TRYPANOSOMIASIS 



133 



The bite of an infected mosquito does not become infectious 

 until twelve days after it has bitten the first patient. 

 There is a definite time between the bite of the mosquito 

 and the infectivity of the patient's blood (average five 

 days), and a definite time the blood remains infective 

 (three days). The blood during these three days is still 

 infective after passing through the finest-grained porcelain 

 filters. (See page 126.) 



Competent authorities incline to the belief that the 

 organism of yellow fever is a protozoon, i. e., a unicellular 

 animal micro-organism. 



TRYPANOSOMIASIS 



In connection with malaria and yellow fever a word 

 may be said about trypanosomiasis or "sleeping-sickness." 

 This dreaded African scourge is caused by a protozoon 

 somewhat similar to that of malaria, and transmitted not 

 by the mosquito, but by a species of biting-fly, known as 

 the ''tsetse fly." The characteristic symptoms are pro- 

 duced by the trypanosomes entering and growing in the 

 cerebrospinal fluid. The disease appears to be almost in- 

 variably fatal. 



