WEDNESDAY, June 29 (HealthDay News) -- In 2009, a 60-year-old American lab researcher was mysteriously, and fatally, infected with the black plague while conducting experiments using a weakened, non-virulent strain of the microbe.
Now, a follow-up investigation has confirmed that the researcher died because of a genetic predisposition that made him vulnerable to the hazards of such bacterial contact.
The new report appears to set aside fears that the strain of plague in question (known by its scientific name as "Yersinia pestis") had unpredictably mutated into a more lethal one that might have circumvented standard research lab security measures.
"This was a very isolated incident," said study co-author Dr. Karen Frank, director of clinical microbiology and immunology laboratories in the department of pathology at the University of Chicago Medical Center. "But the important point is that all levels of public health were mobilized to investigate this case as soon as it occurred.
"And what we now know," Frank added, "is that, despite concerns that we might have had a non-virulent strain of virus that unexpectedly modified and became virulent, that is not what happened. This was an instance of a person with a specific genetic condition that caused him to be particularly susceptible to infection. And what that means is that the precautions that are typically taken for handling this type of a-virulent strain in a lab setting are safe and sufficient."
Frank and her UC colleague, Dr. Olaf Schneewind, reported on the case in the June 30 issue of the New England Journal of Medicine.
According to the National Institutes of Health, prairie dogs, rats and other rodents, and the fleas that bite them, are the principle carriers of the bacteria responsible for the spread of the deadly plague, and they can infect people through bites.
In the 1300s, the so-c
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