Even so, the latest potentially exposed patients—from New Hampshire, Massachusetts and Connecticut—will not likely contract CJD, health officials noted in a statement. "The risk to these individuals is considered extremely low," said José Montero, New Hampshire Department of Health and Human Services director of public health, "but after extensive expert discussion, we could not conclude that there was no risk, so we are taking the step of notifying the patients and providing them with as much information as we can.”
In part, the low risk may be the result of the type of instruments used. In the Swiss patients from the 1970s the transmissions occurred via electrodes implanted deep in their brains for days, giving time for the transmission of infection. In contrast, the New England exposures involved tools that are less intrusive and used only for the duration of the procedures. The tools came with an imaging system that guides surgeons during operations, says Cindy Resman, a spokesperson for Medtronic, which made the instruments used on some of the patients.
Moreover, history might provide some comfort to the exposed individuals: None of the Pittsburgh patients has yet developed CJD in the 11 years since their exposures, although the incubation period for prion diseases can span decades.
Pathologists will examine the brain tissue samples of patient zero to confirm whether he had CJD, says Elizabeth Talbot, an associate professor of infectious disease at Dartmouth College and New Hampshire’s deputy state epidemiologist. “We have more to learn” about CJD, she says, “but thankfully it is a very rare disease.” Currently, there is no plan to test the infectivity of the surgical tools, which remain in quarantine and will likely be destroyed.