Hantavirus: What it is, how it spreads, how often it's fatal

Hantavirus, the rodent-borne pathogen blamed for the death of concert pianist Betsy Arakawa, the wife of actor Gene Hackman, is a rare but often fatal virus that has killed at least 34 people in Canada over the past three decades.

Arakawa, 65, died of hantavirus pulmonary syndrome in mid-February, roughly a week before the 95-year-old Hackman died of heart failure, likely brought on by his dementia and his inability to care for himself, according to the chief medical investigator for New Mexico.

What is hantavirus?

Multiple hantaviruses have been reported around the world, and all are spread by rodents such as rats and mice. Five species in North America are known to carry hantaviruses, three of which are commonly found in Canada: the deer mouse, white-footed mouse and red-backed vole. 

In humans, a hantavirus infection can cause serious diseases. The most common illness from an infection in North America is hantavirus pulmonary syndrome, an often severe respiratory disease that typically begins with flu-like symptoms.  

How can you contract hantavirus?

Humans can contract a hantavirus infection through indirect contact with the waste of an infected rodent. This includes simply inhaling virus particles when vacuuming or sweeping a rodent's urine, droppings or saliva.   

Humans can also be infected through direct contact, such as touching objects or eating food that has been contaminated by an infected rodent, or from a rodent bite. 

WATCH | More info on deaths of Gene Hackman and Betsy Arakawa: 

Gene Hackman died of heart disease 1 week after wife died of hantavirus

3 days ago

Duration 2:49

U.S. investigators say Oscar-winning actor Gene Hackman likely died of heart disease one week after his wife Betsy Arakawa died of hantavirus in a separate room in their New Mexico home. Police say Hackman’s dementia was a likely contributor to his death.

How rare is it?

Since surveillance began in the early 1990s, 163 cases of hantavirus pulmonary syndrome have been confirmed by the National Microbiology Lab in Winnipeg, part of the Public Health Agency of Canada, said David Safronetz, the lab's chief of special pathogens, in an interview with CBC News on Monday. That works out to an average of roughly five cases in Canada each year. 

A 2020 report led by National Microbiology Lab scientists showed a geographic breakdown of confirmed cases, with more than half found in Alberta (73), followed by smaller numbers in Saskatchewan (28), British Columbia (16) and Manitoba (5).

Only one case of transmission to humans in Canada was reported east of the Prairie provinces, in Quebec. Researchers believe this is because of genetic differences between the hantaviruses carried by rodents in eastern and western parts of North America.  

Of the 143 confirmed Canadian cases in that 2020 report, 34 were fatal.  

What are the symptoms of an infection, and how is it treated?

The symptoms of a hantavirus infection can appear anywhere from one to eight weeks after exposure, but on average appear after two weeks. A person suffering from hantavirus pulmonary syndrome can show a range of symptoms that include severe fatigue, fever, muscle pain, headache and nausea, and can progress to difficulty breathing. 

There are no antiviral medications available to treat a hantavirus infection. The typical course of treatment involves admission to intensive care, where the medical team will try to ease the patient's symptoms, including by providing oxygen and putting them on a ventilator.

WATCH | How you can reduce your risk of hantavirus infection: 

Hantavirus expert on how to reduce your risk of infection

6 hours ago

Duration 0:58

David Safronetz, chief of special pathogens at the National Microbiology Lab, says most hantavirus infections in Canada happen in the spring and early summer, often when people are cleaning up after mice when opening a space that has been closed for the winter like a cottage. He outlines what people can do to reduce their risk of getting infected.

How deadly is it?

Reported fatality rates from hantavirus pulmonary infection ranges anywhere from 20 to 50 per cent, depending on the strain of the virus. 

The fatality rate in British Columbia is about 44 per cent, according to a 2023 report by the B.C. Centre for Disease Control.

In 2015, the U.S. Centers for Disease Control and Prevention pegged the overall fatality rate at 36 per cent. Given the high fatality rate, researchers have described it as "one of the most severe infectious diseases endemic to the United States." 

How can you prevent it? 

Most hantavirus infections in Canada happen in the spring and early summer, often because that's when people are entering enclosed spaces where deer mice have been active, combined with seasonal increases in deer mouse populations. 

Health experts advise if you are opening a cabin, cottage or trailer that's been closed for the winter, air out the structure as much as possible and wear a mask and gloves when cleaning any mouse waste to prevent transmission of the virus. 

The rodents that carry hantavirus don't show signs of sickness themselves. Safronetz says the vast majority of infections in North America are believed to originate with deer mice carrying the Sin Nombre virus, the strain of hantavirus that is most commonly transmitted to humans.