The Wisconsin Department of Health Services (DHS) has confirmed that 17 people have now died from a bacterial infection that has so far affected 54 patients, yet the source of the outbreak remains unknown. While there is nothing mysterious about the identity of the microbe responsible for the deaths, the extent of the current situation is unprecedented, and massively surpasses all previous outbreaks involving this particular microorganism.

Named after the scientist who first discovered the bacteria in the 1950s, Elizabethkingia anophelis is a common microbe that is found in soil and water. While most people who come into contact with the microbe suffer no ill effects, those with weak immune systems can become ill, as the bacteria colonizes their respiratory tract, leading to conditions such as pneumonia.

For this reason, it is most dangerous to very old or very young people, and is most commonly associated with meningitis in newborn babies. It can also pose a threat to those suffering from other conditions such as cancer, which could compromise the strength of their immune system.

Until now, the majority of known outbreaks had been very limited, often affecting only two or three individuals within a very narrow geographical area. Usually these stem from a nearby source where the bacteria has become concentrated, such as a sink or faucet.

However, the current outbreak has claimed victims from 12 different Wisconsin counties, with one case being reported in Michigan. All those infected are reported to be over the age of 65, and suffering from at least one other major health condition – which may explain their susceptibility to the bacteria.

"At this time, the source of these infections is unknown and the Department is working diligently to contain this outbreak," the DHS said in their statement.

Since the situation began in early November last year, the DHS and the Centers for Disease Control and Prevention (CDC) have been working to identify the precise strain of the bacteria responsible for the outbreak, and have found all samples to be genetically identical. This would appear to suggest that there is a single source, which makes the widespread nature of the outbreak even more puzzling.

Health officials are currently treating victims using a range of antibiotics, although success is largely dependent upon how early the infection is detected. In the meantime, CDC officials are interviewing patients and their relatives in order to try and pinpoint the source of the infection and determine how so many people from across the state came into contact with it.