Dr. Assefa Tulu, age 45, died June 24, 2004. Dr. Tulu joined the health department in 1997 and served for five years as the county’s lone epidemiologist. He was charged with tracking the health of the country, including the spread of diseases, such as syphilis, AIDS and measles. He also designed a system for detecting a bioterrorism attack involving viruses or bacterial agents. Tulu often coordinated efforts to address major health concerns in Dallas County, such as the West Nile virus outbreaks of the past few years, and worked with the media to inform the public. Found face down, dead in his office. The Dallas County Epidemiologist died of a hemorrhagic stroke.