion to other symptoms — patients often describe feeling "wiped out" before any cough begins.
- Persistent nausea, vomiting, or diarrhea with high fever — GI symptoms are common and lead many patients to think food poisoning.
- Dizziness or fainting on standing — early sign that blood pressure is dropping as capillaries leak.
- A "second wave" of feeling worse on day 4–6 after thinking you were recovering from the flu — the transition to the cardiopulmonary phase.
Symptoms in children
Children develop the same HPS phases as adults but may present more atypically: prominent abdominal pain, vomiting, and lethargy can dominate the early picture and look like appendicitis or gastroenteritis. Any child with these symptoms plus recent rodent exposure, cabin stays, or travel to an outbreak region should be evaluated promptly. See hantavirus in children for parent-focused guidance.
Symptoms in pregnancy
Pregnancy does not appear to change the incubation period, but severe HPS in the third trimester carries higher maternal mortality and a substantial risk of fetal loss. Andes virus has been associated with vertical transmission in a small number of documented cases. Pregnant patients with suspicious symptoms should be evaluated urgently and managed at a center with both ICU and high-risk obstetric capability.
What to expect during recovery
Survivors of severe HPS typically spend several days to weeks in the ICU, often requiring mechanical ventilation and, in the most severe cases, ECMO (extracorporeal membrane oxygenation). After discharge, recovery is usually steady but can take months. Common lingering issues include:
- Reduced exercise tolerance and shortness of breath on exertion for 3–6 months
- Persistent fatigue and brain fog, often improving by 6–12 months
- Mild residual changes on pulmonary function testing in some patients
- Anxiety, PTSD-type symptoms, or depression — common after any ICU stay
Long-term outcomes for HFRS (the kidney form) center more on renal recovery; most patients regain normal kidney function but a minority develop chronic kidney disease.
When to see a doctor (vs call 911)
- See your doctor within 24 hours if you have fever plus muscle aches and any history of rodent exposure, cabin stays, dusty cleanups, or recent travel to an outbreak area.
- Go to the ER same day for high persistent fever, vomiting that prevents you keeping fluids down, or any new shortness of breath.
- Call 911 for the warning signs listed above — once oxygen levels start dropping, time matters.
Andes strain — anything different?
Andes virus causes HPS and behaves clinically like other HPS strains, but it is the only hantavirus with confirmed person-to-person transmission. See Andes virus and the 2026 outbreak page for current context.
Sources
- CDC — Hantavirus signs and symptoms.
- WHO — Hantavirus disease fact sheet.
- PAHO — Andes virus clinical updates.