Hantavirus Pulmonary Syndrome (HPS) is one of the most rapidly progressive respiratory illnesses known to medicine. A patient who feels well enough to drive to a hospital in the morning can be on a ventilator by the afternoon. Understanding the stages of HPS — and what the warning signs look like — is critical for anyone who may have been exposed, or who is caring for someone being monitored after the MV Hondius outbreak.
After exposure to hantavirus — through inhaling aerosolized rodent excreta or, in the case of Andes virus, through close contact with an infected person — the virus can incubate silently for one to eight weeks. The average is approximately 2–4 weeks, but the wide range makes it difficult to pinpoint exposure events. During this period, the infected person feels completely well and is not known to be infectious to others.
The first symptoms of HPS are non-specific and easily mistaken for influenza or a common viral illness:
Notably absent in early HPS: cough and respiratory symptoms. This distinguishes HPS from common respiratory infections and is one reason early diagnoses are so frequently missed.
This is the most dangerous stage, and it can arrive with frightening speed — sometimes within hours of the first respiratory symptom. The immune response to the virus causes massive fluid leakage into the lungs and cardiovascular collapse:
This stage is responsible for the majority of HPS deaths. The transition from stable to critical can occur in under 24 hours. Any patient with known or suspected hantavirus exposure who develops a cough or breathing difficulty must be transferred to intensive care immediately.
Patients who survive the cardiopulmonary phase enter a recovery period during which the lungs begin to clear fluid and cardiac function improves. This phase is characterized by increased urine output as the body eliminates accumulated fluids. Recovery can be rapid — some patients are extubated within days — but others require weeks of ICU care before they can breathe independently. Long-term lung function is generally good in survivors, though fatigue can persist for months.
Hantavirus infection is confirmed by laboratory testing. The primary diagnostic tools are:
In the MV Hondius outbreak, all laboratory-confirmed cases were confirmed by PCR testing for Andes virus, with full genome sequencing performed on several isolates and published on virological.org.
There is currently no approved antiviral medication for any hantavirus infection. Ribavirin, an antiviral that showed early promise in laboratory studies, has not demonstrated clinical benefit in controlled trials for HPS. Treatment is entirely supportive, meaning doctors manage the body's systems while the immune system fights the infection:
Several patients in the MV Hondius outbreak were transferred specifically to ICU facilities in South Africa and Europe capable of providing ECMO support.