Major-General Sir David Bruce (29 May 1855 – 27 November 1931) was a Scottish pathologist and microbiologist who made some of the key contributions in tropical medicine. In 1887, he discovered a bacterium, now called Brucella, that caused what was known as Malta fever. In 1894, he discovered a protozoan parasite, named Trypanosoma brucei, as the causative pathogen of nagana (animal trypanosomiasis). Working in the Army Medical Services and the Royal Army Medical Corps, Bruce's major scientific collaborator was his microbiologist wife Mary Elizabeth Bruce (née Steele), with whom he published around thirty technical papers out of his 172 papers. In 1886, he was chairman of the Malta Fever Commission that investigated the deadly disease, by which he identified a specific bacterium as the cause. Later, with his wife, he investigated an outbreak of animal disease called nagana in Zululand and discovered the protozoan parasite responsible for it. He led the second and third Sleeping Sickness Commission organised by the Royal Society that investigated an epidemic of human sleeping sickness in Uganda, where he established that tsetse fly was the carrier (vector) of these human and animal diseases. The bacterium, Brucella, and the disease it caused, brucellosis, along with the protozoan Trypanosoma brucei, are named in his honour. Biography Early life and education Bruce was born in Melbourne, Australia, to Scottish parents, engineer David Bruce (from Airth) and his wife Jane Russell Hamilton (from Stirling), who had emigrated to Australia in the gold rush of 1850. He was an only child. He returned with his family to Scotland at the age of five. They lived at 1 Victoria Square in Stirling. He was educated at Stirling High School and in 1869 began an apprenticeship in Manchester. However, a bout of pneumonia forced him to abandon this and re-assess his career. He then decided to study zoology but later changed to medicine at the University of Edinburgh in 1876. He graduated in 1881. Medical career After a brief period as a general practitioner in Reigate, Surrey (1881–83), where he met and married his wife Mary, he entered the Army Medical School in Hampshire at the Royal Victoria Hospital, Netley. He passed the military examination in 1883 and joined the Army Medical Services (in which he served until 1919). For his first post he joined the Royal Army Medical Corps in 1884 and was stationed in Valletta, Malta. Bruce was appointed assistant