What is hantavirus, and why will cruise passengers spend so long in quarantine?

Original article by Donna Lu

Up to 150 people aboard the hantavirus-hit cruise ship MV Hondius began their journey home from Spain’s Canary Islands on Monday, after an outbreak that resulted in three deaths.

The World Health Organization has recommended, but not mandated, a 42-day quarantine period.

Four Australians, one permanent resident and one New Zealand citizen are expected to arrive in Australia by the end of the week, where they will spend the first three weeks of that seven-week quarantine at the Centre for National Resilience in Perth.

The facility was one of three built in response to the Covid-19 pandemic “to support the return of overseas travellers”.

Given the Covid-style quarantine of the returning passengers, how concerned should we be?

How is hantavirus spread?

Hantaviruses are usually spread to humans via through contact with or inhalation of contaminated rodent faeces, urine and saliva. Rarely, transmission can occur from a bite or scratch by infected animals.

Associate Prof Vinod Balasubramaniam, a molecular virologist at Monash University Malaysia, said hantaviruses “do not usually spread easily from person to person in the way that you see flu or Covid-19 does”.

There are two major lineages of hantavirus: old world hantaviruses and new world hantaviruses.

New world hantaviruses are found in the Americas, and usually cause hantavirus pulmonary syndrome. The most common type in South America is the Andes virus, which is also the virus responsible for the cruise ship outbreak. Unusually for hantaviruses, human-to-human spread of the Andes virus has previously been documented.

Old world hantaviruses are found in Europe and Asia – these include puumala hantavirus, Hantaan virus and Seoul virus.

The hantavirus outbreak aboard MV Hondius was “an example of inter-species disease transmission which has put health and government authorities on alert”, said Dr Ariful Islam, an epidemiologist at Charles Sturt University who specialises in biosecurity and pandemic science.

Could the hantavirus outbreak become the next Covid-19?

“This is not another Covid,” Tedros Adhanom Ghebreyesus, the director-general of the World Health Organization, said in a statement on Saturday. “The current public health risk from hantavirus remains low.”

Islam said it was important to be mindful that the next pandemic could be around the corner, but while the hantavirus outbreak was alarming, people need not panic.

“It’s not a new virus … it’s a known virus with many subtypes,” said Islam, who researches the genetic diversity of hantaviruses and their spillover risk to humans. “We know the history of host and transmission, we know the symptoms.”

It was “likely not possible” for the current outbreak “to become a full-blown pandemic similar to Covid-19 or H1N1, the previous flu pandemic”, Balasubramaniam said.  

“The concern here is not that hantavirus is going to become like Covid or influenza.” More concerning, he said, was the illness’s high mortality rate.

Fatality rates from new world hantaviruses, which cause more severe symptoms, tend to be much higher than deaths caused by the old world hantaviruses.

The new world hantaviruses cause hantavirus pulmonary syndrome, which has a fatality rate of about 40% in the Americas.

There is no specific antiviral drug to treat such viruses, which are typically managed with supportive care, including oxygen, fluid management, blood pressure support and ventilation.

Why is the quarantine period so long?

After they arrive in Australia, the passengers who were aboard MV Hondius will spend the first three weeks of a 42-day quarantine at the Centre for National Resilience in Perth.

This is due to the virus’s long incubation period – the gap between initial exposure and when symptoms first develop. “Usually when we are symptomatic, that is a clear indication of the virus successfully penetrating our immune [defences],” Balasubramaniam said

“Given the incubation of the period of the Andes virus, which can be up to six weeks, it’s possible that more cases may be reported,” Tedros said on Friday.

Interactive