Last week we got word of the first detection of a reassortment between the (formerly) pandemic H1N1 virus and a seasonal H3N2 influenza virus, which was announced by researchers in Toronto, Canada.
The case involved a 16-month-old boy from the Greater Toronto Area was admitted briefly to a local hospital for respiratory and gastrointestinal symptoms last January.
The child was sent home, and recovered without incident, and no other family members or contacts reported flu-like symptoms.
It wasn’t until later, when viral cultures showed a hybrid (reassorted) H1N1-H3N2 virus, did scientists realize that something unusual had occurred.
It is known that influenza viruses – if they co-infect the same host simultaneously – have the ability to swap genetic segments and form a hybrid.
This sort of reassortment can occur in any host; human, porcine, or avian.
Most of the time, these reassortments are evolutionary dead ends. They are either biologically unfit, or unable to compete with their better adapted parental strains, and fail to reproduce and thrive.
On exceedingly rare occasions, they can produce a competitive new virus - and as we saw in 2009 - spark a global pandemic.
Since both of the contributor viruses in this case are already widely circulating strains, concerns over this particular reassortment becoming a serious public health threat are slim.
But it does highlight the fact that reassortments can, and do, occur. And the importance of enhanced surveillance if we hope to detect the next pandemic flu threat early.
You can read a few more details on this case in the following Canadian Press article from last Friday.
By Sheryl Ubelacker, Health Reporter, The Canadian Press
On Thursday of next week (June 16th) a free webinar and Teleconference is planned as part of the OAHPP (Ontario Agency for Health Protection and Promotion) Grand Rounds that will provide the latest information and perhaps some additional insight on this reassorted virus.
Registration is Free and Easy on the Eventbrite website.
The details from the webinar announcement follow:
OAHPP Rounds: pH1N1 – H3N2: A Novel Influenza Virus Reassortment
Thursday, June 16, 2011 from 12:00 PM - 1:00 PM (ET)
Dr. Jonathan Gubbay- Medical Microbiologist, OAHPP
Dr. Natasha Crowcroft- Director, Surveillance and Epidemiology, OAHPP
Dr. Jonathan Gubbay, medical microbiologist at the Toronto Public Health Laboratory, will present on a new influenza virus that has been discovered by the Ontario Agency for Health Protection and Promotion (OAHPP). It is the first Canadian confirmed finding of a patient with a coinfection of seasonal H3N2 and pH1N1 followed by reassortment. To the best of our knowledge, this is the first case ever reported globally. The sample was submitted to OAHPP laboratories and testing identified co-infection and reassortment of the two viruses. These results were validated by National Microbiology Laboratory in Winnipeg.
The new virus is a hybrid of two viruses currently circulating in humans, both of which are covered by the current seasonal influenza vaccine (the H3N2 virus and the H1N1 virus). There have been no reports of additional cases or human-to-human transmission. Dr. Gubbay will be discussing the above case as well as molecular changes within the seasonal H3N2 influenza that have been seen this season.
Dr. Natasha Crowcroft will be the discussant, commenting on the public health significance of this finding.
I’ve already registered, and will make every attempt to attend via the webinar.