Health chiefs are racing to trace British passengers who left thehantavirus-stricken cruise shiptwo weeks before the deadly infection was uncovered in a bid to control any further spread.
Dozens of passengers, including seven Britons, left the MVHondiusat the remote island of St Helena on 24 April, the operator Oceanwide Expeditions said, according to reports. That was nearly two weeks after the first passenger died, raising concerns that the virus could spread as travellers returned home.
Two of those passengers, who have already returned to the UK after flying back from South Africa, have been forcedto isolateat home and are currently not reporting symptoms.
But the UK Health Security Agency (UKHSA) is working to find the remaining five, as well as flight passengers, family and anyone who may have been in close contact with other passengers, to prevent it spreading further.
Professor Robin May, chief scientific officer at UKHSA, said: “We’ve been tracing individuals on the boat, contacts they have made on shore in South America who may have been associated and, of course, for the individuals who’ve returned home, earlier contacts they have made too on the flights or since they’ve been at home.
“So it’s been quite a mammoth effort. We will continue to do that if other information arises.”
There have beenthree deaths among passengers aboard the luxury cruise ship, which is currently making its way to Spain’sCanary Islands, where it will dock so passengers can disembark. Five cases have now been confirmed as hantavirus, while three others remain under investigation.
But Dr Tedros Adhanom Ghebreyesus, director-general of the World Health Organisation (WHO), warned more cases could follow.
He told reporters at a briefing on Thursday: “The WHO is aware of reports of other people with symptoms who may have had contact with one of the passengers. In each case, we are in close contact with the relevant authorities. Given the incubation period of the Andes virus, which can be up to six weeks, it’s possible that more cases may be reported.
“While this is a serious incident, WHO assesses the public health risk low.”
Hantavirus is mainly spread by contact with rodents or their urine, saliva or droppings, particularly when the material is disturbed and becomes airborne, posing a risk of inhalation. Though human-to-human transmission of the virus is rare, there is evidence that it can happen in those infected with the Andean strain suspected to be at the centre of the cruise ship cases.
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Prof May explained that UK authorities are not tracking people who may be very transient contacts, such as those who they walked past in the airport, but those who sat next to them on a flight will be alerted.
He said: “So that would be family members, people who might have shared a room on the cruise, people who may, for example, have sat directly next to somebody on a long-haul flight and reaching out to them so that they can be monitored and alerted.”
Prof May explained that “for the broader public, not directly involved in this cruise ship, the risk here is really negligible”.
But he told BBC Radio 4’sTodaythat in the “most extreme case of incubation” of hantavirus, people may have to isolate for “up to eight weeks”. However, the general consensus is that people should isolate for “probably six weeks, and so that’s the period of isolation, 45 days that we’re likely to be recommending”.
Hantavirus symptoms can start with flu-like symptoms, including a fever and muscle aches and rapidly progress into a life-threatening condition.
Symptoms hantavirus pulmonary syndrome usually show between one and eight weeks after contact with an infected rodent. As the infection progresses, patients might experience tightness in the chest as the lungs fill with fluid.
The other syndrome caused by hantavirus — hemorrhagic fever with renal syndrome — usually develops within a week or two after exposure.
People can “harbour the virus for a long time”, and some people can be asymptomatic and others may not test positive, according to Prof May.
He told BBC Breakfast: “We can test people by PCR. I’m sure people will remember during Covid, PCR tests, to look for the kind of genome of this virus in people.
“But actually that’s not always detected every time, so just because someone might have a negative test, for example, we need to continue to monitor them for some days, because the amount of the virus in people who are not displaying symptoms can be very, very low, so it can be easy to miss.
“So even for people who are healthy but have been exposed, we’ll be continuing to monitor them for quite some time when they get back to the UK.”