Various species of Trypanosoma from the blood of mammals, birds, and reptiles. A. T. Lewisii, from the blood of rats; B. T. Brucei, the parasite of the Nagana or Tsetze-fly disease, found in the blood of horses, cattle, and big game; C. T. gambiense, the parasite causing Sleeping Sickness in man; D. T. equinum, which causes the mal de caderas in South American horse ranches; E. T. noctuæ, from the blood of the little owl, Athene noctua; F. T. avium, found in the blood of many birds; G. a species found in the blood of Indian pigeons; H. T. ziemanni, a second species from the blood of the little owl; J. T. damoniæ, from the blood of a tortoise; c.g., granules; v., vacuole; l.s., fold of the crest or undulating membrane.
These figures are from Dr. Woodcock’s article on the “Hæmoflagellates” in the Quarterly Journal of Microscopical Science, April and June, 1906. (See also the figures in the [next chapter] relating to Sleeping Sickness.)
The Trypanosomes have acquired a terrible notoriety within the last four years, since another species, also carried by a Tsetze fly of another species, has been discovered by Castellani in cases of Sleeping Sickness in Uganda, and demonstrated by Colonel Bruce to be the cause of that awful disease.[21] Over 200,000 natives of Uganda have died from it within the last five years. It is incurable, and, sad to relate, not only a certain number of European employés have succumbed to it in tropical Africa, but a brave young officer of the Army Medical Corps, Lieutenant Tulloch, has died from the disease acquired by him in the course of an investigation of this disease and its possible cure, which he was carrying out, in association with other men of science, on the Victoria Nyanza Lake in Central Africa. Lieutenant Tulloch was sent out to this investigation by the Royal Society of London, and I will venture to ask my readers to join that body in sympathy for his friends, and admiration for him and the other courageous men who risk their lives in the endeavour to arrest disease.
Trypanosomes are now being recognised in the most diverse regions of the world as the cause of disease—new horse diseases in South America, in North Africa, in the Philippines and East India are all traced to peculiar species of Trypanosome. Other allied forms are responsible for Delhi-sore, and certain peculiar Indian fevers of man. A peculiar and ultra-minute parasite of the blood cells causes Texas fever, and various African fevers deadly to cattle. In all these cases, as also in that of plague, the knowledge of the carrier of the disease, often a tick or acarid—in that of plague the flea of the rat—is extremely important, as well as the knowledge of reservoir-hosts when such exist.
The zoologist thus comes into closer touch than ever with the profession of medicine, and the time has arrived when the professional students of disease fully admit that they must bring to their great and hopeful task of abolishing the diseases of man the fullest aid from every branch of biological science. I need not say how great is the contentment of those who have long worked at apparently useless branches of science—such as are the careful and elaborate distinction of every separate kind of animal and the life-history and structure peculiar to each—in the belief that all knowledge is good, to find that the science they have cultivated has become suddenly and urgently of the highest practical value.
I have not time to do more than mention here the effort that is being made by combined international research and co-operation to push further in our knowledge of phthisis and of cancer, with a view to their destruction. It is only since our last meeting at York that the parasite of Phthisis or Tubercle has been made known; we may hope that it will not be long before we have similar knowledge as to Cancer. Only eighteen months have elapsed since Fritz Schaudinn discovered the long-sought parasitic germ of Syphilis, the Spirochæta pallida (see [fig. 6]). As I write these words the sad news of Schaudinn’s death at the age of thirty-five comes to me from his family at Hamburg—an irreparable loss.
Let me finally state, in relation to this study of disease, what is the simple fact—namely, that if the people of Britain wish to make an end of infective and other diseases they must take every possible means to discover capable investigators, and employ them for this purpose. To do this, far more money is required than is at present spent in that direction. It is necessary, if we are to do our utmost, to spend a thousand pounds of public money on this task where we now spend one pound. It would be reasonable and wise to expend ten million pounds a year of our revenues on the investigation and attempt to destroy disease. Actually what is so spent is a mere nothing, a few thousands a year. Meanwhile our people are dying by thousands of preventable disease.