Bruce, Sir David (1855–1931), bacteriologist and parasitologist, was born in Melbourne, Australia, on 29 May 1855, the only son of David Bruce, of Edinburgh, and his wife, Jane, daughter of
Alexander Hamilton, of Stirling. His father was presumably an engineer, who went to Australia to install a crushing plant in a goldfield near Sandhurst, about 100 miles from Melbourne. When Bruce was
five years old the family returned to Stirling in Scotland, and he attended Stirling high school until he was fourteen. He then worked for three years in business in Manchester. From his early
interest in natural history he turned to the pursuit of athletics and boxing, until a severe attack of pneumonia intervened.
In 1876, at the age of twenty-one, Bruce entered the University of Edinburgh to read zoology. However, he was advised by a fellow student to study medicine, and he graduated MB CM in 1881. After
qualifying Bruce's first position was as assistant to Dr Herbert Stanley Stone, at Reigate in Surrey. It was here that Bruce met his future wife, Mary Elizabeth Sisson (1849–1931), daughter of John
Sisson Steele MRCS, Stone's predecessor in the practice. They were married in 1883, and began a lifelong partnership in science and travel; there were no children.
Shortly after their wedding Bruce was commissioned a surgeon in the Army Medical Service, and passed first from the Army Medical School at
Netley, on Southampton Water,
on 4 August 1883. In 1884 Bruce received his first overseas commission to Malta, and accompanied by his wife he travelled to Valletta, where he took up post as resident medical officer at the Station
Hospital. At this time the naval and military hospitals at Malta contained large numbers of cases of an obscure continued fever with a high mortality rate; even in milder cases it was associated with
prolonged ill health and disability. So seriously was the incidence of this disease regarded that the naval and military medical officers were already collecting information on the clinical nature
and epidemiology of the disease. Bruce worked on its pathological and bacteriological aspects. Bacteriology was then in its infancy and the introduction by Robert Koch in 1880 of solid media and
other technical methods of isolating organisms, and the recent identification of the organisms of typhoid fever, respiratory tuberculosis, and cholera, directed Bruce to investigate the aetiology of
Malta fever using the new laboratory methods. Within two years he had found in the spleens of fatal cases an organism which he named Micrococcus melitensis
, later known as Brucella
. His research proved conclusively that this was the cause of Malta fever (brucellosis).
In 1888 Bruce left Malta on leave and worked with his wife in Koch's laboratory in Berlin. On his return to England he was appointed assistant professor of pathology at the Army Medical School at
Netley. In his five years here from 1889 to 1894, he introduced courses in bacteriology and improved the teaching of pathology. He was disappointed not to be made full
professor when, in 1892, a civilian, Almroth Wright, was brought in to fill the vacant post.
In 1894 Bruce was posted overseas again, this time to Pietermaritzburg in Natal, South Africa. In Zululand at this time a fatal disease, known as nagana or tsetse-fly disease, was devastating the
domestic animals of the native population and settlers. The governor of the colony, Sir Walter Hely-Hutchinson, who had been lieutenant-governor of Malta at the time of Bruce's successful work on
Malta fever, had Bruce seconded to investigate the disease. Within two months Bruce reported the discovery of a single-celled parasite, later named Trypanosoma brucei
, in the blood of
infected animals, and that this was the cause of both tsetse-fly disease and nagana, then thought to be two distinct diseases. In December 1896 he was seconded for a further period. He and his wife
spent two years in an isolated camp in the bush at Ubombo in Zululand. They lived and worked in wattle and daub huts and ate wild game which they themselves shot. By the end of this period they had
established the main facts regarding trypanosomiasis in domestic and wild animals and its transmission by the tsetse-fly. This confirmed Bruce's reputation as a scientist of remarkable capacity, and
while still absent in South Africa he was elected a fellow of the Royal Society (1899). In the South African War in 1899 the Bruces were caught in the siege of Ladysmith. Bruce had charge of a large
military hospital and acted as an operating surgeon, while his wife assisted him as sister in charge of the operating theatre. Following the relief of Ladysmith (in March 1900) Bruce was made a
member of the committee investigating typhoid and dysentery in the field, as these diseases were decimating the troops.
In 1901 Bruce returned to England and was appointed to the advisory board of the Army Medical Services department at the War Office. In February 1903 he was seconded to supervise the Royal Society's
sleeping sickness commission in Uganda. Sleeping sickness had reached epidemic levels among the lake-shore population, and the commission had been dispatched to find its cause and mode of
transmission. As often happens, the actual discovery of the cause of sleeping sickness was not wholly attributable to any one individual, though it was Bruce's systematic research that first
established the nature and cause of this fatal infection. Trypanosomiasis in animals caused by T. brucei
does not affect man; however, J. E. Dutton, working in the Gambia, had seen parasites
in the blood of a case of fever which he recognized as a trypanosome and which in 1902 he named T. gambiense
. In 1903, shortly before Bruce's arrival, Aldo Castellani, an existing member of
the commission, had found trypanosomes in the cerebrospinal fluid of five out of fifteen cases of sleeping sickness. He had disregarded this in favour of a bacterium he had also isolated. Castellani
told Bruce of his work and in the three weeks before he left for England found these organisms in twenty out of twenty-nine further cases. Bruce recognized the implications of Castellani's
observations and related this to his own experience with nagana. He collected information about the distribution of the disease and of tsetse-flies and set up fly-feeding experiments using the
Zululand research as a model. By August 1903, when the Bruces returned to England, he had established that sleeping sickness was also a trypanosome disease carried by the tsetse-fly and that it could
be transmitted from sick to healthy individuals by the bite of this insect.
Bruce's career now followed the path of a roving researcher, heading a series of successful investigations, until the outbreak of war in 1914. Thus in 1904 he revisited Malta, in charge of the Royal
Society's Mediterranean fever commission. Themistocles Zammit, a Maltese member of the commission, then identified the source of infection in Malta fever as the goat, transmission occurring when
contaminated milk was consumed. In 1908 Bruce visited Uganda as director of the third sleeping sickness commission, and in 1911 he led a further commission to Nyasaland to investigate human
trypanosomiasis. With the outbreak of war in 1914 Bruce was appointed commandant of the Royal Army Medical College, Millbank. He had held the rank of surgeon-general since 1912 after a special
promotion in recognition of his scientific work. He chaired the War Office pathological committee, and supervised those investigating tetanus and trench fever. He retired in 1919 on completion of the
written reports. Following his retirement he served as chair of the governing body of the Lister Institute. For reasons of health he spent the winters in Madeira, though he continued to keep in touch
with research at home and to give to workers the benefit of his experience and advice.
In all his work Bruce was assisted by his wife, who accompanied him throughout his foreign service, working in the laboratory and taking charge of camp arrangements. Immediately before his own death,
four days after his wife's, Bruce expressed the wish that her role in his scientific work should be recognized. She had been honoured with the Royal Red Cross for her work with the wounded in the
siege of Ladysmith, and was appointed OBE for her work for the committees on trench fever and tetanus during the First World War.
Among Bruce's many honours were a royal medal from the Royal Society in 1904 and its Buchanan medal in 1922. In 1923 Bruce was presented with the Albert medal of the Royal Society of Arts. From his
peers in the field of tropical medicine he received the Mary Kingsley medal from the Liverpool School of Tropical Medicine in 1905, the Leeuwenhoek medal of the Dutch Academy of Sciences in 1915, and
the Manson medal of the Royal Society of Tropical Medicine and Hygiene (of which he was president from 1917 to 1919). He was also awarded four honorary degrees and the membership of several foreign
academies and societies. He was Croonian lecturer of the Royal College of Physicians in 1915 and president of the British Association in 1924. He was appointed CB in 1905, and, having been knighted
in 1908, KCB in 1918.
Bruce was a man of strong physique and forceful mind. His research into the aetiology and transmission of animal and human trypanosomiasis helped to establish tropical medicine as a postgraduate
speciality in Britain. His approach to research problems was simple, logical, vigorous, and direct, and he had an intuitive perception of the essential point for attack. He contributed more than 172
scientific papers, of which thirty were co-authored by his wife. Bruce had a reputation for being reserved and self-contained, and Lady Bruce often smoothed the way for him. Among his contemporaries
he was renowned for his loyalty, and his integrity of mind and purpose. At the time of his death he was living at Artillery Mansions Hotel, Victoria Street, London. He died on 27 November 1931, at
Christchurch, Westminster, during the funeral of Lady Bruce, following a long period of ill health. He was cremated at Golders Green crematorium on 1 December.