For old times' sake I just visited WHO's tally of human H5N1 cases from 2003 to May 28, 2018. It confirmed my impression that H5N1, the original subject of this blog, seems to have vanished as a threat to humans.
As recently as 2015, H5N1 was diagnosed in 145 cases, 42 of them fatal (136 of the cases and 39 of the deaths were in Egypt). In 2016, just 10 cases and three deaths, all in Egypt. Indonesia had one fatal case in 2017; Egypt had three, with one death. No human H5N1 case has been reported at all so far this year.
This is quite a contrast from the early years. After its suppression in Hong Kong in 1997, H5N1 seemed to vanish until it returned in 2003 with one case in China and three in Vietnam, all fatal. The next year saw 46 cases and 32 deaths, and the disease had turned up in Thailand (17 cases, 12 deaths). By 2006, H5N1 was suddenly everywhere: Azerbaijan, Cambodia, China, Djibouti, Egypt, Indonesia, Iraq, and Turkey.
Nothing seemed to stop it, and circumstances seemed to encourage it: poultry smuggling is routine in many parts of Asia, public health systems are feeble, and countless families keep backyard flocks with minimal care. Those of us watching H5N1 in those days expected it to turn up in the Americas and Europe courtesy of modern air travel, whereupon we'd be in a full-blown, zombies-in-the-streets pandemic.
Instead, we were blindsided by H1N1 in 2009. It turned up almost simultaneously in Mexico and the US and then behaved just as we'd expected H5N1 to: a group of British schoolgirls went on holiday to Mexico and brought it back to the UK. (Having experienced Heathrow's swarming crowds, I can well imagine how it happened.) It was indeed a pandemic, but everyone complained about the absence of zombies.
Then H7N9 turned up, confirming avian influenza's ability to distract us with one threat while socking us with another.
By then I realized that no single disease could really be tracked alone; each is just another expression of a very complicated biosphere on which we pretend to impose various political systems. Some of those political systems regard outbreaks more as embarrassments than as existential threats, and many governments prefer to suppress news about them. I would not be surprised to learn that H7N9 has infected more people in China than Beijing has reported, or MERS infected more Saudis than Riyadh has admitted. Egypt went from 136 H5N1 cases in 2015 to ten in 2016, three in 2017, and zero so far this year. But I would not be surprised to know that it's still simmering away in the villages of the Nile delta.
And I would not be surprised if the next pandemic turned out to be a refurbished H5N1, or H7N9, or some other forgotten virus.