An Arizona-based wildlife biologist likely died of the plague, officials from Grand Canyon National Park announced on Friday. Autopsy reports for Eric York, a 37-year-old wildlife biologist for the National Park Service, showed that he had plague in his body. Officials said that 49 of York's coworkers and others who came within a 6-foot diameter of him were placed on antibiotics. As of Wednesday, they were still on medication, but none had become ill or displayed symptoms, officials said. Officials said York was most likely exposed to the plague when he performed an autopsy on a mountain lion that had been infected and most likely killed by it. York was the only person to come in contact with the dead mountain lion, according to officials. York presented symptoms of exposure on Oct. 30, three days after the mountain lion autopsy. He went to Grand Canyon Clinic, located on the South Rim of the Grand Canyon, with flu-like symptoms. York was sent home that day because the symptoms of plague are difficult to detect and are often confused with the flu, officials said. York, a lifetime wildlife enthusiast from Massachusetts, was found dead in his home on Nov. 2. York had been located at the Grand Canyon as an employee of the National Park Service for two years, officials said. His family will hold a private memorial service for him on Saturday. © Copyright 2007 USA TODAY, a division of Gannett Co. Inc. Conversation guidelines: USA TODAY welcomes your thoughts, stories and information related to this article. Please stay on topic and be respectful of others. Keep the conversation appropriate for interested readers across the map.