A mysterious outbreak of an extremely rare bloodstream infection has been ongoing in Wisconsin for at least four months, and public health officials are unsure of the cause. The Wisconsin Department of Health has reported that 54 cases of Elizabethkingia anophelis infection have occurred since 1 November 2015. Elizabethkingia, an opportunistic pathogen that is abundant in the environment, has caused infections in at least 12 counties throughout the state and has been identified to be linked primarily to healthcare facilities. Symptoms of Elizabethkingia infection include fever, shortness of breath, and cellulitis . The majority of cases during this outbreak have been in patients over the age of 65, and all cases have had previously diagnosed underlying illnesses . To date, 17 deaths have been associated with the outbreak , and a case has also been confirmed in western Michigan .
The outbreak has created unique challenges for the Centers for Disease Control and Prevention (CDC) and for local health departments. In the past, infections from the bacteria had been so rare that they were not closely monitored, making it difficult to determine how many people are usually affected . Wisconsin typically only sees one or two cases per year according to University of Wisconsin infection control director Dr. Nasia Safdar. The CDC laboratory in Atlanta is currently the only laboratory in the United States that can distinguish E. anophelis from a different, more common species in the same genus, E. meningoseptica. Thus, samples often need to be sent to the CDC lab before cases can be officially confirmed .
At this point, the source of the unprecedented spread of the bacteria is unknown, making it difficult for health departments to prevent future infections. Five CDC “disease detectives” have been sent to Wisconsin for an investigation of the outbreak, which will involve reviewing medical records and interviewing patients to determine if a connection exists between the cases . Exposure from contaminated food and water had been identified as a potential risk factor, since the bacteria is so widely present in the environment. However, the water supply has been ruled out as a potential source of the infection after it tested negative for the presence of Elizabethkingia. No pattern of medical treatment or device usage has emerged among the cases, so it is not clear if a relationship exists between infection and specific type of treatment .
Another problem presented by Elizabethkingia anophelis is that it is difficult to treat with antibiotics . However, despite its multi-drug resistance, Elizabethkingia is not considered a true “superbug” as Wisconsin health officials have identified antibiotics to which the bacteria are susceptible. Dr. Safdar has said that the general public should not be concerned about the bacteria as it causes disease only in the small proportion of the population with compromised immune systems. Elizabethkingia is not known to be spread from person to person, and infection is believed to occur as a result of contact with contaminated medical equipment, though this has not been confirmed. Control of the outbreak will rely on diligent reporting from healthcare workers as well as the investigative efforts by public health officials . A rapid identification of cases occurred after the Wisconsin Department of Health Services initially provided guidance to health workers about identifying and reporting cases. This has led to an improvement in outcomes for patients as healthcare workers begin to administer proper treatment .