TORONTO – Scientists around the world are closely monitoring a bird flu strain that’s never been found in humans before but has killed four people within a week in China.
Experts at several research institutes around the world are urging officials to test animals and birds in affected regions for the deadly H7N9 virus, scrambling to understand how the transmission to humans happened and if it poses a public health risk.
It killed two people this weekend and by Thursday the avian influenza claimed another life – a 48-year-old man who died in Shanghai. This is the fourth death, meanwhile another seven are sick with the virus.
H7N9 has now exploded onto infectious disease experts’ radars as they consider if this influenza has the legs to morph into a global pandemic. In the latest reports, it appears that what was once a bird virus is now appearing in mammals. But human-to-human transmission does not seen to be a factor at play, so experts say there is no cause for alarm.
Global News spoke with two Canadian doctors, who are leading infectious disease research in the country. Here’s what they had to say about the influenza the world is watching with bated breath.
Dr. Michael Gardam is director of infection prevention and control at University Health Network.
Global News: What do we know so far about the H7N9 strain of bird flu? It hasn’t been a problem in humans before, so what sparked these outbreaks?
Dr. Kettner: We do not know very much yet about this specific H7N9 subtype, other than it has an avian host and has apparently been associated with at least some severe illness in humans. Avian H7 influenza viruses have caused outbreaks in poultry on farms and have occasionally infected humans in contact with these animals. One example was the poultry outbreak of the H7N3 virus in British Columbia in 2004. Although the influenza H7 viruses have caused serious disease in poultry, they have been associated with mild and infrequent illness in humans.
Dr. Gardam: I don’t think anyone knows what sparked these outbreaks. It is basically a bird pathogen. So there are many influenza virus subtypes out there, most of them do not readily infect humans. This particular combination of hemagglutinin (H) and neuraminidase (N) has been seen before, particularly in poultry.
Global News: In your opinion, is there a danger of this becoming an epidemic?
Dr. Kettner: In order for this H7N9 virus to become a human epidemic, the virus must be able to transmit from person to person. So far, there is no evidence for this having occurred with this virus.
Dr. Gardam: Nobody ever knows. We have a much more sensitive surveillance system now than when SARS showed up 10 years ago, so we are detecting new viral strains all over the place. The first sort of big scare like this we got was with the H5N1 virus in Hong Kong over a decade ago. The question always remains – so what? Is this a very isolated event or is this something that is actually going to emerge? The sad part of it is that you don’t know if it will emerge until it emerges.
Really, what you need to have is a strain which readily infects people and readily spreads between people. There are other factors as well – how sick does it make people, for example. There is nothing in this story that makes me particularly worried because it is such an odd strain and because we are so early on and because we get reports like this all the time. All you can do is watch it and see what happens.
Global News: What are the chances of this bird flu making its way to Canada?
Dr. Gardam: It always is a possibility – it is one of those things, because of modern air travel you could have somebody start to get sick, get on a plane and land in Toronto 12 hours later and there you go. That being said, this particular strain is not traditionally thought of as one that would be highly adapted to humans.
Dr. Kettner: We probably can’t yet predict very well how this H7N9 virus will affect bird species – such as how it might spread among birds as they migrate – or whether it will “jump” to other species. The avian H5N1 influenza virus has continued to affect poultry and some humans for over a decade, yet it still hasn’t crossed the Atlantic Ocean to the Americas.
Global News: So far, the death toll sits at 2. What do you think health officials in China need to do to contain this bird flu?
Dr. Gardam: One of the most important things, which they seem to be doing, to some degree, is be open about it. With SARS, China was not open about the SARS coronovirus so there was a lot second guessing about what was going on. Same with the novel coronovirus reported a few months ago – we all want to hear about what is going in real time. While there have been mathematical models and discussions about how to stop an influenza pandemic – in reality, you can’t stop these things. Once they get going they get going. Then your preparation is around general influenza and epidemic preparedness – having enough beds, working on a vaccine.
Dr. Kettner: We have been informed that Chinese health officials are on heightened alert, including enhanced monitoring for influenza-like illness. This would be appropriate, as would be the reinforcement of the prudence of usual and routine hygiene practice for humans and animals. Until more information about the extent, severity, and ways of spread, further containment measures beyond such precautions and monitoring would probably be premature at this time.
Global News: SARS and another virulent H5N1 strain that killed 360 people worldwide both originated in China and the Asia region. Why do these viruses tend to start there?
Dr. Kettner: We cannot say for sure, but there are a number of potential factors. These may include the large Chinese population and the close living circumstances amongst many of them, including close contact with poultry and other animals in some settings.
Dr. Gardam: What people have tried to do in countries that have had problems with H5N1 for example is try to minimize the contact between humans and poultry. One of the theories is that the majority of novel human pathogens come from animals. Where in the world do you have a big collection of animals and people? You have a very, very dense population, a fair amount of poverty still and you have humans and animals living in very close proximity. That being said, H1N1 probably arose in the US – that isn’t always the case. It used to be generally taught that these viruses always come from Asia, yet four years ago it came from the US.