Eight people infected in the hantavirus outbreak aboard the MV Hondius cruise ship have tested positive for the Andes virus, the only strain transmitted between humans, the World Health Organization says.
"Eight cases were laboratory-confirmed for Andes virus (ANDV) infection, two are probable, and one case remains inconclusive and undergoing further testing," the UN health agency said Wednesday.
Three people from the ship have died since it set sail from Ushuaia in southern Argentina on April 1 for a cruise across the Atlantic Ocean.
Two of the victims had confirmed Andes virus infections and the third is listed as a "probable" case, according to the WHO.
Hantavirus typically spreads from the urine, faeces and saliva of infected rodents. There are no vaccines or specific treatments for the rare disease.
All known cases in the current outbreak were people aboard the cruise ship.
The case listed as inconclusive is an American passenger repatriated to the United States, who is "currently asymptomatic" and undergoing further testing after one positive and one negative result, the WHO said.
It maintained its assessment of the public-health risk from the outbreak at "moderate" for those who were on the ship and "low" for the rest of the world.
The origin of the outbreak is still unknown.
The WHO says the original infection happened before the cruise, because the first victim, a 70-year-old Dutch man, started showing symptoms on April 6, while the virus' incubation period is one to six weeks.
'No indication' of mutation
The European Union's health agency ECDC said Wednesday there was nothing to suggest that the Andes strain of hantavirus had mutated following a deadly outbreak of the illness on a cruise ship.
The deaths of three passengers from the rare hantavirus outbreak has sparked international alarm. Seven others are confirmed to have the virus, including a French woman in a critical condition, while an eighth case is considered "probable," according to an AFP tally.
All of the passengers have been evacuated and are now in quarantine.
"Preliminary investigations based on the whole genome sequencing that is available to us suggest that there are no indications that this virus is acting any differently from the known virus circulating in some regions of the world," Andreas Hoefer, of the Stockholm-based European Centre for Disease Prevention and Control, told journalists.
"All sequences obtained to date are virtually identical, which means that there is likely only a single transmission event from an infected animal to a human," added Hoefer, a microbiologist and molecular epidemiologist.
The disease is usually spread from infected rodents, typically through urine, droppings and saliva.
Laboratory testing in South Africa and Switzerland confirmed the virus to be the Andes strain – the only hantavirus strain known to pass between humans.
Both ECDC and World Health Organization guidelines include a 42-day quarantine and constant monitoring of high-risk contacts because the incubation period can take six weeks.
"Due to the long incubation period, it is still possible that more cases among the passengers who are now actually in quarantine will occur," ECDC director Pamela Rendi-Wagner said.
"This cannot be excluded."
Gianfranco Spiteri, ECDC's head of global epidemic intelligence and health security, said the risk of transmission was greatest for those who showed symptoms of the illness.
But he acknowledged that people might be contagious in the first couple of days before symptoms appear.
"So in terms of taking a preventive and highly precautionary approach, we recommend for example that contact tracing should be done for two days before onset of symptoms as well," he said.
– TIMES/AFP
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