Leonard Rogers, one of the numerous children of Captain Henry Rogers, R.N., of Hartley House, Helston, Cornwall, was born near Plymouth. His mother was Jane Enys, of Enys, Penryn. Through her he was descended from Davies Gilbert, mathematician president of the Royal Society from 1825 to 1829.
Rogers was educated at Tavistock Grammar School, where he showed notable mathematical ability, Plymouth College, and St. Mary’s Hospital, London. For most of his life he was engaged in medical research, beginning as a student before qualification. After a few hospital appointments he decided that a career in pathology could be achieved in the Indian Medical Service, and he entered that Service by competition in 1893. At first he was posted to the military branch, in which he began to investigate problems of malaria and the clotting of blood. The quality he showed in this work led to his appointment to investigate kala-azar in Assam, where it was epidemic. He was not able to differentiate this disease from malaria with the facilities at his disposal, but he did appreciate the fact that it was a disease strongly associated with certain places, and he devised an effective method of prevention by moving the occupants of affected villages to new sites.
In 1900 he was appointed professor of pathology in Calcutta. There he disentangled the aetiology of dysentery to the extent of recognising entamoeba histolytica as a cause of this and of liver abscess, and showed that repeated aspiration of liver abscess was a safer treatment than the open operation formerly practised. At that time ipecacuanha had some reputation in the treatment of dysentery, but it had troublesome side effects, and Rogers, learning that its active component, emetine, had an action on non-pathogenic water amoebae, tried it in amoebic dysentery with great success. It remains the basis of the most favoured treatment to the present time. Similarly, having heard that salts of antimony had been used in African trypanosomiasis, and arguing that the parasites of leishmaniasis were protozoa in some respects akin to trypanosomes, he tried antimony in kala-azar, again with conspicuous and lasting success.
Cholera was the great epidemic disease of India, and it carried a high mortality. Rogers knew that replacement therapy with intravenous physiological saline was only moderately successful, and he therefore doubled the salt content in the hope that this would, perhaps by osmotic action, prevent excessive loss of fluid. The results were good, and with modifications a similar procedure has proved its value.
Chaulmoogra oil had at that time some reputation for leprosy, but it was difficult to administer. Rogers therefore isolated from it an active fraction, sodium gynocardate, which could be given more easily and which, with modifications, remained the standard treatment until the sulphones were introduced during the Second World War.
These were major advances in treatment, though officially Rogers was a pathologist rather than a clinician. He was not, however, content with therapy. He realised that the true answer to the great epidemics of cholera which ravaged India periodically lay in prevention. These epidemics were closely associated with the great pilgrimages to various holy places, where multitudes of people gathered to bathe in, and drink, the sacred waters of the famous rivers. Rogers constantly advocated the compulsory immunisation of all pilgrims to these gatherings, but there were difficulties on religious grounds while the British were in power. However, the principle was adopted tentatively before the British left, and wholeheartedly by the Indian Government after that time, with the result that the epidemics have been dramatically reduced.
Rogers conducted research on snake venoms, the trypanosomiasis of horses, and other subjects, but he maintained an acute interest in the epidemiology of all the diseases encountered in India. He promoted the teaching of tropical medicine by collecting funds for the School of Tropical Medicine in Calcutta, which remains as a monument to his energy.
After retirement in 1920 Rogers was appointed medical adviser to the Secretary of State for India, physician to the Hospital for Tropical Diseases in London, and lecturer at the London School of Tropical Medicine; much of his energy in his later years was devoted to the work of the British Empire Leprosy Relief Association, for which he raised large sums of money, and to which he contributed the driving force of his own personality and much of his own money. He was elected president of the Royal Society of Tropical Medicine and Hygiene for the period 1933-5. At the College he delivered the Milroy (1907) and Croonian lectures (1924); he was awarded the Moxon medal in 1924 and was a Councillor, 1925-7. He received honorary degrees from the Universities of Glasgow and St. Andrews.
Throughout his life Rogers was completely absorbed in his work, and apart from cycling and walking he had no hobbies. He was the most frugal of men. He had a strong personality, and though he never deliberately cultivated the attitude of a great man he had about him a quality of authority which held the respect and affection of his colleagues.
He wrote extensively, always in the simplest and most direct language, without any attempt at literary elegance, but with a phenomenal grasp of mathematical method. After he retired he published an autobiography entitled Happy toil, which sufficiently expressed his life-long enthusiasm for research, and his faith in Christianity. It also expressed, to some degree, his great sense of fun, which otherwise bubbled to the surface in caustic comments on people he thought stupid. He was slight and wiry in build, with a thick head of stiff hair, white in later life, and a large military moustache.
In 1914 he married Una Elsie, daughter of C. N. McIntyre North, an architect in London. They had three sons, one of whom became a mathematician and a fellow of the Royal Society.
Richard R Trail
[Biogr.Mem.Roy.Soc., 1963, 9, 261-82 (p), bibl.; Brit.med.J., 1962, 2, 862-3 (p), 932, 1200; Bull. Calcutta Sch. trop. Med., 1962, 10, 174-5; Lancet, 1962, 2, 666-7 (p); Nature (Lond.)., 1962, 196, 517-18; St. Mary’s Hosp. Gaz., 1962, 68, 268-9 (p); Times, 20 (p), 22, 26 Sept. 1962; West Briton, Truro, 20 Sept. 1962; Sir L. Rogers. Happy toil: an autobiography. London, 1950(p).]