The Elizabethkingia anophelis outbreak that has affected dozens in Wisconsin, Illinois and Michigan, killing at least 20, has been reported to the World Health Organization (WHO).

Elizabethkingia anophelis growing on a blood agar plate. Image/CDC's Special Bacteriology Reference Lab
Elizabethkingia anophelis growing on a blood agar plate.
Image/CDC’s Special Bacteriology Reference Lab

UN health officials say the current outbreak in the United States is the largest known outbreak of Elizabethkingia on record.

This does not include yesterday’s report of a second strain of the bacterium that has affected another 10 people, in which six died, in Illinois.

WHO says many potential sources of the bacteria have been assessed, including water sources, health care facilities, medications and personal care products, though no common source has been identified to date. Investigations are ongoing.

Although Elizabethkingia anophelis is commonly found in the environment, particularly in soil and water, it rarely causes illness in humans. A few small, localized outbreaks were reported before, usually in healthcare settings.

Since the transmission route of the bacteria remains unknown and bacteria primarily infects people with serious underlying health conditions further cases can be expected.