What are the symptoms of hantavirus?

Initial phase (days 1-3): fever, headache, muscle pain, abdominal pain, nausea. Pulmonary phase (days 4-5): dry cough, shortness of breath, respiratory distress, pulmonary oedema. In severe cases: respiratory failure and shock.

What is the incubation period of Andes virus?

From 7 to 42 days after exposure, averaging 18 to 24 days. This is the longest range observed for any hantavirus.

How is hantavirus transmitted?

Main route: inhalation of aerosols contaminated by rodent excreta. Andes virus is the only hantavirus with documented person-to-person transmission, requiring close and prolonged contact with a symptomatic person.

What is the case-fatality rate of hantavirus pulmonary syndrome?

Between 30% and 40% depending on the strain: approximately 36% on average in the US (Sin Nombre virus), up to 40% for Andes virus.

Clinical

Symptoms and incubation

Expected clinical course, incubation period and routes of transmission of hantavirus, in particular the Andes virus responsible for the MV Hondius outbreak.

What is hantavirus?

Hantavirus is an RNA virus carried by wild rodents. In humans, it can cause two clinical forms:

Hantavirus pulmonary syndrome (HPS), affecting the lungs. The most severe form, observed mainly with American hantaviruses (including Andes virus).
Haemorrhagic fever with renal syndrome (HFRS), affecting the kidneys, observed mainly with Eurasian hantaviruses.

The Andes virus, identified in MV Hondius patients, mainly causes HPS.

Incubation period

The incubation period depends on the viral strain:

Andes virus: 7 to 42 days, on average 18 to 24 days.
Other hantavirus strains: 1 to 8 weeks.

Concretely, people exposed during the MV Hondius voyage remain monitored for at least 42 days from their last exposure. The surveillance window for the May 10, 2026 disembarkation thus ends in late June 2026.

Symptoms

Initial phase (days 1-3)

High fever and chills.
Headache.
Muscle pain (myalgia).
Abdominal pain, nausea, vomiting.

Pulmonary phase (days 4-5)

Dry cough.
Shortness of breath on exertion then at rest.
Respiratory distress.
Pulmonary oedema (fluid accumulation in the lungs).

Critical phase

In severe cases: respiratory failure, cardiogenic shock, death. The case fatality rate for HPS is estimated between 30% and 40% depending on strain and access to intensive care.

Transmission

Usual routes from rodents

Inhalation of aerosols contaminated with rodent urine, faeces or saliva.
Direct contact with fresh rodent excreta.
Rodent bite (rare).

Person-to-person transmission

The Andes virus is the only hantavirus for which person-to-person transmission has been documented. It requires close and prolonged contact with a symptomatic person, typically the same household or direct unprotected care. Airborne transmission at distance, like influenza or COVID-19, is not established. The use of personal protective equipment (FFP2/N95) during disembarkation and repatriation is a precautionary measure.