(Corrects to say plague is caused by a bacterium in second paragraph.)
Feb. 24 (Bloomberg) -- A Chicago scientist died of the plague after becoming the first U.S. researcher to contract the disease in more than 50 years, a government report said.
The man, a 60-year old university researcher who wasn’t identified in the report, was working with a weakened form of the plague bacterium that was previously thought to be harmless to humans. The case occurred in September 2009 and was described today in a report by the Atlanta-based U.S. Centers for Disease Control and Prevention.
Centuries after the bubonic plague killed millions of people in medieval Europe, the disease continues to infect more than 2,000 people worldwide each year, according to the World Health Organization in Geneva. Scientists who study the plague use the weakened bacterium, which has never been linked to a human illness and is excluded from the strict safety codes that regulate the study of other deadly germs, the CDC said.
“The severe outcome experienced by the patient was unexpected,” CDC scientists wrote in the report. “Researchers always should adhere to recommended use of personal protective equipment.”
An autopsy of the man revealed a previously unknown medical condition that may have made him more vulnerable to the illness, according to the report. He had a hereditary condition called hemochromatosis, which causes an excessive buildup of iron in parts of the body. Previous studies have shown that injecting mice with doses of iron while they are exposed to the plague increases their chance of getting sick.
The bacterium that causes pneumonic, bubonic and septicemic plague is called Yersinia pestis. The CDC tested the version of the weakened bacterium the man was working with to make sure it hadn’t evolved to become more deadly. They injected mice with high doses of the strain and compared it with similar weakened strains. Less than 3 percent of the animals died, suggesting the germ hadn’t become more virulent, the CDC said.
The plague is spread by rodents and the fleas that feed on them. Improved hygiene and knowledge about the disease has limited its global spread, according to the WHO. Early diagnosis and treatment can improve outcomes, and about 10 percent of reported cases of plague result in death, the WHO said.
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