Flu: Still a problem, just not here

What a difference a year makes: At about this time in 2009, the world was still in the midst of the H1N1 “swine flu” pandemic, though cases had already trended down from their fall peak. Here at the end of 2010, flu has made barely a ripple.

In the United States, seasonal flu has been a non-story: The Centers for Disease Control and Prevention reported last week that flu activity is low by almost every metric: from the number of states where flu is widespread, to proportion of outpatient visits for flu-like illness, to adult deaths from pneumonia and influenza, to flu-related deaths among children.*

Here’s the map of flu activity in the US: By Dec. 18, only one state, Mississippi, was experiencing what is called “widespread” flu, the highest category:

And here’s the trend line for doctor visits for “influenza-like illness” — something that felt to the patient like flu. That black line is what the CDC considers the “epidemic threshold” for a flu season; this year’s case reports, the red line, fall below it:

But if there’s one thing that’s predictable about influenza, it is that it is going to behave in a not-predictable manner. That turns out to be true this year as well — because while the US is having a very mild season, the United Kingdom is getting punched. Look at this, from the BBC’s Health Desk, charting flu cases among adults — and note how close the current peak is to the peak cases during their swine flu epidemic:
The BBC is reporting that flu cases in the UK have risen by 50 percent in a week. Last weekend, the Telegraph reported that cases of flu serious enough to need intensive care had doubled in a week. And today, the Daily Mail is saying that Arrowe Park, a hospital in Wirral near Liverpool, has banned visitors in an attempt to slow down the spread of flu to vulnerable patients from the outside world.

Right now the UK seems to be alone in the intensity of its epidemic. Google’s Flu Trends (which doesn’t seem to sample the UK) is showing high search activity for flu-related terms only in Ukraine and Norway. (“High” is 4th on a scale of 1-5.) HealthMap, which does include the UK in its searches, shows hot spots only in England, Germany, and the east coast of Australia.

All of which makes it sound as though — for the US at least — flu is just not that much of a concern. That assumption would be a mistake, as two new articles underline. In Clinical Infectious Diseases, Jeffery Taubenberger (who recovered the virus of the 1918 pandemic) and co-authors remind us that 2010 marked the 500th anniversary of the first verifiable flu pandemic, suggesting that there are many more to come. And in the latest Scientific American, notable flu reporter Helen Branswell explores how little surveillance for flu there is at crucial chokepoints, such as pig farms, where new flus are likely to emerge. (Story is behind a paywall, but here’s the free podcast.) Branswell warns:

The 2009 influenza pandemic appeared to come out of nowhere. It started as what seemed like a lethal outbreak in Mexico, then spread north of the border. By the time health officials learned that the virus responsible for the alarming explosion of cases was new and an infection threat to most of humankind, they had no way to keep it from spreading around the world. By a stroke of luck, symptoms were mild in the vast majority of cases. What if next time we are not so lucky?

That question weighs heavily on the minds of influenza scientists and public health planners as they prepare for the next big outbreak. And there will be a next time.

*Frustratingly, the CDC doesn’t assign static links to its weekly FluView reports, so if you read this post after Dec. 31, that link may take you to a different report than the one this post references. I’m using data that was on the site Dec. 30 for week 50 of 2010, ending Dec. 18.

Update: Well, that was quick. The link above now goes to the FluView for the week ending Dec. 25. The number of states with “widespread” flu has risen to five: Alabama, Georgia, Mississippi, New York and Virginia. Things are picking up.

Update 2: But they’re picking up much more in the UK, and the spillover from flu cases is affecting hospital operations overall. The Guardian reported Dec. 31:

NHS pressure group Health Emergency today claimed a number of hospitals in East Anglia were on black and red alert, saying the NHS was already struggling as a result of the flu outbreak.

Chairman Geoff Martin said the James Paget University hospital in Great Yarmouth, Norfolk, yesterday declared a black alert – the most severe status level – and that the Norfolk and Norwich University Hospital was on red alert – one step lower.

He said: “We warned that hospitals would be forced on to black alert as the flu cases fill the available beds. Now it’s happening and we do not believe that the chaos is restricted to East Anglia. The NHS is now on the brink of the worst winter crisis in over a decade as the harsh reality of cuts to beds and staffing numbers is exposed with lethal consequences.”

Image: Mine, Brussels, July 2010


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