What is hantavirus pulmonary syndrome (HPS)?

Hantavirus Pulmonary Syndrome (HPS) is a severe respiratory illness caused by New World hantaviruses — principally Sin Nombre virus (SNV) in North America and Andes virus (ANDV) in South America, with smaller contributions from Bayou, Black Creek Canal, Choclo and Laguna Negra viruses.

Clinical course

1. Prodrome (3–7 days): abrupt fever, severe myalgia (especially thighs and lower back), headache, fatigue, and often gastrointestinal symptoms. Easily mistaken for influenza.
2. Cardiopulmonary phase (1–7 days): dry cough, then rapidly progressive shortness of breath as fluid leaks into the lung interstitium and alveoli. Patients can deteriorate from "feeling unwell" to needing mechanical ventilation in 4–24 hours.
3. Diuretic phase: if the patient survives, fluid mobilises out of the lungs over 1–2 days, with brisk diuresis.
4. Convalescent phase: several weeks of fatigue and mild exertional dyspnoea; long-term sequelae are uncommon.

Diagnosis

Clinical suspicion in a patient with prodromal symptoms and rodent exposure; thrombocytopaenia, haemoconcentration, immunoblasts and a left shift on the blood film; chest imaging showing bilateral interstitial infiltrates; confirmatory serology (IgM/IgG) and RT-PCR.

Treatment

Aggressive supportive care: early intubation, judicious fluid management (over-resuscitation is harmful), vasopressors, and ECMO for severe cardiac and pulmonary involvement. Ribavirin is not established for HPS. Outcomes are dramatically better at centres familiar with the syndrome.

Case-fatality ratio for SNV and ANDV HPS is approximately 30–40% even with modern intensive care.