An unheralded yet costly flu-like virus to hit the province hard, according to UAlberta research
UAlberta virologists forecast severity of upcoming respiratory syncytial virus, responsible for more than 30 per cent of hospitalized respiratory cases annually.
By MICHAEL BROWN
A little known yet potentially deadly flu-like virus promises to keep Alberta’s emergency rooms busy again this season, according to new UAlberta research.
Virologist David Marchant and his Pulmonary Research Group found that it will be another nasty season for the respiratory syncytial virus (RSV), which often masquerades as a bad cold in adults, while in the elderly and youngsters, it often means a trip to the hospital and, in the most severe cases, being put on a ventilator or even death.
From September 2015 to August 2016, there were about 12,500 positive tests for RSV in Canada. This past year, that number almost doubled to 23,000. Marchant says 2017-18 should rival last year.
“If you go to hospital with RSV, you are more likely to be admitted,” he said, adding that RSV can be responsible for more than 30 per cent of all hospitalized respiratory cases in any given year.
For infants, RSV is the leading cause of hospitalizations in Canada and the U.S. In developing countries, the World Health Organization reports respiratory infections such as those caused by RSV are the leading cause of death.
If you haven't heard of this affliction, you're not alone. While discussing RSV research at a conference at Oxford, Marchant said even those in attendance were at a loss. While everyone had heard of the flu and HIV, he contends the far bigger problem is RSV.
“I think one of the reasons there’s so little awareness surrounding RSV is because it preys on those who can’t speak for themselves, mostly infants,” he said. “It’s responsible for more than 100 million respiratory infection hospitalizations annually around the world. It kills about 100,000 people annually, 10 times more infants than influenza does in a year.”
Marchant said that while influenza is primarily a problem in people with pre-existing conditions, RSV can cause severe disease in those who were otherwise completely healthy.
“We’ve all had it, but unlike the flu—to which we mount a large immune response to because of something called immune memory—RSV somehow suppresses or evades the immune memory response,” said Marchant. “With the flu, we develop an almost life long immunity to it. If your remember, there were 90-year-olds immune to H1N1 flu pandemic in 2009 because there were exposed to it during an outbreak in 1918.
“With RSV, however, we’re infected by the exact same strain over and over again due to this loss or lack of immune memory.”
Another reason for RSV’s relative anonymity is because there is no known cure or vaccine, and the treatment for it is preventative and very expensive. Marchant said the lack of research and funding invested in RSV has left a void in the knowledge surrounding this tricky virus.
“In terms of a vaccine for RSV, if you inactivate RSV in the traditional way like they do with other pathogens to make a vaccine, you actually enhance the disease when you get exposed to the virus,” he said. “A 1960s vaccine trial for RSV caused the death of two infant vaccinees as a result of enhanced RSV infection.”
What’s more, Marchant said a longer term problem with RSV is that if you get it early in life, it mechanistically predisposes you to asthma and chronic obstructive pulmonary disease, often decades later.
Finding can be used to plan upcoming season
Marchant’s team used cutting edge tools in the Li Ka Shing Institute of Virology on RSV samples from the Alberta Public Health Laboratories to sequence the virus to determine its “nastiness” and level of replication. This work led to the prediction that this year’s harsh outbreak in the province will be due primarily to the emergence of two strains of RSV—ON1 and BA.
“Canada spends at least $50 million to treat RSV infections per year,” he said. “With our findings, we should be able to accurately allocate funds for health care when we know the extent of the impending burden. Administrators can plan to bring in a certain number of ventilators and open new beds.”
Using new and faster ways to purify RSV, Marchant’s team is continuing to develop therapeutics for RSV, but he admitted even if they found something tomorrow, clinical use would be a decade or more away.
The research was a collaboration between Marchant’s lab and colleague Bart Hazes and provincial microbiologist Steven Drews at PROVLab in Edmonton. Drews provided clinical guidance and over 100 RSV isolates from patients in recent years to our laboratory. The study was published in the journal Viruses and then in Scientific Reports.