Preliminary report on the tsetse fly disease or nagana, in Zululand / By Surgeon-Major David Bruce.
- Bruce, David, Sir, 1855-1931?UNAUTHORIZED.
- Date:
- 1895
Licence: Public Domain Mark
Credit: Preliminary report on the tsetse fly disease or nagana, in Zululand / By Surgeon-Major David Bruce. Source: Wellcome Collection.
Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.
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![angle to them the proboscis, by which it pierces the skin and sucks up the blood. The proboscis is formed of several pieces, some acting and looking like narrow knife blades, others acting as a tube to contain the blood. On placing the proboscis under the microscope this tube can be readily seen lying alongside the knives, and lined with large epithelial cells, some of which are developed into hair-like processes or cilia, by the movement of which I presume the blood is conveyed to the oesophagus of the Fly. At the base of the proboscis is a relatively large brown or yellow coloured gland, from which a clear fluid can be expressed, which, on being dried, deposits very beautiful fern-like crystals. This is probably the fluid which the Fly injects into its victim and which sets up the well-known irritation and swelling. From the mouth a straight thin tube or oesophagus leads to the stomach, which, of course, is situated in the abdominal part of the insect. The stomach when dilated with blood is about the size of a buck shot, and bright red in colour. The blood inside is always coagulated into a firm red-currant jelly-like mass, and does not change its colour until it reaches the intestine. The intestine is a blackish coloured tube, which passes from the stomach to the vent. It does not contain many blood corpuscles, but merely minute round shining crystalline bodies, the product of the disintegration of the red blood corpuscles. This description of the anatomy of the Tsetse is only meant to describe broadly its pronounced features. The proboscis itself is a most complicated piece of apparatus, and would require a paper as long as this Report to describe it fully. The result of my examination up to the present of the Tsetse Fly is briefly this .— Immediately after feeding, the tube of the proboscis can be seen to be crammed lull of red blood corpuscles, among which the lmematozoa can be seen actively wriggling. Up to 46 hours after feeding I have seen living heematozoa and red blood corpuscles in the proboscis. After 118 hours the hasmatozoa are still very numerous and vigorously active in what remains of the blood in the stomach. After 140 hours the stomach is empty. After 25 and 70 hours I have seen many motionless hsematozoa in the faeces, but I have never seen at any time any appearance of life in the hamiatozoa in the fasces or contents of the lower part of the intestine. The parasites appeared, however, unchanged in form, and I intend making some injection experiments with the fa?ces to find out if these motionless hajmatozoa have any vitality left in them. B.—RELATION OF BIG GAME TO THE FLY DISEASE. As we have found that the Tsetse Fly in a state of nature does act as a carrier of (lie haunatozoon of Fly Disease, it is evident that it must procure the parasite somewhere, and what more natural than that it should procure it from the blood of warm blooded animals living in the Fly Country ? It is not necessary to suppose that in these animals Nagana is a fatal disease, but only that the big game harbour the parasite which causes the disease for a longer or shorter time with little or no disturbance to health. We have seen, as in the case of the heifer mentioned on page 33, that cattle may have the parasite in their blood for at least 18 months without causing death, and it is possible that some of the big game die of this disease. When in the Fly Country quite lately I chanced on a dead wildebeeste surrounded by vultures. The skin of this animal was quite intact and showed no signs of its having come to a violent death. It was somewhat emaciated and had the appearance of an animal dead of Nagana. I did not inject any blood from it into a susceptible animal, as it was in a state of decomposition. According to Lingard two species of rat (Mus decumanus and Mus rufescens) in India harbour the Surra parasite often in large numbers without appearing to produce any noticeable symptoms in the great majority of them, although some few rats appear to succumb to the disease. Lingard examined 1,107 rats for the hamiatozoon and found it present in 421, absent (58(5. He also made experiments on animals with the hasmatozoon of the rat, and as this has an important bearing on the subject of the relation of big game to the Fly Disease, I shall give his account in his own words. Dr. Lingard states (page 4. Summary of Further Report on Surra. 1894) :— Proof was wanting that this ha?matozoon was capable of producing Surra, when blood containing the organism was subcutaneously injected into horses and some other species of animals. As early as November, ] 890, I commenced a series of experiments for the purpose of deciding the above question, and obtained positive results, but found that the periods of incubation were more prolonged than in Horse-Surra, in one case being as much as t>3 days. Notwithstanding this, the virulence of the disease when once developed was intense, as shown by the short period during which the animal survived after tiie appearance of the hneniatozoon in the blood : this being in three cases only 2 to 5 days. D 2](https://iiif.wellcomecollection.org/image/b21364655_0087.jp2/full/800%2C/0/default.jpg)
