Elizabethkingia is often found in water and soil, but -- until now -- has seldom caused infections. So far, 54 Wisconsin residents have contracted the infection, CNN reports.
"We don't see 48 of the identical organism causing an outbreak like this very often," Michael Bell, deputy director for the Division of Healthcare Quality Promotion at the Centers for Disease Control and Prevention in Atlanta, told Wisconsin Public Radio. "In fact, this is probably the largest one we've seen."
RELATED GALLERY: Learn more about the deadliest contagious, infectious diseases
Deadliest contagious, infectious diseases
Rare blood infection hits Wisconsin, Michigan
HIV/AIDS: as of 2012, roughly 36 million deaths worldwide since discovery; 1.3 million deaths in 2013 alone
(Photo: HIV-infected T-cells under high magnification, via Getty Images)
Tuberculosis: caused between 1.3 and 1.5 million deaths in 2013
(Photo: Tuberculosis, via Science Photo Library/Getty Images)
Malaria: up to 855,000 deaths in 2013
(Photo: Malarial Parasite inside Red Blood Cell, via Getty Images)
Pneumonia: results in approx. 4 million deaths per year
(Photo: Microphotograph of diplococcus, bacterium responsible for pneumonia, via Getty Images)
Creuztfeldt-Jakob Disease: 100% fatal
(Photo: Creuztfeldt-Jakob Disease, via Getty Images)
Marburg hemorraghic fever: up to 88% fatal
(AP Photo/Denis Farrell)
Middle East respiratory syndrome: 41% fatal
(Photo: Getty Images)
Rabies: up to 100% fatal if left untreated
(Photo: Brain of a rabies patient showing negri bodies in the cerebellum, via Getty Images)
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Wisconsin and Michigan residents are urged to keep an eye out for symptoms such as fever, shortness of breath, chills or cellulitis. Many people who contracted the infection were over age 65 and had health problems and compromised immune systems.