In 1969, Sommer joined the Public Health Service as an Epidemic Intelligence Service (EIS) officer at the Centers for Disease Control and Prevention, and moved overseas with his family to work in the Cholera Research Laboratory in Dhaka, Bangladesh (then known as East Pakistan), where he conducted the first formal epidemiologic investigation of a major disaster: the 1970 cyclone that washed away a quarter of a million people in a single night. He assisted Bangladeshis in their Liberation War and, in 2013, the Bangladesh government bestowed upon him the “Friends of Liberation War Honour” for his contributions during the revolution.