302 
both  Lake  Mweru  and  Tanganyika,  the  most  heavily  infected  villages 
were  those  directly  contiguous  to  the  Congo  Free  State.  1  he  further 
extension  of  the  disease  has  been  aided  by  the  free  communication, 
chiefly  in  canoes,  which  has  been  going  on  from  village  to  village. 
Although  there  has  been  free  communication  with  German  East 
Africa,  it  is  rather  improbable  that  many  of  the  cases  were  contracted 
there,  as  the  disease  was  introduced  into  that  country  (i.e.,  the 
eastern  shores  of  Tanganyika)  from  the  Congo  Free  State""  about  the 
same  time  that  it  was,  in  all  probability,  introduced  into  Rhodesia, 
that  is  to  say,  not  later  than  1905.  Comparatively  few  cases  have 
been  reported  from  the  Bismarckburg  section  of  German  East  Africa, 
which  is  the  portion  bounding  North-Eastern  Rhodesia. 
•Since  its  introduction  into  British  territory,  it  has  almost  assumed 
endemic  proportions  on  Lake  Tanganyika.  In  Novembei,  1907, 
twelve  cases  were  found  ;  in  June,  1908,  sixteen  additional  ones  ;  and 
others  since  then ;  so  that  there  is  (or  was,  as  they  have  since  been 
moved)  hardly  a  village  on  the  lake  shore  in  which  one  or  more 
infected  natives  has  not  lived. 
We  have  seen  enough  on  this  lake  to  make  us  realise  very  fully 
the  great  importance  of  international  co-operation  in  dealing  with 
Sleeping  Sickness.  However  good  a  system  of  fighting  the  disease 
may  exist  in  any  one  country,  its  efforts  are  sure  to  be  retarded  if  the 
neighbouring  territories  remain  apathetic.  When  the  authorities  in 
Rhodesia  commenced  to  isolate  the  infected,  some  of  them,  and  in 
one  or  two  cases  whole  villages,  immediately  decamped  over  the 
border,  where  they  not  only  constituted  a  source  of  danger  to  then- 
new  country,  but  remained  one  10  that  which  they  had  left,  for  the 
probability  existed  that  they  would  find  their  way  back  to  their  old 
villages  as  soon  as  they  thought  the  vigilance  of  the  authorities  had 
relaxed. 
IX.  PROPHYLAXIS 
From  the  reports  published  in  various  parts  of  Africa  it  is  quite 
evident  that  it  is  useless  to  attempt  to  advance  a  system  of  prophy¬ 
laxis  which  will  apply  equally  well  to  every  country.  Certain  well- 
defined  methods  of  procedure  exist,  but  so  many  factors  have  to  be 
Colonial  reports.  German  Last  Africa,  for  the  year  1905-^.  No  cases 
Sleeping  Sickness  had  been  found  in  the  Bismarckburg  section  at  this  date. 
