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{{rh|X]|SLEEPING-SICKNESS STAGE| 173 Death from intercurrent disease, or from rapidly developing cerebral implication causing convulsion, the status epilepticus, coma, etc., may supervene at any stage of trypanosomiasis. Usually the case gradually drifts into the stage known as "sleeping sickness."*

Sleeping sickness.—— The condition known as sleeping sickness may be regarded as the terminal stage of trypanosoma infection. Sometimes it exhibits acute features, sometimes it is exceedingly chronic. From the commencement of the infection to the development of this terminal stage, in a proportion of instances an interval of many years, possibly seven, may elapse. In the majority of cases the march of events is much more rapid. The characteristic terminal symptoms depend on implication of the nervous system either by the parasite itself or by its toxins. According to Low and Castellani, the average duration of this stage of trypanosomiasis in the African is from four to eight months, not infrequently less; very chronic cases with a course of more than a year's duration are rare. Other observers refer to cases running on for three years, or even longer, and presenting occasionally temporary ameliorations. Generally the first indications of the oncoming of sleeping sickness are merely an accentuation of the debility and languor usually associated with trypanosoma infection. There is a disinclination to exertion; a slow, shuffling gait; a morose, vacant expression; a relaxation of features; a hanging of the lower lip; a puffiness and drooping of the eyelids; a tendency to lapse into sleep or a condition simulating sleep; a slowness in answering questions; a shirking of the day's task. Dull headache is generally present. Later there may occur fibrillary twitching of muscles, especially of the tongue, and tremor of the hands, more rarely of the legs, indicating a definite