The Period of Invasion.—After an incubation period which may be as short as ten or twelve days, following the bite of an infective tsetse fly, the trypanosomes may be found in the blood or in gland juice. One case has been reported where an official of the Belgian Congo showed trypanosomes less than four weeks after his arrival in the colony. His first symptoms were noted about ten days after his arrival.
In natives, trypanosomes may be present in the blood for long periods of time during which they may do heavy work; thus 7 of Koch’s 52 native porters showed trypanosomes. In Europeans however the course of the disease is rarely so insidious but rapidly enters upon the stage of trypanosome fever.
The Stage of Trypanosome Fever.—Although fever may be absent in natives until the onset of the period of sleeping sickness, yet in Europeans there are usually noted febrile paroxysms, lasting for a few days, and followed, by afebrile periods varying from a few days to two or three weeks.
The temperature curve is of a markedly remittent type, approaching normal in the morning and going up to 103°F. or higher in the evening—a wide daily range. Very characteristic is a low-tension rapid pulse which often is as rapid when the temperature approximates the normal as when it is higher. Early in the disease there are evidences of involvement of the nervous system, as shown by headache insomnia, difficulty of concentration for mental work and cardiac instability.
Fig. 30.—Rash of human trypanosomiasis. (Photo: R. McKay.) By permission from Manson’s Tropical Diseases.
Winterbottom Sign.—Very important are the glandular enlargements, particularly of the glands of the posterior cervical triangle (Winterbottom’s sign), which upon puncture may show trypanosomes when the blood examination fails to reveal them. The glands are discrete, soft, usually painless and may show but very slight enlargement. Oedematous swellings, especially about the eyes or joints or in localized areas upon the trunk, may be rather prominent in some cases. In Europeans pinkish erythematous rings appearing early in the infection may make one think of syphilis. These erythematous patches are not visible on the skin of natives. A dryness of the skin is rather constant and, especially in natives, papules which itch greatly may be present. Rarely such manifestations as orchitis or choroiditis may be observed.
Fig. 31.—Swelling of the glands of the posterior cervical triangle—Winterbottom’s sign. (Ruge and zur Verth after Koch.)
Kérandel Sign.—Recently great prominence has been given to a deep hyperaesthesia, which shows itself as a lively pain, often retarded, after some slight blow upon a bony projection of the body. Kérandel, who suffered from trypanosomiasis, noted that the fear of striking against objects became with him an absolute obsession. It is called the Kérandel sign. It is during this first stage, when the trypanosomes are to be found only in the blood or gland juice that the disease would appear to be curable. Upon the appearance of the trypanosomes in the cerebro-spinal fluid (second stage) we have practically a hopeless prognosis.