Hantavirus Doesn’t Spread Easily, but Officials May Be Downplaying Risks

Close and constant contact.

Health officials have repeatedly said this is the only way for the Andean hantavirus, which caused an outbreak on a cruise ship and captured global attention, to spread among humans.

Acting director of the Centers for Disease Control and Prevention, Dr. “You have to be in close contact with someone who has a lot of symptoms,” Jay Bhattacharya said. in an interview on Fox News.

But scientists who have been studying hantaviruses for decades are much less certain about how the virus might behave.

They agree with health officials that the Andean virus is not particularly contagious and is unlikely to cause a larger outbreak. But they said research shows that under certain conditions, the virus can be transmitted without direct contact.

“It’s important to be scientifically honest and communicate that, otherwise you lose credibility,” said Steven Bradfute, a viral immunologist and hantavirus expert at the University of New Mexico.

World Health Organization director general Dr. Tedros Ghebreyesus acknowledged in an interview that officials were emphasizing close contact as the way the virus spreads to avoid panicking people over rarer possibilities.

“It’s very difficult to explain to people who say, ‘Okay, this is an exception, this is normal,'” he said. “When you say it’s an exception, they may think this happens frequently.”

The hantavirus outbreak that started on the Dutch cruise ship MV Hondius last month has sickened at least nine people and killed three so far. Most of the approximately 150 passengers, including 18 in the United States, are being closely monitored in quarantine. What’s left is given a set of instructions To prevent spreading the virus to others: Take your temperature every day, avoid commercial flights, and try to use your own bathroom.

On Sunday’s State of the Union program on CNN, Dr. Bhattacharya was born on April 24 in St. Petersburg, an island in the Atlantic Ocean. He could not remember when some of the passengers who landed on Helena reached American soil. He said none of them showed symptoms during their travels, so authorities saw no need to warn the public or trace contacts.

“The virus does not spread unless someone has active symptoms,” he said.

This, too, is uncertain, but some scientists believe people may be most contagious when symptoms appear.

Some laboratories have been studying hantaviruses for decades, but because they grow slowly and are difficult to analyze genetically, much remains unknown about them.

Hantaviruses occur naturally in rodents. Found mainly in Argentina, where the cruise ship began its voyage, Andean virus is the only type of hantavirus known to spread among humans. But scientists have been slow to accept this possibility.

“It was very difficult to convince people of this, even here in Argentina,” said Valeria Martinez, a virologist at the National Institute of Infectious Diseases in Buenos Aires.

inside largest epidemic characterized So far, in Epuyén, Argentina, Dr. Martinez and his colleagues carefully tracked transmission patterns among 34 cases and 11 deaths between November 2018 and February 2019.

The research confirmed that the virus does not spread easily: None of the 82 healthcare workers caring for patients became infected, even though most were not wearing protective equipment.

But researchers have also identified what they call “superspreading events,” in which a single person spreads the virus to several people. The outbreak started when a man infected by rodents developed a fever and attended a birthday party with 100 guests.

Dr. “He only stayed there for 90 minutes because he felt sick,” Martinez said.

Within three weeks of the incident, five people at the party became ill. One of these five people soon died, and his wife likely passed the virus on to 10 more people after him. In total, six of the 34 cases in the outbreak had no direct contact with those who were infected, and one appears to have become infected after simply saying hello when they crossed paths.

“It’s not close contact, but it’s also not prolonged contact,” said Joseph G. Allen, director of the Healthy Buildings program at Harvard T.H. Chan School of Public Health.

Research so far suggests that the disease is most contagious when people carry a lot of the virus, perhaps when they start to feel sick. However, there are very few outbreaks large enough to be sure of this.

“We have so little data that it’s really hard to say anything concrete or definitive,” said Kartik Chandran, a virologist at the Albert Einstein College of Medicine.

Still, he and other experts said the very small number of cases should reassure people that the virus is not highly contagious. Dr. After being confined to the ship for weeks, only 11 of about 150 passengers became infected, Tedros said. “You can see that the virus is actually not as effective as Covid,” he said.

In the outbreak in Argentina, a person became ill after sharing a hospital room with a hantavirus patient, but again did not have physical contact.

Hantavirus is typically transmitted to humans when they inhale virus particles aerosolized from rodent feces. According to some experts, this fact leaves open the possibility that person-to-person transmission can also occur through the air.

“I don’t understand why we’re so reluctant to acknowledge the respiratory route when we’re talking about person-to-person transmission,” said Linsey Marr, an expert on airborne transmission of viruses at Virginia Tech.

“Airborne transmission is certainly the simplest explanation in these cases,” he said of Argentinians who had no direct contact with the patients.

Dr. from WHO Tedros said his organization did not address the findings about birthday party spread because those findings have not been replicated in other studies and the most common way the virus spreads is through close contact.

But Gustavo Palacios, a virologist at the Icahn School of Medicine at Mount Sinai and author of the paper, disagreed.

“Our paper is important because it helps define the outer limits of what the Andean virus can do under appropriate transmission conditions,” he said. “Most events will not look like this, but public health guidance still needs to account for this possibility.”

In the United States, the CDC did not issue any guidance or statement about the hantavirus outbreak until late Friday and did not hold a news conference until Saturday, nearly a month after the death of the first passenger. It still defines transmission as requiring close or intimate contact.

The CDC appears to have set an arbitrary measure of closeness, acknowledging that the threshold is “not absolute.” Yes cited Being less than 6 feet apart for more than 15 minutes is out of the Covid playbook as an indicator of risk.

Publicly, some U.S. health officials have shown uncertainty about the realities of the current epidemic. Speaking about the first two people to die from the virus in a Fox News interview, Dr. Bhattacharya incorrectly said the couple were in their 80s (ages 70 and 69) and added: “The people who were very close to them, their roommates, the doctor who cared for them, they were the ones who were symptomatic.”

He was wrong about the details. CDC scientists were not on the ship to investigate the outbreak, but WHO officials who are investigating are still trying to figure out how other passengers became infected.

The third person to die, an 80-year-old German woman, was not the roommate of the first two or even on the same deck. However, WHO’s epidemic and pandemic preparedness director, Dr. Maria Van Kerkhove said she may have shared meals with them or been in other areas.

Andrew Nixon, a spokesman for the Department of Health and Human Services, which oversees the CDC, said federal agencies were “fully engaged from the very beginning.”

The scientific basis of the one and a half meter guide or Dr. He did not respond to questions about Bhattacharya’s mistakes.

“Attempts to second-guess this response overlook the ongoing work to protect the health and well-being of American citizens,” he said.

WHO does not include 6-foot distancing in its guidance, and its statement on the outbreak acknowledges that data, including on transmission, is sparse.

Dr. “We are learning and I think we will continue to learn for a while,” Van Kerkhove said. “The book hasn’t been written.”