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Zululand.
Tse-tse Fly disease or Nagana.—Surgeon-Major D. Bruce, A. M. S., in a preliminary report published
in December 1895, defines the disease as " a specific one, which occurs in the horse, donkey, ox and dog
and varies in duration from a few days or weeks to many months. It is invariably fatal in the horse,
donkey and dog, but a small percentage of cattle recover. It is characterized by fever, infiltration of
coaguable lymph into the subcutaneous tissue of the neck, abdomen or extremities, giving rise to
swelling in these regions, by a more or less rapid destruction of the red blood corpuscles, extreme
imaciation, and the constant occurrence in the blood of an infusorial parasite, either identical with or
closely resembling the Trypanosoma. Evansi found in Surra, a disease of India and Burmah. On post-
mortem examination, deposition of a yellow jelly-like material in the subcutaneous tissue, inter-mus-
cular layers and under the serous covering of the heart, with purplish stains or ecchymosis in various
regions as on the inner aspect of the skin, the serous membrane covering the lungs, and the outer
and inner surfaces of the heart, enlargement and softening of the spleen and congestion and fatty
degeneration of the various organs."
Distribution in Zululand.—" Broadly it may be stated that the disease is limited to certain tracts,
the physical conditions of which imply heat and moisture. These tracts in Zululand are situated in
the level coast plain, which extends some 50 miles inland, and river valleys which enter or debouch on
this plain. From Ubombo, situated on the summit of one of the hills forming the chain of the
Lebombo mountains, a good view is obtained of this level coast plain, stretching from the base of the
mountain to the sea, some 60 miles off. It looks as level as a billiard table, and is covered as far as the
eye can reach to the north and south and merges in the blue of distance and of the sea to the
eastward. A few miles to the south, the river Imkasi can be seen winding across the plain, having
just passed through the Lebombo Range by a deep canon or poort, to fall into St. Lucia Lake, its course
being by the denser vegetation along its banks ; and some dozen miles to the north, another river, the
Pongola, runs out into the plain in the same manner, to turn northward to Delagoa Bay. The strip of
country opposite, lying between the two rivers and extending some 15 miles out, is 'fly country' the
home of Nagana and malaria and uninhabited except by wild animals."
" The evidence goes to show that the disease has existed in the lower tracts of the country, time
out of date, and is in no sense a new disease."
The first series of experiments instituted was, to find if flies kept in captivity at Ubombo would
cause any local or general disease in susceptible animals. Result negative. The next series was devised
in order to prove whether the Tse-tse fly can or cannot carry the disease from an affected animal to a
healthy one. Result positive. A healthy horse was taken on three days (19th. 24th, and 29th September)
into the fly-country, and remained there without being allowed to graze from 10 A.M. to 4 P.M. It was
noted that Tse-tse flies settled on him during the day. On October 4th on microscopical examination
of his blood he was found to be suffering from the fly disease.
That this parasite is the true cause of fly-disease is rendered almost certain from the following
considerations.
1. It is found in the blood of every animal suffering from this disease, and is absent from the
blood of all healthy horses, cattle or dogs.
2. The onset of the disease is marked by a rise of temperature, and this corresponds with the first
appearance of the hæmatozoa in the blood.
3. As the disease progresses pari passu with the destruction of the red blood corpuscles, the
parasites tend to become more numerous, sometimes reaching the enormous number of 6, 10, 15,
millions in every drop of blood.
4. The transference of the smallest quantity of blood from an affected to a healthy animal sets up
the disease in the latter, as even the very small quantity of blood conveyed by the proboscis of a few
tse-tse flies is sufficient to carry the disease from animal to animal.
The disease in cattle ' may be of a much slower and more chronic nature than in the horse or
the dog.' Cattle " gradually waste away, the hair at first harsh and staring tends to fall off, there
is the same trickling of a watery fluid from the eyes and nose and a tendency to diarrhœa. In many
cases the dewlap becomes swollen and boggy, but I have not found the same tendency to the
swelling of the under-surface of the belly or the extremities as in other animals, nor have I even seen
blindness occur in cattle. The hæmatozoa are also in my experience much less numerous in the blood of
cattle than in that of horses and dogs, and often require to be looked for on several days in succession
before they can be demonstrated."
In cattle, therefore, it would be rash to affirm that the disease from which they were suffering was
not Nagana until the blood had been subjected to daily microscopical examination for at least a week.
Tonquin (COCHIN-CHINA).
Blanchard * observed Surra amongst the mules imported into Tonquin (Cochin-China) for the use
of the French Army.
Blanchard. " Etude sur une Maladie Spéciale des Mulets Importés an Tonkin."
Bulletin, Soc. Centr. de Méd Veterinaire, 1888, page 694.