MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 885 



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 their 

 reduced condition makes them especially liable. The symptoms are 

 due to damage done both by the mechanical presence of the parasites 

 and to a trypanotoxin produced by them. The parasites not only live 

 in the blood and other fluids of the body but are found in the tissues of 

 various organs. They are distributed throughout the tissue of the brain 

 and their presence is associated with infiltration of the peri-vascular 

 lymph spaces with large numbers of lymphocytes. 



The recognition of trypanosomiasis depends upon the demonstra- 

 tion of the parasites. They may be found in fresh or stained prepara- 

 tions 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 (1901-1911) 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. Inor- 

 ganic arsenic drives the parasites from the blood and improves the 

 patient's condition. Unfortunately, the trypanosomes usually reap- 

 pear and, then, they have become resistant to arsenic so that the 

 patient succumbs in spite of repeated doses. Many organic com- 

 pounds of arsenic were experimented with in the hope of finding an 

 efficient trypanocide and several valuable drugs have been found: 

 "Atoxyl" which is the sodium salt of para-amido-phenyl-arsenic acid, 

 acetylated atoxyl, and arsenophenylglycin, are all organic compounds 

 of arsenic. They are much more effective than is arsenic itself. 

 Similar organic compounds of antimony and tartar emetic are as 

 effective, while certain aniline dyes have a distinct trypanocidal value. 

 It has been found that trypanosomes may become resistant to any one 

 of these drugs, and that drugs may destroy some stages of the trypano- 

 some while they are unable to destroy others. In order to give the 

 parasites no opportunity of acquiring resistance to any drug, and in 

 order to destroy them at all stages of their development, the following 

 general rules are now observed in the treatment of trypanosomiasis. 

 The drugs employed should be alternated, and they should be given 



