The Animal Parasites of Man

by Harold Benjamin Fantham; Max Braun; J. W. W. Stephens; Fred. V. Theobald

Sleeping sickness, due to Trypanosoma gambiense or varieties thereof, was first reported from West Africa and is now present, not only along the West Coast and in Nigeria, but throughout the Congo basin into Uganda, north of which it exists in the Bahr-el-Ghazal province of the Sudan. In Nyasaland and Rhodesia a more virulent but less widely distributed disease is produced by Trypanosoma rhodesiense.

There is a general similarity between the two diseases, and the symptoms as described by the leading authorities agree in the main. The malady due to T. rhodesiense has been known only since 1910 and the differences between the malady due to it and to T. gambiense will be indicated.

The course of the disease may be roughly divided into three stages, the incubation, the febrile or glandular, and the cerebral stage.

The exact incubation period is not known with certainty in man. Probably, in most cases, it does not exceed two to three weeks, but disease signs may not appear for months. The bite of the Glossina gives rise to local irritation, which may be overlooked. The irritation usually subsides in the course of a few days.

The febrile, or glandular stage, is marked by attacks of fever of an intermittent type. An erythematous eruption is often found on Europeans. This rash begins as irregularly shaped pinkish patches which clear in the centre until a ring is produced. It may occur on any part of the body but is more frequent on the trunk. A typical symptom is the enlargement of one or more of the lymphatic glands, especially those of the neck. A general, deep hyperæsthesia, known as Kerandel’s sign, may be present, and if the patient strikes a limb against any hard object, a feeling of acute pain is felt, the sensation being slightly delayed. As repeated attacks of fever increase, the patient may become anæmic. The febrile stage may last for years, and cure may be brought about at this phase, but frequently, after the febrile stage has lasted some time, the cerebral stage is reached. Tachycardia is also a symptom. Auto-agglutination of the red blood corpuscles is another useful characteristic, as it is said to occur rarely in other tropical diseases, but some workers doubt its value.

The cerebral, or true sleeping sickness stage is marked by a great change in the habits of the victim, who becomes apathetic and dull, careless and dirty in habits, and begins to experience difficulty in walking. Tremors of varying degrees of severity are common and the gait is peculiar. There is usually fever with rise of temperature from 100° F. to 104° F. in the evening, becoming subnormal in the morning. For some days before death, it often becomes permanently subnormal. Congestion and œdema of the lungs, with patches of pneumonia, are not infrequently observed before death. The torpor gradually deepens, and the patient loses flesh. Frequently the lips swell and saliva dribbles. The patient usually becomes comatose and death ensues. Mania and delusions, and psychical and physical symptoms resembling those found in general paralysis of the insane, sometimes occur, and death may arise from secondary complications such as pneumonia or dysentery.

Pathologically, the disease seems to consist of a chronic inflammation of the lymphatic system. The trypanosomes reach the lymphatic glands which become inflamed, and gradually invade the blood and the cerebrospinal fluid. Sooner or later, as a result of the lymphatic disease, changes occur in the membranes and substances of the brain and spinal cord. There is round-celled perivascular infiltration of the pia-arachnoid of the brain and spinal cord. These changes cause compression of the blood-vessels, and so lessen the supply of blood to the brain and spinal cord. Further changes in the latter organs result in the production of the symptoms that have given the disease the name of “sleeping sickness.”

The disease due to Trypanosoma rhodesiense generally runs a more rapid course than that due to T. gambiense. The torpor and sleepiness may not be obvious or be very slight, and the enlargement of the lymphatic glands of the neck also may not be marked or may appear to be absent. The duration of the disease often appears to be from three to six months.

Treatment is only of use if commenced in the earlier stages of the disease. The substances of most value so far are arsenic in the form of atoxyl (introduced by Wolferstan Thomas in 1905) and antimony in the form of tartar emetic. Castellani and Chalmers and Manson recommend treatment by combining the use of both substances. The combined treatment is recommended not only because both substances have been proved of service independently, but also because certain strains of trypanosomes resistant to arsenic are known, and trypanosomes can develop a resistance to arsenic. Such forms, that would not be affected by the atoxyl, are left open to attack by the antimony salt. Daniels also recommends combined arsenic and antimony treatment, and (1915) uses atoxyl and antiluetin.