On June 19, Reuters first reported that dozens of workers at the Centers for Disease Control and Prevention had possibly been exposed to live anthrax and were being offered treatment such as antibiotics and vaccines. It's the kind of thing that no one ever wants to see happen, especially because anthrax has the potential to be exceptionally deadly. Luckily, the risk right now seems to be fairly low.
On June 13, workers noticed that samples of anthrax that they thought were dead were indeed alive. They were samples at a lab responsible for killing live anthrax before giving it to labs with less strict safety protocols for further work.
Reuters later reported that workers had made a mistake and only waited 24 hours to check if the anthrax was sufficiently inactive — rather than the required 48 — before giving them to other laboratories. The New York Times reports that the CDC was testing a new method for killing anthrax that employed chemicals rather than radiation. And according to the CDC, 84 workers were then possibly exposed.
So the anthrax didn't just get up and sneak over. It had some human help. (Though to be clear, there's been no evidence of foul play.)
The length of time it could take to develop symptoms ranges from a few days to two weeks (and even 60 days has been recorded). That means it will be some time before it's certain if people have escaped from danger.
On June 23, Reuters reported that the CDC has reassigned the director of the bioterror lab, according to two sources at the CDC who aren't allowed to talk to the press.
Why does the CDC have anthrax?
CDC is studying anthrax to better understand it and make new and better tests and treatments for it. The particular labs involved here were working on new ways to detect the dangerous pathogen.
Why does the CDC care about anthrax? One main reason is that the bacteria is a prime candidate for biological terrorism. The CDC calls it "one of the most likely agents to be used in a biological attack." The anthrax bacteria, Bacillus anthracis, has several features that make it especially well suited to bioterrorism. It's highly deadly. Because it's found in nature, it can be fairly easily sourced and grown. And it's highly stable and could be fairly well targeted to a specific population through food, water, or powder form.
The idea of an anthrax attack isn't just theoretical. In 2001, a week after September 11, intentional anthrax attacks through the US mail infected 22 people and killed 5. (Who did the attacks is still somewhat inconclusive.)
People also can get anthrax through contact with livestock like cattle and goats or products from these animals. But there's a vaccine that people can take if they're at risk.
Was anyone hurt?
So far no one has shown any symptoms, although it could be weeks or months until it's completely clear that no one's been harmed.
The CDC, in its official statement, says that the "the risk of infection is very low" and that it's giving people antibiotics "[o]ut of an abundance of caution." It also says that other workers, family members, and the public are not at risk. Person-to-person transmission is very rare.
It doesn't seem that the CDC is just blowing smoke. Joseph Kanabrocki, a microbiologist and safety specialist at the University of Chicago, told CIDRAP News that the chance of people getting sick is likely very low.
Update: Added new details on how the anthrax-inactivating procedure went wrong and about the reported reassignment of the bioterror lab director. Also clarified that more than one lab had received the live anthrax.
Correction: Corrected which laboratory found that the anthrax was alive.