A virus first found in chickens is implicated in human obesity

As someone who's struggled with his weight all his life (and who comes from a family with similar problems), I've long been fascinated with the science of weight and obesity; many years ago I listened to a Quirks & Quarks segment detailing the theory that the modern obesity epidemic was the result of a bird flu that affected our gut flora and changed our metabolisms to make us hungrier and more susceptible to convert the food we ate to fat. Read the rest

What you need to know now about H7N9 bird flu

Looking for a quick rundown of basic information about the new strain of bird flu that's infecting people in China? The Toronto Star's Jennifer Yang has a great, one-page breakdown that will get you caught up on just about everything you need to know — including how scared you should be. For the record, the answer to that is complicated. We aren't near a pandemic yet. But we do need to get a better handle on understanding how this virus works so we can stop it from spreading. It's a serious situation and the news is not all good news. But we don't seem to be at a point where anybody outside of China and the international public health community should be in an urgent crisis mode. Read the rest

Non-symptomatic cases make newly identified diseases less scary

If you've been following news about the H7N9 bird flu outbreak in China, it may be relieving to know that doctors are now looking for (and finding) people who are infected with the virus, but who appear perfectly healthy or who are just suffering from a mild case of the yucks. It's an important reminder that we identify new diseases when sick people show up, very sick, in hospitals. Just because those are the only people we know to have the disease, doesn't mean the disease makes EVERYONE that sick. Hidden in the background are often many, many people who shrug off a new flu the same way you or I have shrugged off an old, boring flu. This is context you should take into reading about every new disease. Read the rest

How deadly is bird flu?

The Centers for Disease Control and Prevention, and the World Health Organization, say that H5N1 bird flu kills some 60% of the human beings it manages to infect. Basically, it hasn't infected many people—because it can't be spread from person to person—but most of the people it does infect die.

But this might not be the full story.

After I posted a summary of the current controversies surrounding H5N1 research, I got an interesting email from Vincent Racaniello, a professor of microbiology at Columbia University Medical Center. Racaniello points out that the 60% death rate statistics are based on people who show up at hospitals with serious symptoms of infection. So far, there've only been about 600 cases. And, yes, about 60% of them have died.

However, they don't necessarily represent everybody who has contracted H5N1.

A death rate is only as good as statistics on the rate of infection. If you've got an inaccurate count of the number of people infected, your death rate is going to be wrong. And there's some evidence that might be the case with H5N1.

In a recent study of rural Thai villagers, sera from 800 individuals were collected and analyzed for antibodies against several avian influenza viruses, including H5N1, by hemagglutination-inhibition and neutralization assays. The results indicate that 73 participants (9.1%) had antibody titers against one of two different H5N1 strains. The authors conclude that ‘people in rural central Thailand may have experienced subclinical avian influenza virus infections’. A subclinical infection is one without apparent signs of illness.

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Scary science, national security, and open-source research

I've been following the story about the scientists who have been working to figure out how H5N1 bird flu might become transmissible from human to human, the controversial research they used to study that question, and the federal recommendations that are now threatening to keep that research under wraps. This is a pretty complicated issue, and I want to take a minute to help you all better understand what's going on, and what it means. It's a story that encompasses not just public health and science ethics, but also some of the debates surrounding free information and the risk/benefit ratio of open-source everything.

H5N1, the famous bird flu, is deadly to humans. Of the 566 people who have contracted this form of influenza, 332 have died. But, so far, the people who have caught bird flu don't seem to have contracted the disease from other humans, or passed it on. Instead, they got it from birds, often farm animals with whom the victims were living in close contact. H5N1 was first identified 14 years ago, and there's never been a documented case of it being passed from person to person.

But that doesn't mean such a leap is impossible.

That's because of how the influenza virus works. Influenza is made up of eight pieces of RNA, containing 10 genes, and they all replicate independently of one another and there's no system for error correction*. That means you have more opportunity for mutations to arise that change what the virus does and who it can infect. Read the rest