MAST1GOPHORA - 1089 



anopheles, mansonia and perhaps fleas, may act as mechanical carriers. 

 It is also possible that the disease is transmitted by coitus. Without 

 some such explanation it is difficult to understand certain house 

 epidemics which have occurred outside the fly belts. 



The animal host of the Trypanosoma gambiense is believed to be 

 the big game animals, particularly the antelope. 



FIG. 141. TSETSE FLY (GLOSSINA PALPALIS). (From Rosenau, " Preventive 



Medicine and Hygiene.") 



Morphology. The organism belongs to the brucei group, and its 

 differentiation on morphology is difficult, yet, on the average, the 

 posterior end is somewhat more pointed than the brucei. In length 

 it varies from fifteen to thirty microns, and in thickness from one to 

 three microns. In fresh preparations the motility is not marked; 

 both plump and slender forms are found in the blood, but in the cere- 

 bro-spinal fluid slender forms only are seen. 



Cultures on blood agar have been made by Thompson and Sinton, 

 yet they died out after a few weeks, and were never virulent. The 

 pathogenicity varies somewhat with the strain used, but apes are easily 

 infected. In white rats there may be two or three relapses before 

 death occurs, while when inoculated with brucei death follows within 

 two weeks. 



Pathogenicity. Although cultures vary greatly in virulence, it is 

 possible to infect rats, dogs arid monkeys with a fatal trypanosomiasis ; 

 cattle, sheep and goats continue to show a few parasites for months 



