An outbreak of hantavirus on the MV Hondius cruise ship reportedly relates to the Andes strain of the virus.
Two passengers who were taken to South Africa have been confirmed to have cases of the strain, according to the country’s health minister.
Three passengers have already died, while two confirmed and five suspected cases have been identified on board.
Most have been unable to leave the ship, but three people, including a seriously ill British doctor, were evacuated in Cape Verde on Wednesday morning.
So what are the symptoms of the Andes strain of the virus, is it contagious, and how does it spread?
What is the Andes strain?
Hantaviruses, which are named after a river in South Korea, are a family of viruses mainly spread by contact with rodents or their urine, saliva or droppings.
There are more than 20 species of the disease, but the Andes strain is thought to spread by human-to-human transmission.
The strain is mostly found in Argentina and Chile - and the MV Hondius departed from Argentina around a month ago.
How does it spread?
The Andes strain is the only hantavirus strain known to spread from person to person, although it does so very rarely.
It is normally spread when people come into close contact with droppings, urine and saliva from rodents, especially in enclosed spaces with little ventilation, or when cleaning out a mouse's cage or other areas a rodent may have been.
The virus can also be caught from a bite from a rodent.
Where there is person-to-person transmission, it is through extremely close, prolonged contact with someone with symptoms.
What are the symptoms?
Hantavirus can cause two serious illnesses, the more severe of which is Hantavirus Pulmonary Syndrome (HPS).
HPS often starts with fever, aches, dizziness, and chills, before severe breathing difficulties can develop.
Dr Sonja Bartolome of UT Southwestern Medical Center in Dallas said: “Early in the illness, you really may not be able to tell the difference between hantavirus and having the flu.”
The incubation period for HPS can take between one and eight weeks for symptoms to appear.
Commonly caused by the Andes strain, HPS has a mortality rate of between 20 and 40 per cent.
The other illness, Haemorrhagic Fever with Renal syndrome (HFRS), affects the kidneys and can lead to low blood pressure, internal bleeding and acute kidney failure.
Symptoms for HFRS usually develop within a week or two after exposure. It has a lower mortality rate of between 1 and 15 per cent of patients according to the CDC.
What is the treatment?
There is no specific cure of treatment for hantavirus infections, nor any widely available vaccines.
Early medical support has been shown to increase the chance of survival, including oxygen therapy, mechanical ventilation and even dialysis, with patients treated in intensive care units.
Public health experts suggest the best way to avoid the virus is to minimise contact with rodents and their droppings.
Gloves and bleach are recommended when cleaning up rodent droppings - but not sweeping or vacuuming, which can cause the virus to get into the air.
How common is it?
According to a report from the National Institutes of Health, there are approximately 150,000 cases of HFRS worldwide each year, mostly in Europe and Asia.
More than half of the reported cases typically occur in China, while cases in the US are rare, with only 890 cases recorded between 1993 and 2023.
There was an outbreak in Argentina in 2023 which caused 34 confirmed cases with 11 deaths, which was traced back to people who had attended a party.
The virus also garnered attention in February last year when Betsy Arakawa, the wife of Oscar-winning actor Gene Hackman, died from a respiratory illness linked to hantavirus.
It is believed she contracted HPS, with nests and dead rodents found in outbuildings of her house where she was found.
