Molecular genetics professor Malcolm Casadaban died September 13, possibly from the plague.
Casadaban, 60, was investigating a weakened laboratory strain of Yersinia pestis, the bacteria that causes the bubonic plague, in hopes of finding a better vaccine.
An initial autopsy revealed no other clear cause of death besides the weakened strain of Y. pestis, which grew in routine cultures of Casadaban's blood. More studies are being conducted to determine the potential role of the bacteria in Casadaban's death.
The strain Casadaban studied is used as a vaccine to protect against plague, and has been approved by the Centers for Disease Control and Prevention (CDC) for laboratory studies without the special safety precautions taken with harmful strains.
University officials contacted the Chicago Department of Public Health, the Illinois Department of Public Health and the CDC to investigate Casadaban's death, although there is no apparent threat to the public. There are no reported cases of illness by people Casadaban had contact with.
University officials said it is likely that Casadaban had a preexisting genetic condition, such as excess iron, which made him particularly vulnerable to the disease. Nonetheless, city health officials are still taking precautions and offering antibiotics to about 100 friends, coworkers, and family members of Casadaban.
Between 10 and 15 people typically develop plague in the United States each year, mostly in rural areas, according to the CDC, with one in seven cases being fatal. Antibiotics effectively treat plague but without quick treatment, plague can cause severe illness and death. Worldwide, about 3,000 cases are reported a year, mostly in developing countries.