Graduating in 1945 with a degree in medicine, he served two years as an intern before being employed at Arua Hospital as an assistant medical officer.
[1] Shortly before Uganda's independence, the National Assembly elected Lumu to lead the country's health ministry.
Relying heavily on technical staff, he promoted a plan to create a network of regional referral hospitals in a 10-year period.
[1] Accusations that he unethically acquired property in Kampala and Mukono districts led him to be called to testify before the Land Commission in 2018 in his last public appearance.
[5][6] While his family was planning to celebrate his upcoming 104th birthday, Lumu fell ill with a cough and developed pneumonia, dying on 11 December 2019 at his home in Bakuli, Rubaga Division, Kampala.