Diagnosis — Hantavirus
Why hantavirus diagnosis is difficult
Hantavirus infection is notoriously difficult to diagnose in its early stages. The prodromal symptoms — fever, fatigue, myalgia, headache, and gastrointestinal complaints — are indistinguishable from influenza, COVID-19, leptospirosis, rickettsial diseases, and early bacterial sepsis.
The critical clinical clue is rodent exposure history in the preceding 1–8 weeks. Healthcare providers in endemic areas should maintain a high index of suspicion and ask patients about:
- Recent cleaning of rodent-infested buildings (barns, cabins, sheds)
- Exposure to rural or wilderness areas
- Known hantavirus cases in the community
- Occupational exposure (farmers, forestry workers, pest control)
Laboratory confirmation
| Test | Timing | What it detects | Notes |
|---|---|---|---|
| IgM ELISA | Day 1–3 of symptoms | Anti-hantavirus IgM antibodies | Most common screening test; confirmatory |
| IgG ELISA | Day 7+ | Anti-hantavirus IgG antibodies | Indicates past or resolving infection |
| RT-PCR | Acute phase (early) | Viral RNA in blood or tissue | Highly specific; strain identification possible |
| Immunohistochemistry (IHC) | Post-mortem or biopsy | Viral antigen in tissue | Gold standard for fatal cases |
| Focus reduction neutralisation test (FRNT) | Convalescent | Neutralising antibodies (strain-specific) | Reference standard; not widely available |
Supporting clinical findings
- Thrombocytopenia (low platelets) — found in virtually all HPS patients
- Leukocytosis with left shift (elevated white blood cells)
- Hemoconcentration (elevated haematocrit)
- Elevated LDH and AST
- Proteinuria (protein in urine) — especially in HFRS
- Bilateral pulmonary infiltrates on chest X-ray (HPS)
When to suspect hantavirus
The CDC recommends considering hantavirus testing when a patient presents with:
- Fever AND
- Pulmonary infiltrates (HPS) or acute kidney injury (HFRS) AND
- History of potential rodent exposure in the Americas or Eurasia
Sources
- CDC. Diagnosing HPS. CDC Diagnosis
- Knust B, Rollin PE. Twenty-year summary of surveillance for human hantavirus infections, United States. Emerg Infect Dis 2013;19(12):1934-1937.
- Hjelle B, Torres-Pérez F. Hantaviruses in the Americas. Antiviral Res 2010.