What is hantavirus, the infection that has killed three people on a cruise ship? | Infectious diseases

What is hantavirus?

Orthohantaviruses, more commonly known as hantaviruses, are a group of viruses found primarily in rodents but can infect humans. According to Professor Adam Taylor of Lancaster University, there are at least 38 recognized species of hantavirus worldwide, 24 of which cause disease in humans. Rodents such as mice, rats and voles are natural reservoirs of viruses.

Dr Yomani Sarathkumara, a postdoctoral researcher at the University of Queensland, said hantavirus infections were “really rare in humans” and were often misdiagnosed in tropical countries as other infections, such as leptospirosis, which are also spread by animals.

How is the virus spread and what are the symptoms of hantavirus?

Hantaviruses are transmitted to humans through inhalation or contact with feces, urine and saliva of infected rodents – or, more rarely, through bites and scratches from contaminated animals.

“Farming communities around the world are at higher risk,” Sarathkumara said – due to a higher likelihood of exposure to infected rodents.

Associate Professor Vinod Balasubramaniam, a molecular virologist at Monash University Malaysia, said hantaviruses were “usually an environmental exposure linked to rodents” and “do not usually spread easily from person to person like the flu or Covid-19 do”.

There are two main lineages of hantaviruses: Old World hantaviruses and New World hantaviruses.

Old world hantaviruses are found in Europe and Asia, including puumala hantavirus, Hantaan virus, and Seoul virus. In humans, they usually cause hemorrhagic fever with renal syndrome (HFRS), which affects the kidneys. Symptoms may include severe headache, back and abdominal pain, fever, and potential kidney damage.

New World hantaviruses are found in the Americas and commonly cause hantavirus pulmonary syndrome. The most common type in South America is the Andes virus, which is spread primarily by the long-tailed pygmy rice rat.

“New World hantaviruses cause very rapidly progressive pulmonary syndrome and respiratory failure,” Balasubramaniam said. Initially, an infection can cause flu-like symptoms such as fever, fatigue and muscle pain, making “early diagnosis very difficult,” he said.

In March 2025, Betsy Arakawa, the wife of actor Gene Hackman, died in their Santa Fe home from hantavirus pulmonary syndrome, before her husband died of Alzheimer’s disease in the absence of her care.

Hantaviruses can have long incubation periods – between one and eight weeks, Balasubramaniam said.

According to Taylor: “A small number of studies have documented human-to-human spread of the Andean strain in South America, but a systematic review of the research did not find sufficient evidence of human-to-human transmission. »

How did the hantavirus outbreak on the cruise ship happen?

The WHO said an investigation into the suspected hantavirus outbreak on the MV Hondius was underway. Although we don’t yet know exactly how this happened, Balasubramaniam said: “There are a few biologically plausible possibilities. »

The first is the possibility of rodent contamination in the ship itself – “if infected rodents had access to storage areas…cabins and other enclosed spaces.”

The second is – because of the long incubation periods of hantaviruses – that the outbreak “would not necessarily come from the ship itself,” Balasubramaniam said. “Passengers or crew members could theoretically be exposed during land-based activities.”

The third – but least likely – is person-to-person transmission. “It’s plausible in theory, but it’s highly [unlikely]said Balasubramaniam.

“The main risk is disturbing materials contaminated by rodents…in enclosed or poorly ventilated spaces,” he said. “Risk generally does not come from simple sharing [the] same air space with an infected person.

What is the death rate from hantavirus? Is there a treatment?

Mortality rates from HFRS, caused by old world hantaviruses, are estimated to be between 1% and 15%.

“New world hantaviruses… cause much more severe symptoms and the mortality risks are much higher,” Balasubramaniam said. Hantavirus pulmonary syndrome has a mortality rate of approximately 40% in the Americas.

“We do not have a definitive antiviral [drug] it works very well,” Balasubramaniam said. Infections were usually treated with supportive management, which made early diagnosis important, he added. However, broad-spectrum antivirals are being researched for use as early treatment.

For hantavirus pulmonary syndrome, supportive care includes oxygen, fluid management, blood pressure support, and ventilation.