Jeff Parker (2006) via politicalcartoons.com
Another bird flu? Okay, so a bit of a misnomer, calling H7N9 "bird flu". All flus are bird flus.
Birds have different respiratory receptors than we do. For those who need a quick reminder, any article that mentions Hs and Ns, the spiky proteins on the outer membrane of the flu virus, is talking about influenza A (influenza A causes both seasonal flu and worldwide pandemics whereas influenza B only causes seasonal flu but does not cause pandemics.)
The H stands for hemagglutinin; it binds to a receptor while infecting a host. We have one kind of receptor, birds have another, and some animals like swine have both. The much more limited (in spread, not in illness to humans) influenza B hits humans and seals. Don't ask me why, I don't know, but its limited host range may help keep it from causing worldwide pandemics. The N stands for neuraminidase and helps the virus get released from cells to move on in its infective cycle.
There are 17 different Hs and 9 different Ns in every combo you can come up with, and birds get them all. Humans typically only get the first three, so the swine flu pandemic of 2009 was an H1N1, and the seasonal flu circulating this year is an H3N2, as well as influenza B.
Since even within a category flu viruses mutate rapidly, there's a new flu virus made each year. Last year's flu antigen is removed, this year's flu is inserted (there's room for three, so this year the trivalent vaccine has a 2013 H1N1, a 2013 H3N2 and a 2013 influenza B), and voila. Fear of "ZOMG a new vaccine that's untested!" is completely unfounded, since the process has been the same for forty years.
via political cartoons.com
Nonetheless, many people opted out of fear to get the seasonal flu shot in 2009 rather than the (actually circulating) 2009 H1N1 shot because it was "new". See
Glenn Beck and
Bill Maher for ill-informed vaccine advice that year.
Now, the process to create a new flu vax by growing them in eggs takes 6 months. That's why when we had a new flu, swine flu (2009 H1N1) show up in April 2009, a vaccine wasn't ready until 6 months later in October. There are a few companies that can grow it in a vat in 6 weeks, but it's unclear whether a novel virus that suddenly showed up would have vaccine available in large quantities any faster than in 2009.
In addition, some flus are more deadly for humans and for birds than others. The dreaded H5N1 is a high pathogenic flu that kills birds (and more than half the humans: 324 deaths out of 628 reported cases) who catch it. Luckily, it's very difficult for humans to catch H5N1 or to pass it to other humans when they do (human to human is aka H2H). And if a bird market or flock has H5N1, you know it because they die.
Low pathogenic bird flus like H7N9 aren't like that. The market or flock can be infected but the birds don't all die, so unless you're checking and doing surveillance, you won't know that. That means humans can be more readily exposed, and that's why H7N9 is becoming a tricky problem.
More below the fold.
Luckily for us, there are both reporters and flu bloggers reporting on the public health professionals and researchers who track this stuff. Among the best of the best in the former category are Helen Branswell, a Canadian health reporter whose latest in Scientific American is a must read:
An influenza A virus called H7N9 exploded onto the global infectious-diseases radar on April 1 when the World Health Organization revealed China had found three people infected with a new form of bird flu. Since then 77 cases (as of 1 P.M. EDT, April 16) have been confirmed, and the virus has spread from China’s largest megalopolis, Shanghai, and several surrounding provinces to the capital, Beijing, more than 950 kilometers to the north. And cases have proliferated at a startling pace: Infections with H7N9 have already outstripped the total number of H5N1 bird flu cases seen in all affected countries last year.
Whereas the new virus doesn’t seem quite as deadly as H5N1 (fatal in about 60 percent of known cases), it still packs a scary punch. To date 16 people have died from H7N9, and many others remain in critical condition. So far, at least, mild infections from this new strain are in the minority.
“This is very, very severe disease—and rapidly progressive,” Timothy M. Uyeki, an influenza epidemiologist at the U.S. Centers for Disease Control, said last week after Chinese doctors published a report in The New England Journal of Medicine on the first three cases. “It’s similar to H5N1, but it’s a little hard to make comparisons based upon three cases and limited data.”
To put into perpective, 60% case fatality with H5N1, 20% case fatality with H7N9, and something closer to a 15% case fatality with
SARS back in the 2000's (a novel coronavirus that spread from China to Toronto. It was difficult to catch and fatality was much greater in older patients than younger patients. In the West, it spread within hospitals to health care workers, causing significant alarm when the source was unknown).
There was a time I subscribed to Nature just to read Declan Butler, one of the best health reporters in the world:
Scientists do not yet fully understand how the H7N9 avian influenza virus is spreading in China, or why the pattern of sporadic human cases looks like it does. But mapping the risks of known factors in the past geographical spread of avian flu viruses and human infections might provide some clues.
Declan's done google mapping of both H5N1 and H7N9 (link in Declan's article), and
also written about the gene sequencing and what it might tell us as we go forward.
I would certainly be remiss if I didn't also mention Mike Coston's Avian Flu Diary, Crawford Kilian's H5N1 and the volunteer crew at Flu Wiki Forum (a noncommercial site I started eight years ago to track news stories), who not only pick up on news stories from the Western world, but dig into the available stories from Indonesia, China and elsewhere to crowd source cases.
Here's a recent piece from Bloomberg news, commenting on CDC's approach to all of this:
U.S. hospitals are being urged to head off a spread of the new H7N9 avian influenza by looking out for people exhibiting flu-like symptoms who have traveled to China or had contact with someone who has the illness.
The Centers for Disease Control and Prevention held a conference call with health-care professionals yesterday to review procedures for treating bird-flu patients and controlling infections, Erin Burns, an agency spokeswoman, said in an e- mail. The Atlanta-based agency today issued interim guidance on the use of antiviral agents to treat H7N9 infections.
CDC's own
update from April 26 is here:
The number of human infections with avian influenza A (H7N9) in China has risen to 109; with 23 deaths. There are still no reports of H7N9 in the United States. While there is no evidence of sustained human-to-human spread of this virus, CDC is taking routine pandemic preparedness measures to prepare for that possibility.
Here's one from
Jeff Nesbit in US News:
It's Time to Worry About the New Chinese Bird Flu
None of this is good.
Right now, 18 percent of the cases in China have ended in death. While this is still less deadly than the previous avian flu outbreak in China six years ago – the H5N1 bird flu virus eventually killed more than 300 people after spreading from China to other countries in 2006 – the death rate for this new Chinese bird flu epidemic is more than triple the mortality rate of tuberculosis in China today.
None of the above cited sources are "panicking" when they write about this. I wish the word would be retired; the only people who panic are politicians. Still, it's a word you'll see used whenever we write about flu because it's a convenient way of criticizing authors for NOT writing about something the critics want written (most critics don't bother writing themselves, I'll note.) Didn't you know diarrhea kills more people? Didn't you know [fill in cause] is waaay more important? Well, see graphic at top of post. They are all important. But today, we're talking about flu. Deal with it. And as an amusing side note I was struck by a recent
kos post:
Sure, I'll write about immigration and marriage equality even when the response is tepid. Meteor Blades will write about drones and environmental issues. Other writers will write about topics they care about despite a lack of community huzzahs.
We get it, we understand that our issues of interest might not be your issues of interest. But that's the thing: want to read about it? It's here and you're welcome. Don't want to read about it? I won't yell at you (so long as you're not Glenn Beck-level stupid), I promise.
And who knows? By discussing it, we might all learn something. Isn't that why we blog?
In any case, what can and should you do? Well, always have a few days worth of food, water and supplies at home for emergencies where you lose power or you're sick and don't want to go out. It's always good advice to pay attention to the news. And be open to hearing about a new vaccine when the time comes. It could be a life saver, and don't run away from it just because it's "new".
By the time it's "old", one way or the other, it could be too late to help you.