While a recent outbreak on a cruise ship has put hantavirus back in the headlines, a top University of Alberta virologist is urging calm.
Lorne Tyrrell, Distinguished University Professor of Medical Microbiology and Immunology and founding director of the Li Ka Shing Institute of Virology, says it's true that the virus carries a high mortality rate, but infection is rare and largely preventable by following a few basic hygiene tips.
"This is very unusual to see person-to-person transmission of a hantavirus, and I do not believe there's any major risk of any kind of widespread outbreak related to this unfortunate incident," Tyrrell says.
The current cruise ship outbreak in South America involves the rare Andes strain, which is known to be capable of person-to-person transmission. The World Health Organization is monitoring the 147 passengers and crew who were aboard the MV Hondius, reporting eight cases and three deaths so far.
"The couple who were first diagnosed may have picked up hantavirus in southern Argentina even before they got on the ship and then developed the disease on board, and passed it on to the people who were in close contact, such as those looking after them," says Tyrrell.
In North America, hantavirus is spread by inhaling or touching infected rodent urine or feces. About 200 cases have been reported in Canada and 77 in Alberta since the disease was first reported, Tyrrell says, with 10 new cases each year in our province.
"As an infectious disease specialist, I've never heard of a case of person-to-person transmission from the virus here in Alberta or Canada," he stresses, noting that hantavirus is far less contagious than either COVID-19 or bird flu, two other recent animal-to-human threats.
Hantavirus was first reported during the Korean War, when about 3,000 people developed a mysterious new illness that was later named after the Hantan River in North Korea.
The Asian version of hantavirus tends to cause renal disease and hemorrhagic fever, while the strain most common in North America usually attacks the lungs, leading to hantavirus cardiopulmonary syndrome. There is no antiviral treatment or vaccine available.
The virus takes two to four weeks to incubate after exposure. Symptoms usually start with fever, sore muscles and headache, much like the flu. Up to six days later, the pulmonary phase can begin, leading to difficulty breathing. These patients must be given intensive ventilation in the hospital.
Between 30 and 40 per cent of people who develop hantavirus cardiopulmonary syndrome will die, Tyrrell says.
In Canada, hantavirus is associated with mice infestations in rural areas. Deer mice are common across the country. Although the virus does not affect the animals' health, humans such as farmers, hunters, forest workers, even cabin owners or gardeners with a compost pile, should be wary of exposure.
Tyrrell has had to deal with mice in the granary on his farm. He warns against sweeping or vacuuming mouse droppings and urine, and advises leaving them undisturbed and exposed to air.
"You can spread the virus by touching or inhaling mouse droppings and urine," he cautions. "If you're going to work in an area that has had mice in it, don't go in and try to clean it up immediately. The first step is to ventilate."
Next, mix bleach with water and spray it on the affected area to inactivate any virus that may be present. Allow it to dry. Once you're ready to remove the droppings, be sure to wear a mask and gloves.
While researchers like the U of A's Maya Shmulevitz are currently investigating potential vaccines, the best defence against hantavirus remains prevention.
By keeping rodents out of living spaces and using proper decontamination techniques when you do find signs of them, the risk of infection to the general public is extremely low, Tyrrell says.
