426 Infectivity of Glossina morsitans in Nyasaland. 



This means that in experiments carried out in the manner described 

 T. brucei may be expected to turn up once in every three series, T. pecorum 

 eight times in ten, and T. simice and T. caprce six times in ten. 



Months and Seasons. 



On examining Table I it will be seen that these infective flies occur all 

 the year round, and are just as numerous during one season as another. It 

 will also be seen that no experiments on the infectivity of the flies were 

 carried out during July and August. This was due to the fact that all the 

 energy of the Commission was devoted during these two months to the study 

 of the wild game. 



Conchisions. 



1. The tsetse flies {Glossina morsitans) caught in the " fly-country " near 

 Kasu are infected with four species of disease-producing trypanosomes — 

 T. bmcei vel rhodesicnsc, T. pecorum, T. simice, and T. caprce. 



2. The proportion of infective flies is 13'5 per 1000. 



3. The proportion of flies infective with T. brucei vel rhodesiense, the cause 

 of the Human Trypanosome Disease of Nyasaland, is 2 per 1000. 



4. The flies are found infective all the year round. 



5. To prevent the infection of tsetse flies it is proposed that the experiment 

 should be tried of destroying all the wild game in the " Proclaimed Area " of 

 Nyasaland. 



