The bacterial bloodstream infections that sickened residents of Illinois in 2016 were likely not attributable to a sudden outbreak caused by a single source, but rather represent a pattern of intermittent cases among critically ill patients, according to a new report from the CDC.
From Nov. 1, 2015 to Dec. 7, 2016, as many as 67 people in Wisconsin were sickened by a rare bloodstream infection known as Elizabethkingia anopheles. Sixty-three cases were confirmed. Four possible cases were never officially linked to the outbreak as isolates extracted from patients could not be compared to the other cases as they were no longer on hand. After the Wisconsin Department of Health notified the Illinois Department of Public Health of the outbreak in February, Illinois announced 10 people in the state had fallen ill with Elizabethkingia in April, though it was later determined this cluster of infections was related to a separate strain.
To discover whether the Illinois Elizabethkingia infections represented an increase in the amount of normal cases reported in the state, the CDC asked all 19 Illinois facilities where the infections occurred to report all cases of Elizabethkingia infections among patients from Jan. 1, 2012 to May 16, 2016. Fifteen facilities responded. The number of Elizabethkingia cases reported across the facilities for the given time frame was 77, amounting to a cumulative average of 17.1 cases per year.
"The evidence does not support a finding that the recently identified cluster represents an acute, point source outbreak, given the lack of common facility exposure among patients, and that the number of infections in 2014 to 2016 reported by facilities did not appear to be higher than in previous years, and the isolates from the 2014 to 2016 cluster matched environmental isolates from the 2012 to 2013 outbreak," wrote the study's authors. "Instead, this more likely represents ongoing sporadic infection among critically ill patients."
In total, there were 19 deaths associated with the infection in Wisconsin — with one death among the possible cases — and seven deaths in Illinois. Most of the patients infected were elderly and suffered from at least one underlying health condition.
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