In the wake of a deadly hantavirus outbreak aboard a cruise ship, some people have fears the virus could spark another pandemic similar to covid-19.
As conflicting claims spread online, Pittsburgh medical experts say it’s important to separate fear from fact. So what exactly is hantavirus, and should people be worried?
The current hantavirus situation is a public health concern, but not an epidemic or pandemic threat, according to Dr. Amesh Adalja, a Pittsburgh-based infectious disease specialist and senior scholar at the Johns Hopkins Center for Health Security.
“The public health procedures in place are intact and robust,” Adalja said Monday.
Transmission risk
Dr. Suresh Kuchipudi is professor and chair of infectious diseases and microbiology at University of Pittsburgh School of Public Health. He said while hantavirus is more deadly to humans compared to covid-19, it’s much less easily transmitted.
“One thing that made this more concerning is that this is the hantavirus version that we know can spread from human to human,” he told TribLive Monday. “That being said, it is important to clarify that this is not like covid-19 where you share the same airspace with someone and then you catch it from the air.
“What it requires is close contact.”
Kuchipudi said the leading theory is that transmission requires close contact with an infected person through respiratory secretions or other bodily fluids — meaning people cannot catch hantavirus simply by being in the same room with someone who is unmasked.
Adalja said the Andes hantavirus strain is the only known variant capable of limited human-to-human transmission.
“The Andes hantavirus is behaving exactly as we would expect it to,” he said. “I don’t expect that this will transmit into the general public.”
Kuchipudi said there are more than 20 different strains of hantavirus, and they mostly transmit from rodents to humans. The Andes version, which is what infected the cruise ship and can be transmitted human to human, is not native to the United States, but rather South America, particularly in the regions of Argentina and Chile.
“The rodents that carry these different strains are not the same in different places,” he said. “Deer mice carry (the) local strain in Pennsylvania.”
Deer mice are not the typical house mice people commonly encounter, said Kuchipudi.
He said hantavirus most often spreads to humans through contact with infected droppings or nesting materials in enclosed, poorly ventilated spaces — such as sheds opened during spring cleaning.
“The dried-up urine and the droppings of these rodents will have the virus, and the tiny little dust particles carry the virus,” he said. “You could inhale those.”
Precautions people can take to minimize the risk of exposure in this way include, Kuchipudi said:
- Open windows and doors to ventilate at least a half hour before entering closed spaces
- If people decide to vacuum, spray bleach solution, let it soak for 5-10 minutes contact time before wiping up with paper towel
- Wear gloves, especially if entering a closed-off shed
- Wear a respiratory protection N95-style mask (not a surgical mask) to protect from particles
- Wash hands thoroughly after cleaning
“Sometimes these particles are so small that you can’t see, but you inhale them,” he said.
Hantavirus has been known in the United States for decades, despite not having any recent cases, he said. Over the last 30 years of tracking the virus, he said there’s been fewer than 900 cases nationwide.
However, the issue has been the seriousness in those that do get infected, as Kuchipudi said there’s been up to a 30-40% mortality rate.
“It is important to recognize the risk,” he said. “(There are) currently no vaccines or treatment for this virus — which makes it even more riskier.”
Local risk?
As of Monday, Kuchipudi said risks to the public in the Western Pennsylvania region are “very, very low.”
“From that standpoint, we’re not really concerned,” he said. “Realistically, the risk is low but not zero, so there’s always a certain amount of caution that people need to exercise.”
Kuchipudi said the cruise ship outbreak reflects the growing threat of zoonotic diseases, as increased global travel and human interaction with animals create more opportunities for viruses to spread to people.
“More than 70% of emerging infectious diseases in humans — they originate in animals, meaning they’re zoonotic in nature,” he said. “It is critical we understand the intersection. Human health is inextricably connected to animal health and environment.”
Kuchipudi said the goal is to take a proactive approach to situations like the cruise ship infections.
“We do not want to wait for a disease to eventually become a problem in people,” he said. “That approach is pretty expensive, also the cost of containing an epidemic or outbreak, more importantly the impact of fear and scare of diseases, can all be mitigated if we can be proactive.”
Quarantine?
Seventeen Americans and a dual British-U.S. citizen evacuated from the cruise ship, CBS News reported, and on Sunday night, the Department of Health and Human Services said one American on the repatriation flight “tested mildly PCR positive for the Andes virus,” and another began showing symptoms.
Both passengers were “traveling in the plane’s biocontainment units out of an abundance of caution,” HHS said, according to CBS News. The passenger who tested positive was not experiencing symptoms, according to a statement from the University of Nebraska Medical Center.
Adalja said there is currently no official quarantine for hantavirus, but those coming back from being on the ship can either stay in the Nebraska Medical Center’s National Quarantine Unit or “elect for home monitoring.”
The Nebraska unit is the only federally funded quarantine unit in the United States.
“Those individuals coming from the ship need to be monitored for a six-week period to run out the incubation period,” he said.
Of the Nebraska group, 15 people were taken to the National Quarantine Unit at the medical center, while another person was taken to a biocontainment unit there, health officials said at a briefing Monday, CBS News reported.
The person in the biocontainment unit, which provides hospital-based care, was “doing well” as of Monday morning and did not have any symptoms, according to Angela Hewlett, an infectious disease physician and the medical director of the Nebraska Biocontainment Unit.
The incubation period — meaning the time somebody is exposed to hantavirus to the time they start showing symptoms — could last anywhere from one to eight weeks, according to Kuchipudi. Whereas, for covid-19, the incubation period is under three to five days.
“Even after getting exposed to a rodent-infested place, (there’s a) possibility of developing symptoms weeks later,” he said.
Additionally, hantavirus symptoms aren’t specifically distinguishable from a seasonal flu-type infection, Kuchipudi said. It can escalate to shortness of breath and difficulty breathing, though, he said.
“Any kind of unexplained illness, even though it may look like flu, if you suspect a possible exposure to rodents … it would be really important to see a primary care physician and get tested to rule out this infection,” Kuchipudi said. “I think everybody who was on the cruise ship has been monitored.”
The key will be whether any secondary transmission occurs from the cruise passengers to family members, friends or health care workers, he said.
“(There’s) no evidence of secondary yet,” Kuchipudi said. “That also tells us how easily the human to human transmission is happening — it’s not that easy.”
The coordinated global effort of everyone monitoring the outbreak situation is a good sign and will help determine the risk level moving forward, he said.
“This outbreak also is a stark reminder that any new or reemerging infectious diseases are threats; they do not all necessarily look like covid,” Kuchipudi said, and could be more or less dangerous and/or transmissible. “It is really critical for all of us to recognize that even though the risk is low, with these viruses, things could change very quickly, especially with a disease much more severe than covid-19 and no effective treatments.
“As things change, we let people know.”
Recommendations and guidance from medical professionals could change in the coming days as facts become available in the hantavirus cruise outbreak, according to Kuchipudi.
“This is also partly what contributed to the mistrust in the public during covid because people perceived that the recommendations and the guidance kept changing,” he said. “It was a brand new virus, and we were learning as we were handling the outbreak — that’s fundamentally how science works.
“That’s not somebody changing the narrative … as new facts become available we are open to changing our understanding.”