The last case occurred on Nov. 16, when a 94-year-old woman in Connecticut was admitted to hospital with fever, cough, and weakness. She died on Nov. 19 and her exposure was linked to cross-contamination from one or more of the suspect letters.
Whether all the lessons of those events have been learned is an open question.
Government officials, understandably, think the answer is yes. In an interview published by the Trust for America's Health, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, argued that "today we are in a much better position" as a result of the broad response to the anthrax attacks.
He cited new bio-containment labs and bioterror research centers of excellence, better procurement for vaccines, drugs, and diagnostics that might be needed, and better coordination among the players.
Those "substantial and wise" investments were aimed at closing what Fauci called the two major gaps that existed a decade ago -- lack of basic and applied research into vaccines, diagnostics, and therapeutics and the absence of "a clear public health response system."
But, after 10 years and "a huge investment" in bioterrorism resources, the tripwire for another attack is still the same as it was, according to Dr. David Relman of Stanford University in Stanford, Calif.
Some "astute clinician" is going to pick up the first signs of any new attack, he told MedPage Today. And the only certainty is that "the next attack will not look like the last."
Are doctors ready for that?
Those in the infectious disease field are highly aware of their role as a "biosensor," according to Dr. Peggy Neill of Brown University in Providence, R.I. But for doctors in other fields, consciousness of the issue has "probably somewhat receded," she told MedPage Today.
A challenge, she said, is sustaining "interest and expertise among very different groups of clinicians and I don't think we yet quite have an answer to that."
Investment in new reference labs and in surveillance systems is useful and important, Neill noted. "The testing network is much, much better than it was before," she said.
But the major gap is that it is still not possible to say -- on any given day on a real-time basis -- how many cases of botulism or pneumonia or unexplained rash are in hospitals around the nation, she said.
In a retrospective article in Annals of Internal Medicine, Bush and co-author Maria Perez, MD, also of JFK Medical Center, argued that "many aspects of the 2001 anthrax attacks went well."
Specifically, the pathogen was quickly identified, post-exposure prophylaxis was successfully deployed, rapid diagnosis and multi-disciplinary care reduced mortality compared with historical rates, and both medical personnel and lay volunteers leapt unto the breach "during a time of fear and uncertainty."
On the other hand, knowledge about anthrax was outdated and inaccurate, vaccine administration was confused and delayed, and there was considerable hoarding of antibiotics.
Perhaps most important, Bush and Perez argued, established "syndromic surveillance systems" failed to pick up the attack, although several cases already existed by the time Stevens walked into the ER.
Bush told MedPage Today that syndromic surveillance is never going to be enough. By the time the data is collated and someone notices a pattern that indicates bioterrorism, "you're way behind the curve."