What is the Andes virus? The hantavirus linked to a cruise ship outbreak is among the deadliest strains
The strain of hantavirus that killed three people and sickened five others on a cruise ship is the Andean strain, typically found in South America, including parts of Argentina, where the luxury cruise ship MV Hondius departed from.
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This strain, which can cause the most serious illness, is the only one known to spread from person to person.. As of Wednesday, there were eight cases; three were confirmed to be hantaviruses by laboratory testing. Three people, a married couple of Dutch nationality and another woman, died. Another person is in intensive care in South Africa.
Dr. Abraar Karan, an infectious disease physician at Stanford Medicine, said the death of the 69-year-old woman, who was on a plane just 24 hours before her death on April 26, “tells you how quickly this disease can progress.”
The investigation continues, but experts insist the cruise ship outbreak is not similar to Covid and the risk to the public is very low.
How is the Andean strain spread?
Dr. Lucille Blumberg, an infectious disease specialist at South Africa’s National Institute of Communicable Diseases, said Andean hantavirus is not easily spread through casual contact.
There are nearly 40 strains of hantavirus worldwide, and different strains cause different illnesses, according to the U.S. Centers for Disease Control and Prevention.
The virus is usually spread through contact with rodents like rats and mice. The Andean strain is mainly carried by the pygmy rice rat. Infection is usually caused by inhaling germs from airborne rodent urine, feces, or saliva.
Dr. Emily Abdoler, an infectious disease physician at University of Michigan Health, said the Andes strain is the only one capable of human-to-human transmission and, unlike other types, can spread through respiratory droplets created when a person coughs, sneezes or talks.
The virus can also be spread through bodily fluids, including the exchange of saliva and other intimate contacts.
Dr. Pablo Vial, an infectious disease doctor who studies hantavirus at the Institute of Science and Innovation in Medicine in Santiago, Chile, has treated many patients with the Andean strain. Person-to-person transmission accounts for only 2% to 5% of all virus cases in the Andes, he said.
“In previous outbreaks, there have been cases of human-to-human transmission, primarily among close contacts providing clinical care or people who have had close physical contact,” Dr. Maria Van Kerkhove, an infectious disease epidemiologist at the World Health Organization, said Wednesday.
“It’s not Covid. It’s not the flu,” she said. “It spreads very, very differently.”
But there was at least one documented “superspreader” event, in Epuyén, Argentina, in 2018, according to a report in the New England Journal of Medicine. The outbreak was sparked by three people with symptoms who attended crowded social events, including a birthday party. Ultimately, 34 cases were confirmed, with 11 deaths.
“Some people will biologically become super-spreaders,” Karan said. “In fact, they shed more virus than others. »
The virus is most transmissible to other people in the early stages of infection, before the body’s immune system begins to respond, Vial said.
The incubation period between exposure to the virus and the appearance of symptoms can vary from nine to 40 days. If there are other cases from the cruise ship, they will likely appear next week, Karan said.
Most documented cases of human-to-human transmission involve people who have had intimate contact or are in health care settings with limited protection, Blumberg said.
The risk of being a secondary case, that is, catching it from someone else, is more than 10 times higher among sexual partners than among other family members, Vial said.
“The fact that additional cases are occurring in sexual partners does not necessarily mean it is a sexually transmitted disease,” he said. “Rather, this indicates more frequent intimate contact and that the partner is usually the one caring for the infected person.”
Is there a test for hantavirus?
There are several ways to confirm a hantavirus infection.
A KLM Royal Dutch Airlines The flight attendant was hospitalized and is being tested for hantavirus after coming into contact with the Dutch woman who was on the plane shortly before her death. It is not yet known whether the flight attendant was on the same flight.
A blood test can measure levels of IgM and IgG antibodies, which tend to increase early and late during an infection. Another method is the polymerase chain reaction, or PCR, which looks for fragments of the virus’s genetic material, usually in a blood sample. PCR tests were also used early in the coronavirus pandemic and are often used to diagnose other viral illnesses. So far, some cases have been confirmed by PCR tests, according to the World Health Organization.
For high priority situations, a PCR test for viral illnesses can usually be completed within several hours.
There are still almost 150 people on board the MV Hondius. However, as the hantavirus incubation period can be up to eight weeks, it is still unclear how long passengers will need to stay on the ship.
It’s a “tricky situation,” Karan said, because many patients may be incubating the virus and not test positive.
“Let’s say you were on the ship and you were a passenger and you may have been exposed, but you’re incubating. A lot of tests won’t detect you,” Karan said. “You may not even be shedding enough virus yet for a swab to detect it. »
What makes Andes virus so deadly?
Although hantavirus infections are rare, the mortality rate can be as high as 50% because the virus tends to affect organs like the lungs and kidneys, which are essential for survival.
Vial said he has observed in his practice that the Andean strain often affects young, previously healthy men in their 30s.
Not everyone will get seriously ill. About 40% develop a mild form of the infection and 60% develop a severe form known as cardiopulmonary syndrome, which can lead to respiratory failure and cardiovascular shock. Overall, 30 to 40 percent of patients die, Vial said.
What are the symptoms of Andes virus infection?
Cases of the Andean strain may initially go unnoticed, experts say, because the virus tends to present with vague symptoms at first.
“It often starts with nonspecific symptoms, which are symptoms that people can have with many different types of infections and illnesses, such as headaches, muscle pain, abdominal pain,” Abdoler said.
These tend to occur within one to three days after symptoms appear, Karan said.
“Then it can progress to this more critical stage where you start to experience respiratory symptoms, respiratory failure and cardiac collapse,” Abdoler said. “This causes body systems essential for survival to collapse, second by second.”
Vial said some patients with the Andes strain can deteriorate within hours.
Depending on the region, the virus may present different symptoms and progress differently. In the Western Hemisphere, the virus tends to cause hantavirus pulmonary syndrome, or HPS, which can cause shortness of breath and coughing and ultimately lead to respiratory failure. The Andes strain tends to cause HPS.
“A lot of these viruses end up killing people, not only because of the infection itself, but also because of the body’s own immune response,” Karan said.
In Europe and Asia, hantavirus can cause hemorrhagic fever with renal syndrome, leading to internal bleeding and ultimately kidney failure and death.
There is no specific treatment for the virus, Abdoler said, and patients generally receive supportive care intended to combat symptoms. This could include things like medications to fight fevers or IV fluids to help with dehydration.
You can use a ventilator to make breathing easier, or even use extracorporeal membrane oxygenation (ECMO), a machine that can take over if the heart and lungs fail, Abdoler said.
Medicines called vasopressors may also be given to increase blood pressure and ensure that organs such as the brain and kidneys receive nutrients such as oxygen.
“That’s really what supportive care means, which is supporting oxygenation and supporting circulation,” Abdoler said.
