GENEVA, Switzerland — The World Health Organization (WHO) has confirmed that a hantavirus outbreak linked to a cruise ship has risen to 11 cases, including three deaths, as international health authorities intensify surveillance efforts amid fears that additional infections could still emerge.
In its latest update issued on May 12, WHO said nine of the reported cases have been laboratory-confirmed while two remain classified as probable infections. All cases involve passengers and crew aboard the MV Hondius, a Dutch-flagged expedition cruise vessel that has been under close international monitoring since the first reports of illness surfaced earlier this month.
“Update on #hantavirus: As of 12 May, 12h00 CEST, a total of 11 cases, including 3 deaths, have been reported. Nine of the 11 cases are confirmed, and the other 2 are probable,” WHO said.
The United Nations health agency warned that the confined conditions aboard ships, combined with hantavirus’ incubation period, could result in additional cases being identified in the coming weeks.
“We expect more cases given the dynamics of spread on a ship and the virus’ incubation period,” WHO said.
However, the organisation stressed that there is currently no indication the outbreak is escalating into a wider international public health emergency.
“At the moment, there is no sign that we are seeing the start of a larger outbreak,” WHO added.
International monitoring underway
WHO said passengers and crew members are now being monitored in their respective countries after disembarking from the vessel, with authorities recommending a 42-day follow-up period from the date of departure.
Health agencies across several countries have been advised to strengthen symptom surveillance and ensure rapid identification of suspected infections, particularly among individuals who travelled aboard the ship.
The outbreak was initially reported through the International Health Regulations (IHR) mechanism after several passengers developed severe respiratory symptoms while the vessel was sailing in the Atlantic Ocean. Earlier reports had indicated eight infections and three deaths before the case tally was revised upward in WHO’s latest assessment.
The MV Hondius, known for expedition cruises to polar and remote regions, has since become the focus of international epidemiological investigations aimed at determining the exact source and pattern of transmission.
Understanding hantavirus
Hantavirus refers to a family of viruses primarily spread by rodents such as rats and mice. Humans can become infected after inhaling airborne particles contaminated by rodent urine, saliva or droppings.
In severe cases, the infection can progress into Hantavirus Pulmonary Syndrome (HPS), a rare but potentially fatal respiratory disease characterised by breathing difficulties and fluid accumulation in the lungs.
Symptoms often begin with fever, fatigue, muscle aches and headaches before worsening rapidly in some patients.
While most hantavirus strains are not easily transmissible between humans, certain variants, including the Andes virus identified in South America, have shown limited human-to-human transmission through close contact.
WHO Director-General Tedros Adhanom Ghebreyesus earlier said the organisation was working closely with governments, international health agencies and the ship’s operators to coordinate containment efforts and support affected individuals.
He said passengers and crew are undergoing monitoring procedures in their respective countries and praised the cooperation shown during the response operation.
WHO has also emphasised the importance of balancing disease control measures with the dignity and welfare of those affected.
Kenya heightens preparedness measures
In Kenya, health authorities have moved to reassure the public that no cases have been detected locally, while simultaneously strengthening surveillance systems at points of entry following the global alert.
On May 8, the Ministry of Health confirmed that Kenya had activated precautionary preparedness measures to guard against any possible importation of the virus.
“There are currently no reported cases in Kenya. The risk to the general public remains low. Health authorities are closely monitoring the situation and taking precautionary measures,” Director-General for Health Patrick Amoth said in a statement.
According to the ministry, screening and surveillance measures have been intensified at airports, seaports and border crossings, while hospitals and health facilities have been placed on alert to identify any travellers presenting symptoms associated with hantavirus infection.
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The government has also advised the public to maintain proper hygiene practices and minimise exposure to rodents and potentially contaminated environments.
On May 9, Principal Secretary for Public Health and Professional Standards Mary Muthoni said county governments had been instructed to strengthen emergency preparedness and infection prevention systems despite the low current risk level.
“Following the reported hantavirus outbreak linked to a cruise ship abroad, counties are advised to enhance surveillance, activate emergency preparedness measures, and strengthen infection prevention and control systems,” Muthoni said.
She added that vigilance remained essential to ensure rapid detection and response should any imported case emerge.
Renewed focus on global outbreak preparedness
The outbreak has renewed global attention on infectious disease surveillance linked to international travel and confined environments such as cruise ships, which health experts say can accelerate transmission risks.
Public health analysts note that lessons learned from previous global outbreaks, including COVID-19 and mpox, have pushed governments to improve cross-border coordination, early detection systems and emergency response capacity.
Health officials are now urging travellers returning from affected cruise routes to monitor their health for up to eight weeks and seek immediate medical attention if symptoms such as fever, breathing difficulties or unexplained fatigue develop.
As investigations continue, WHO says the current focus remains on containment, early detection and international coordination while avoiding unnecessary public panic.
