These days I spend some of my time talking to virologists about a new virus that can move from quickly host to host. It uses a route that we don’t yet understand very well. But we need to find out, because the virus has an unknown potential to wreak havoc on the economy and to give rise to a new pandemic. I’m keeping tabs on companies scrambling to design new vaccines against the new virus, drawing up plans to manufacture them in huge quantities if needed in an emergency.
I am not reporting about Covid-19 (which is not to say Covid-19 is gone, of course). Instead, I’ve started helping the New York Times with its reporting on a strain of H5N1 avian influenza that’s spreading among cows.
I’m glad to pitch in, because it’s a story that needs telling. But I really wish my colleagues and I didn’t have to tell it. I especially wish that I didn’t hear so many echoes from early 2020, at the start of the Covid-19 pandemic.
There’s been a lot of news to track over the past few months, and so I wouldn’t be surprised if you have let the bird flu saga fall off your radar. Here’s a quick recap, featuring links to great stories by my colleagues Emily Anthes and Apoorva Mandavilli.
Influenza viruses have their ultimate source in birds. As I wrote in A Planet of Viruses, the birds experience the flu as a gut infection and poop out the virus in their droppings. There’s a vast diversity of influenza viruses in birds, and it’s in constant flux as the viruses mutate and mix their genes together. Sometimes a new strain will emerge that turns out to be very transmissible, or deadly, or both. In the early 2000s, H5N1 emerged and started infecting not just birds, but people who handled birds for a living. Some people got infected, and some of the infected died.
Public health officials and virologists alike worried that H5N1 might evolve into a virus that could readily grow in the airway instead of the gut, and could move readily from person to person. Without any immunity to this new virus, people would be easily infected and might suffer high mortality rates.
I wrote a few stories about those worries in H5N1’s early years, and I have been revisiting that time in my research for my upcoming book. (More on that soon!) In 2024, I’m struck by the enduring influence that the fear of H5N1 has had. We still feel it today.
Back in 2012, for example, I wrote about how the threat of a spillover led to some controversial experiments. Two teams of researchers tried to figure out the mutations that H5N1 would need to make the jump from bird to human—or at least to mammal. Those experiments fueled the “gain of function” debates. Some scientists worried that the experiments might accidentally produce a new pandemic virus that might escape from the lab. Publishing the results might enable someone to create a new pathogen from scratch.
Those debates have continued for over a decade. As I wrote with Jim Gorman in 2021, the disputates got particularly contentious during the Covid-19 pandemic. This May, Ben Mueller and I wrote reported on how they have now led to new rules for experiments on dangerous pathogens.
The fear of H5N1 also spurred President Bush to make preparations for pandemics. In 2005, when his administration unveiled their plan, they had influenza in mind. Fifteen years later, when a coronavirus showed up in the United States, public health officials responded with that H5N1 plan in mind. But Covid-19 turned out to behave differently in some significant ways, which took time to discover—and that lag allowed the pandemic turn into an even worse disaster.
Despite two decades of anxiety, H5N1 has yet to make the jump to humans. That doesn’t mean it has faded away, though. It still burns through poultry farms, requiring the slaughter of huge numbers of birds to slow its spread. Such drastic measures can’t stop H5N1 for good, however, because it also infects wild birds that can deliver it by air to new victims around the planet.
In the past couple years, as it has traveled the globe, H5N1 has evolved into a new lineage that is attacking birds and mammals with unprecedented savagery. It infects polar bears, penguins, elephant seals, and a host of other species.
Then it came after cows. The first hints of trouble turned up in January, as some cows in Texas suffered drops in milk production. The US Department of Agriculture announced in March that cows across three states were infected.
Researchers have long known that cows can potentially get infected with some strains of influenza. But H5N1 had never infected them before, and it is now creating an epidemic unlike anything cows had previously experienced with influenza.
Scientists are looking at the epidemiology of this “cow flu,” and carrying out laboratory experiments on it, to understand its spread and its potential for trouble. My contribution to the newspaper’s coverage of this new outbreak comes from some reporting I did last week on a very unusual kind of experiment: intentionally giving cows the flu inside high-security biosafety labs.
The results of this small experiment offer some cause for hope: the virus appears to be bad at spreading as a respiratory disease—for now at least. Instead, the research suggests, dairy farms are spreading the virus from one udder to another on milking equipment. That may mean that a concerted, focused effort on stopping the flu’s spread could rein it in.
But this is no reason for complacency. H5N1 is knocking harder on our door than ever before. It’s one thing for the virus to kill off some elephant seals on a remote beach in Chile. It’s quite another for a virus to be raging through the nine million dairy cows in the United States, overseen by tens of thousands of farm workers. So far, only four cases of cow-to-human infection have been documented. Three of those victims suffered little more than pink eye. But people are continuing to be exposed to the virus, and they may expose other people as well.
Imagine another worker getting a splash of virus-infected milk in the eye, then coming home, wiping the virus on a doorknob, and infecting their immunocompromised grandfather. People with weak immune systems can become evolutionary laboratories for influenza. They can’t eliminate the virus, but they do provide enough of a challenge to favor viruses with new mutations that let them evade attacks. Over the course of months, the viruses can further adapt to the human body. And when that grandfather sheds his evolved cow flu viruses, they may become something far more dangerous.
Think of it as nature’s relentless gain-of-function experiment. I really hope that this beat ends soon.
And In Less Dire News…
I still have time to write about other stuff! Such as: how Denisovans thrived for 100,000 years at the roof of the world, how the last woolly mammoths were wracked by genetic diseases and yet lived for thousands of years on a Siberian island, how we don’t need language to think, how flounders got their epic side eye, and how paleontologists may have gotten one of our earliest fish-like relatives upside down.
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