made it highly virulent did not occur until about 4,000 years ago. The highly virulent version capable of transmission by fleas through rodents, humans, and other mammals was found in two individuals associated with the Srubnaya culture from the Samara region in Russia from around 3,800 years ago and an Iron Age individual from Kapan, Armenia from around 2,900 years ago. This indicates that at least two lineages of Y. pestis were circulating during the Bronze Age in Eurasia. The Y. pestis bacterium has a relatively large number of nonfunctioning genes and three "ungainly" plasmids, suggesting an origin less than 20,000 years ago. On September 8, 2016, the Y. pestis bacterium was identified from DNA in teeth found at a Crossrail building site in London. The human remains were found to be victims of the Great Plague of London, which lasted from 1665 to 1666. In 2021, researchers found a 5,000-year-old victim of Y. pestis, the world's oldest-known, in hunter-gatherer remains in the modern Latvian and Estonian border area. Events 496 were reported in the United States between 1970 and 2020. Cases have been found predominantly in New Mexico, Arizona, Colorado. California, Oregon, and Nevada. In 2008, plague was commonly found in sub-Saharan Africa and Madagascar, areas that accounted for over 95% of the reported cases. In September 2009, the death of Malcolm Casadaban, a molecular genetics professor at the University of Chicago, was linked to his work on a weakened laboratory strain of Y. pestis. Hemochromatosis was hypothesised to be a predisposing factor in Casadaban's death from this attenuated strain used for research. On November 3, 2019, two cases of pneumonic plague were diagnosed at a hospital in Beijing's Chaoyang district, prompting fears of an outbreak. The patient was a middle-aged man with fever, who had complained of difficulty breathing for some ten days, accompanied by his wife with similar symptoms. Police quarantined the emergency room at the hospital and controls were placed on Chinese news aggregators. On 18 November a third case was reported, in a 55-year-old man from Xilingol League, one of the twelve Mongolian autonomous regions in Northern China. The patient received treatment, and 28 symptomless contacts were placed in quarantine. In July 2020, officials increased precautions after a case of bubonic plague was confirmed in Bayannur, a city in China's Inner Mongolia autonomous region. The patient was quarantined and treated. According to China's Global Times,