Giovanni Martinaglia, the first European baby born in Roodepoort, obtained a BSc degree from the University of Toronto, Canada, in 1919. The next year he was awarded an MSc degree from Cornell University, United States, for a thesis on The direct isolation and cultivation of human, bovine and avian tubercle bacilli. During 1921 he was employed by the Rockefeller Institute and from 1921 to 1922 by the Johns Hopkins Medical School in Baltimore as demonstrator in pathology. During this time he also visited Jamaica to study leprosy. He then returned to South Africa and obtained his BVSc degree at the Veterinary Faculty of the Transvaal University College at Onderstepoort in 1924. He served as veterinary research officer at the Allerton Laboratory in Natal until 1926, when he was transferred to Onderstepoort. There he worked with P.R. Viljoen* on parathyroid disease in calves from the Marico District, the main cause of which proved to be a paratyphoid infection of the Salmonella type. An early report on this work, "The occurrence of Paratyphoid, Bacillus enteritidis, infection in calves in South Africa", was published in the South African Journal of Science (1926, Vol. 23, pp. 532-545). In 1929 Marinaglia reported extensively on his work on five types of Salmonella infections that he had encountered in domesticated animals and birds in South Africa. This work was written up also in the form of a thesis, Diseases of domesticated animals in South Africa due to organisms of the sammonella group, for which he was awarded the DVSc degree by the University of Toronto, Canada. That same year he and R. Paine* published a paper on cases of tuberculosis in South African kudus and duikers in the Journal of Comparative Pathology. In May 1930 Martinaglia was appointed municipal veterinarian to the Johannesburg abattoir, of which he later became director.
As a young boy Martinaglia was one of the first persons to see the Sterkfontein Caves, which were blasted open by his father, Guglielmo Martinaglia, around the beginning of 1897. After he had settled in Johannesburg he visited the caves again in 1933 and became the first to investigate some aspects of their biology. He submitted two fly species collected in the caves to the Imperial Institute of Entomology for identification; one of these proved new to the collections of the British Museum (Natural History). He also collected mites from bats, which were sent to the British Museum.
After his retirement in 1948 he undertook research on tuberculosis at the King George V Hospital, Durban, for a further 15 years. He was survived by his wife, Violet Iris Martinaglia, and three children.