678 MICROBIOLOGY OF THE DISEASES OF MAN AND ANIMALS. 



multiply in other ways, as do other trypanosomes; for example, a trypanosome of 

 frogs loses its locomotory apparatus and forms a sphere, then the sphere divides into 

 many small spheres, each of which becomes a trypanosome. Sometimes Trypanosoma 

 gambiense loses its locomotory apparatus and forms a sphere ; these forms are found in 

 the organs of infected animals. They are probably more resistant, resting forms and 

 a single trypanosome may be formed from some of them. 



Tryanosomiasis is easily transmitted to susceptible animals by inoculation. It is 

 possible that the disease may be transmitted occasionally, in this way, by the mere 

 mechanical exchange of infected material, through an insect's bite, from an infected to a 

 healthy individual. But, as a rule, the disease can only be transmitted by the bites of 

 Glossina palpalis (Fig 125); this fly is not infective until three weeks after it has fed on 

 an infected person, and it retains its infecting power for some months. 



An incubation period of at least ten days intervenes between the bite 

 and the appearance of symptoms; the incubation period may be much 

 longer, for trypanosomiasis may manifest itself in apparently healthy 

 negroes several years after they have left any locality in which the disease 

 could have been acquired. The disease sometimes causes death within 

 three or four months; but it may last for one or more years. It is a chronic, 

 wasting affection, characterized by loss of strength and energy, and by an 

 irregular fever. A change in the character, red blotches on the skin, and 

 enlargement of the lymphatic glands are all early signs of the disease. In 

 the later stages, headache, mania, uncontrollable sleep, and other nervous 

 symptoms may be present. Death rarely results from trypanosomiasis 

 alone; the patients usually succumb to one of the secondary infections, 

 to which the reduced condition of cases of sleeping sickness makes them 

 especially liable. Although no toxin has been isolated, most of the 

 symptoms are probably due to one, produced by the trypanosomes. 



The recognition of trypanosomiasis depends upon the demonstration 

 of the parasites. They may be found in fresh or stained preparations of 

 the blood, in the juice obtained by aspirating an enlarged lymphatic gland, 

 or in the cerebrospinal fluid. The examination of the blood is the simplest 

 method of searching for trypanosomes; the examination of gland juice is 

 the most efficient one. 



The improvement in the methods of treating trypanosomiasis during 

 the past ten years (1910-1911) affords an excellent example of the value 

 of laboratory work. Before 1901 arsenic, given in some inorganic form, 

 was the only drug known to have any effect on trypanosomiasis. In- 

 organic arsenic drives the parasites from the blood and improves the 

 patient's condition. Unfortunately, the trypanosomes usually reappear 



