Dr Jonathan Read, a lecturer in infectious disease epidemiology in the Institute of Infection and Global Health, comments on the first reported death in North America of a human from H5N1 bird flu.
“It is not, perhaps, surprising that we have seen a human case of H5N1 in a developed country outside of SE Asia. The individual had visited China, where H5N1 is thought to have emerged in 2003 and has caused many human cases previously, and it’s likely that’s where they caught the infection. The risks of it spreading within Canada are extremely low: there have been more than 600 human cases worldwide since 2003 and there has been almost no evidence of human-to-human transmission reported for H5N1.
Put simply, it seems you catch H5N1 from handling sick birds, not from infected people.
What is currently much more worrying is continued mounting total of cases of a different type of avian influenza: H7N9. This strain of flu has caused more than 150 human cases in China and Hong Kong since it emerged just last year (2013).
It has killed about half of the people it has infected.
What makes it more worrying is that there is growing evidence that it can spread between people. So far, it doesn’t seem to do this easily but currently H7N9 represents a potential significant influenza pandemic threat should it mutate sufficiently to pass more easily between people.
Helping to understand
Our work in the Fluscape project in Southern China is helping us understand how diverse people’s immunity to influenza infections is, and we are currently working hard to understand how often people in the region are exposure to avian and swine influenza strains. Having a better understanding of how often these zoonotic infections normally occur and to whom, will help put threats like H5N1 and H7N9 into a proper context.
Schools are known to be important drivers in the spread of influenza and many other flu-like illnesses. I have been working closely with America’s Centers for Disease Control and Prevention to help understand how influenza spreads in US schools and how students interact with each other and the wider community.
This work will be critical to help predict how far and how fast a new influenza strain with pandemic potential may spread. It will also help inform how best the transmission may be mitigated through school or classroom closures.
Inevitably, there will be another influenza pandemic in the future. Historical records show that they occur every few generations or so (presumably as the immunity built up against them dies away).
They are difficult to predict with precision though and, as such, remain a key threat to the wellbeing and economic security of the United Kingdom.
A new £4M NIHR Health Protection Research Unit in Emerging and Zoonotic Infection to be based in Liverpool and working closely with Public Health England will be addressing just this type of challenge to protect us from such threats in the future.