Where did the cruise ship hantavirus come from and what happens next?
The cruise ship hit with a deadly outbreak of hantavirus is on its way to the Canary Islands, where the remaining passengers are expected to be repatriated provided they have no symptoms. Here we look at the investigation into the outbreak and what comes next.
When did the outbreak start?
The first passengers became ill onboard the Dutch-flagged MV Hondius, a cruise ship sailing from Argentina to Cape Verde, in April, with symptoms including fever, gastrointestinal problems, pneumonia, acute respiratory distress syndrome and shock. Three people have died since 11 April, including a Dutch couple and a German woman. As of Thursday there are eight suspected cases, five confirmed as hantavirus by lab tests.
Where are those with the virus?
The body of the Dutch man who died onboard was taken off the ship at Saint Helena. He was not tested for the virus. His wife later became ill and deteriorated on a flight to Johannesburg. She died on arrival at a hospital there. Tests confirmed she had the virus. Authorities are now tracking people with whom she came into contact en route. The body of the German woman who died is still onboard. A man who presented to the ship’s doctor with symptoms was evacuated from Ascension to South Africa, where he is in intensive care but believed to be improving. He also tested positive for the virus. Another man who disembarked at Saint Helena had returned to Switzerland, but sought medical care in Zurich after developing symptoms. He has now been admitted and tested positive for hantavirus. A further three cases were evacuated to the Netherlands for treatment. One was a Dutch crew member, another a German woman who flew on to Düsseldorf. Martin Anstee, a 56-year-old retired British police officer who worked on the ship as an expedition guide, is in hospital in Leiden. On Thursday, a woman in Amsterdam, reported to be a flight attendant who came into contact with the woman who died in South Africa, came forward with potential symptoms. Two Britons who left the ship at Saint Helena in late April have returned to the UK and are self-isolating. Neither have reported any symptoms. Close contacts of those on the boat are also self-isolating.
What is hantavirus?
Hantaviruses are a large group of viruses that circulate in rodents such as mice and rats. Distinct strains are found in different parts of the world. The viruses can spread to humans, typically through inhalation of droplets or dust contaminated with urine, faeces or saliva from infected animals. In people, hantavirus infection can cause life-threatening illness. The old world strains, found in Europe and Asia, tend to cause haemorrhagic fever with renal syndrome (HFRS), a kidney disease that is fatal in about 10% of cases. The new world strains, found in the Americas, are more virulent, causing hantavirus pulmonary syndrome (HPS), which can kill more than a third of those infected.
Can it spread between people?
Most hantaviruses do not spread between people, but there have been cases of the Andes strain spreading from person to person. Lab tests have identified that strain as the cause of the outbreak on the MV Hondius. The virus is endemic to Argentina, where its host is the long-tailed pygmy rice rat. Infections are most likely through close and prolonged contact with someone in the early stages of the disease. In a previous outbreak in Argentina, in 2018-19, three people who came into contact with infected rodents spread hantavirus to 34 others, 11 of whom died.
Is any more known about the strain?
Three laboratories in South Africa, Switzerland and Senegal are working to read the whole genome of the virus. That will be compared with the genetic makeup of previous hantaviruses that have caused outbreaks, including the 2018-19 cases in Argentina. Anaïs Legand, the World Health Organization’s technical lead on viral haemorrhagic fevers, said: “It will give us a sense of whether we are seeing some changes.” Maria van Kerkhove, an infectious disease epidemiologist with the WHO, said: “From the information we have so far, and they are still doing the sequencing, we haven’t seen anything unusual, but that’s why we bring together the best minds, to be able to do that.”
Where did the virus on MV Hondius come from?
This is the big question. As part of the investigation, public health officials are compiling travel histories for all of the passengers prior to boarding, about 140 of whom are still on the ship. On Thursday, Dr Tedros Adhanom Ghebreyesus, head of the World Health Organization, said the Dutch couple, who were the first two cases, had travelled through Argentina, Chile and Uruguay on a bird-watching trip “which included visits to sites where the species of rat known to carry the virus was present”.
What happens next?
The MV Hondius is bound for the Canary Islands and is expected to arrive in Tenerife this weekend. Once docked, the 19 British nationals thought still to be onboard will be repatriated on a flight chartered by the UK Foreign Office, if they are symptom-free. All are being closely monitored. On returning to the UK they will be asked to self-isolate for 45 days, reflecting the long incubation period of hantavirus. Most symptoms develop in one to six weeks.
What is the risk to the public?
Given the long incubation period, more cases could arise among the crew, passengers and contacts of infected people who left the ship. But the UK Health Security Agency and the WHO have stressed that the risk to the wider public is low. “This is not Covid, this is not influenza; it spreads very, very differently,” said Kerkhove.
