Where is it, what should you know

An outbreak of hantavirus on a ship has outraged the public and renewed fears of another global health threat as passengers are scattered across many countries, including the US.

The World Health Organization has reported 11 cases linked to the outbreak since Tuesday, nine of which have been confirmed, including three deaths. No Americans have tested positive for HIV as of Wednesday.

Other passengers are being monitored at specialized medical facilities, including 18 in the US across Nebraska and Atlanta. A number of people not connected to the cruise are being screened for exposure to many states. Targeted treatment for hantavirus is years away: Shares of Modern rallied nearly 12% on Friday after it confirmed it was conducting early research on a potential vaccine to protect against hantavirus.

But as the number of people exposed and public concern grows, health experts aim to allay fears of another pandemic. Their message: This is not Covid-19 anymore.

Unlike Covid, measles or influenza, the specific Andes strain of hantavirus in the outbreak does not spread easily between people, making the risk of spillover spread in the community low. More cases could emerge in the coming weeks because hantavirus has a long incubation period, experts say.

However, “we don’t expect a large number of infections and they will probably remain limited to passengers exposed on board, especially since we already have containment measures in place,” said Dr. Nicole Iovine, a hospital epidemiologist and infectious disease physician at the University of Florida, in an interview.

But for some experts, the outbreak raises broader concerns about how the US is equipped to respond to future infectious disease threats, especially after major cuts to the Centers for Disease Control and Prevention and the Trump administration’s move to withdraw from the WHO last year.

While experts say the CDC appears to have the hantavirus outbreak under control, others warn that the situation exposes cracks in the country’s public health infrastructure that could have far-reaching consequences in the face of the highly infectious pathogen.

“I don’t expect any significant risk to American society. But if this is a stress test, we’ve failed this,” said Lawrence Gostin, professor of public health law at Georgetown University. “Just imagine if this was a highly contagious agent.”

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Here’s what you need to know about where the hantavirus outbreak stands, and what it says about the US’s ability to contain infectious diseases.

The risk of this hantavirus to the general public remains low, according to WHO public health experts. That’s because hantavirus doesn’t spread as easily as other viruses like Covid.

Hantavirus is mainly spread to humans through contact with infected wild rodents, particularly by inhaling airborne particles from urine, feces, or saliva. Cases of hantavirus disease are rare in the US: From 1993 to 2023, 890 cases were reported, most of them in Western countries, CDC data shows.

The Andes virus seen in this outbreak – and found in South America – is the only hantavirus that can spread from person to person. However, there are few cases of human-to-human transmission, so the medical community gets clues from previous outbreaks.

The Andes strain is often spread by “close and frequent contact” with an infected person who shows symptoms, said Dr. Kari Debbink of the Johns Hopkins Bloomberg School of Public Health.

Debbink said that’s not like Covid, which “spreads well without prolonged exposure.” Hantavirus is not considered airborne because it does not remain in the air to infect others in the same way as respiratory viruses such as Covid, influenza and measles.

But cruise ships like the MV Hondius are considered hotbeds of disease transmission because they bring together a wide variety of people and stick them in close quarters for days or weeks.

“Cruise ships are one of the most dangerous things for public health. They are floating petri dishes that are isolated in the water,” said Dr. Tyler Evans, CEO of the public health organization Wellness Equity Alliance and former New York City medical officer responsible for Covid.

WHO investigators believe the outbreak originated from a Dutch couple on board the MV Hondius who later died of their illnesses.

Before they boarded, the couple had gone on a bird-watching trip to Argentina, Chile and Uruguay, Dr. Tedros Adhanom Ghebreyesus, director-general of the WHO, speaking at a briefing on May 7. He said the couple’s bird-watching trip included visiting areas where “a type of rat known to carry hantavirus was present,” he said.

Hantavirus has an incubation period of one to six weeks after exposure, which means more cases will emerge, Debbink said. But people who come into contact with infected people are considered symptomatic in special institutions, so “this must be contained immediately,” he added.

The US is likely to have an outbreak under control given the hantavirus strain. But some health experts have raised concerns about the lack of a strong response from the CDC under Trump, and raised broader fears about whether the US is prepared for future, infectious global health threats.

“CDC has always been at the forefront of health emergencies around the world — from SARS-CoV-2 to Ebola to Zika,” said Georgetown’s Gostin. “And because of this, the CDC is ineffective. Their response is disjointed and too late.”

For decades, the CDC has built a reputation as the world’s leading public health agency, quickly coordinating with the WHO and foreign governments during disease outbreaks. But experts say the agency has been weakened by deep staff cuts, leadership vacancies and the Trump administration’s decision to cut ties with the WHO.

Trump has cut nearly 10% of the CDC’s workforce by early 2025, leaving fewer epidemiologists and scientists to do less work or coordinate responses across governments. There is currently no permanent CDC director or US surgeon general, both positions that play a critical role in responding to disease threats.

“They don’t have the right leadership at the CDC,” Evans said. “They’re like this on a ship without a leading captain, so they’re moving slowly and doing their best. There’s a lot of concern about it.”

Gostin said the CDC is lagging behind the WHO and European health authorities, saying the agency expanded its actions “one week after the international community began to confront a potential global health crisis.” The outbreak was first reported on May 2 to the WHO, which immediately took several measures, including sending an expert on board.

The CDC issued its first public statement about the outbreak on May 6 and its first health alert for American doctors on May 8, which warned of the possibility of imported cases. The agency confirmed that it sent a team on May 7 to the Canary Islands in Spain, where the ship arrived two days later, and a second team to Nebraska as part of the plan to evacuate the American passengers from the ship.

While the CDC is now working with the WHO, experts say the Trump administration’s decision to cut ties with the World Health Organization harms the US’s ability to respond to future outbreaks. For example, the US no longer has direct, automatic access to real-time information from WHO member countries about emerging health threats.

Neil Maniar, a professor of public health at Northeastern University, said the response to hantavirus is very different in 2020, when the CDC is working more closely with international partners during the Covid.

“That’s what it takes to respond effectively to these types of outbreaks, and that’s where the system has broken down,” Maniar said.

“We must bring back the technology and resources of our country to respond because there will be outbreaks in the future,” he added. “It should raise important alarms for everyone about our preparedness and ability to keep this country safe.”