﻿ENTOMOLOGICAL 
  ASPECTS 
  OF 
  AN 
  OUTBREAK 
  OF 
  SLEEPING 
  SICKNESS. 
  351 
  

  

  be 
  accompanied 
  by 
  occasional 
  cases* 
  which, 
  as 
  the 
  potential 
  first 
  cases 
  in 
  a 
  possible 
  

   epidemic 
  and 
  for 
  the 
  cause 
  referred 
  to 
  on 
  p. 
  345, 
  would 
  be 
  particularly 
  virulent 
  

   individually. 
  

  

  The 
  presence 
  of 
  game 
  would 
  thus 
  be 
  protective 
  to 
  man. 
  It 
  was 
  impossible 
  to 
  

   resist 
  this 
  conclusion 
  when, 
  in 
  and 
  north 
  of 
  Nasa, 
  I 
  obtained 
  my 
  final 
  information 
  

   and 
  evidence 
  on 
  the 
  distribution 
  and 
  movements 
  of 
  the 
  game 
  and 
  a 
  continuance 
  

   of 
  the 
  striking 
  evidence 
  that 
  was 
  being 
  afforded 
  by 
  the 
  fly 
  itself. 
  I 
  had 
  already 
  

   seen 
  G. 
  morsitans 
  concentrate 
  on 
  man 
  during 
  very 
  temporary 
  absences 
  of 
  game, 
  

   but 
  the 
  Usukuma 
  evidence 
  suggested 
  a 
  next 
  step, 
  that, 
  in 
  relation 
  to 
  a 
  fly 
  closely 
  

   allied 
  to 
  G. 
  morsitans, 
  man 
  is 
  capable 
  of 
  replacing 
  the 
  destroyed 
  game 
  as 
  a 
  main 
  

   source 
  of 
  food-supply 
  ; 
  and 
  further, 
  that 
  such 
  a 
  position 
  may, 
  in 
  point 
  of 
  fact, 
  lead 
  

   to 
  an 
  epidemic 
  of 
  sleeping 
  sickness. 
  On 
  propounding 
  this 
  conclusion 
  (as 
  to 
  the 
  

   utility 
  of 
  the 
  game) 
  in 
  Entebbe, 
  I 
  was 
  most 
  interested 
  to 
  hear 
  from 
  Dr. 
  Duke 
  that 
  

   he 
  had 
  arrived 
  at 
  the 
  same 
  view 
  as 
  a 
  result 
  of 
  observations 
  in 
  Uganda 
  and 
  had 
  

   published 
  it 
  in 
  a 
  number 
  of 
  " 
  The 
  Field 
  " 
  which 
  I 
  had 
  not 
  seen. 
  I 
  am 
  glad 
  to 
  have 
  

   been 
  able 
  to 
  confirm 
  his 
  view, 
  and 
  I 
  think 
  it 
  is 
  of 
  particular 
  interest 
  that 
  the 
  conclusion 
  

   should 
  have 
  been 
  reached 
  in 
  relation 
  to 
  two 
  very 
  different 
  tsetse-flies, 
  two 
  very 
  

   different 
  game 
  faunas, 
  two 
  native 
  populations 
  with 
  quite 
  different 
  habits 
  — 
  one 
  of 
  

   lake 
  fishermen, 
  the 
  other 
  of 
  people 
  with 
  inland 
  pursuits 
  — 
  probably 
  two 
  different 
  

   trypanosomes, 
  and 
  from 
  the 
  two 
  different 
  standpoints 
  of 
  protozoology 
  and 
  entomology. 
  

  

  XX. 
  — 
  Possibilities 
  of 
  Spread. 
  

  

  Both 
  the 
  details 
  of 
  the 
  spread 
  of 
  the 
  Usukuma 
  outbreak 
  and 
  those 
  I 
  have 
  quoted 
  

   as 
  recorded 
  by 
  Taute 
  suggest 
  that 
  sleeping 
  sickness, 
  once 
  set 
  going, 
  is 
  capable, 
  

   through 
  the 
  agency 
  of 
  human 
  beings 
  who 
  travel 
  or 
  are 
  visited 
  in 
  the 
  presence 
  of 
  tsetse, 
  

   of 
  spreading 
  and 
  reproducing 
  itself 
  in 
  places 
  and 
  under 
  conditions 
  in 
  which 
  the 
  fly 
  

   is 
  paying 
  special 
  attention 
  toman, 
  but 
  in 
  which, 
  nevertheless, 
  the 
  disease 
  had 
  never 
  

   been 
  able 
  to 
  make 
  a 
  first 
  start 
  while 
  it 
  lacked 
  this 
  special 
  infection 
  by 
  man. 
  Further, 
  

   the 
  Kilwa 
  water-hole 
  focus, 
  infected 
  (it 
  seemed 
  certain) 
  by 
  the 
  travelling 
  Yaos, 
  was, 
  

   as 
  Taute 
  states, 
  not 
  less 
  than 
  150 
  miles 
  from 
  the 
  infection 
  on 
  the 
  Rovuma 
  and 
  

   much 
  further 
  from 
  what 
  was 
  regarded 
  by 
  the 
  German 
  workers 
  on 
  the 
  Rovuma 
  as 
  

   the 
  original 
  source 
  of 
  that 
  infection 
  — 
  namely, 
  Mwembe 
  or 
  Kumtmbe, 
  a 
  thickly 
  

   populated 
  area 
  of 
  the 
  Lujenda 
  valley. 
  It 
  becomes, 
  therefore, 
  of 
  the 
  utmost 
  importance 
  

   to 
  study 
  the 
  larger 
  movements 
  of 
  the 
  natives 
  with 
  a 
  view 
  to 
  their 
  judicious 
  control, 
  

   and 
  to 
  carry 
  out 
  a 
  most 
  thorough 
  search 
  for 
  sleeping 
  sickness 
  through 
  the 
  west 
  and 
  

   south 
  of 
  the 
  territory. 
  

  

  It 
  is 
  certain 
  that 
  we 
  cannot 
  know 
  the 
  position 
  to-day 
  as 
  regards 
  the 
  distribution 
  

   of 
  infection. 
  In 
  view 
  (1) 
  of 
  the 
  Belgian 
  occupation 
  of 
  the 
  west 
  of 
  the 
  country 
  during 
  

   and 
  since 
  the 
  war, 
  with 
  its 
  recorded 
  introduction 
  of 
  infects 
  and 
  its 
  alleged 
  exceptional 
  

   destruction 
  of 
  game 
  ; 
  (2) 
  of 
  the 
  fact 
  that 
  traffic 
  exists 
  between 
  the 
  infected 
  Usukuma 
  

   area 
  and 
  Uzinza, 
  the 
  fly 
  belt 
  south 
  of 
  Eyasi 
  and 
  elsewhere 
  ; 
  (3) 
  of 
  the 
  fact 
  that 
  foci 
  

   of 
  T. 
  gambiense 
  infection 
  existed 
  in 
  the 
  territory 
  itself 
  till 
  fairly 
  shortly 
  before 
  the 
  

   war, 
  and 
  of 
  T. 
  rhodesiense 
  still 
  later 
  ; 
  (4) 
  of 
  the 
  general 
  movements 
  of 
  men 
  in 
  the 
  war, 
  

   and 
  (5) 
  of 
  the 
  fact 
  that 
  Usukuma 
  was 
  not 
  the 
  only 
  area 
  which 
  suffered 
  during 
  the 
  

   war 
  from 
  famine, 
  heavy 
  porterage 
  and 
  game 
  disturbance 
  and 
  destruction 
  such 
  as 
  

   might 
  conduce 
  to 
  heightening 
  of 
  virulence 
  in 
  any 
  appropriate 
  trypanosomes 
  present 
  ; 
  

   it 
  will 
  be 
  surprising 
  if 
  we 
  do 
  not 
  find 
  foci 
  of 
  sleeping 
  sickness 
  of 
  one 
  or 
  other 
  

   kind 
  existing 
  to-day 
  in 
  the 
  great 
  Brachystegia 
  belts, 
  infested 
  with 
  tsetse, 
  that 
  extend 
  

  

  * 
  With 
  a 
  trypanosome 
  pathogenic 
  to 
  man 
  already 
  present, 
  any 
  bite 
  from 
  a 
  fly 
  which 
  had 
  

   shortly 
  beforebitten 
  an 
  infected 
  person 
  and 
  picked 
  up 
  trypanosomes 
  might 
  be 
  expected 
  to 
  be 
  capable 
  

   of 
  infecting 
  a 
  sufficiently 
  susceptible 
  person; 
  and 
  it 
  is 
  possible 
  that 
  such 
  infections, 
  and 
  infections 
  

   of 
  a 
  cyclical 
  nature, 
  often 
  take 
  place 
  with 
  game 
  present 
  ; 
  but 
  the 
  persistent 
  biting 
  by 
  many 
  flies 
  that 
  

   results 
  from 
  hunger 
  in 
  the 
  absence 
  of 
  game 
  would 
  render 
  infection 
  more 
  likely 
  even 
  for 
  the 
  

   probably 
  somewhat 
  resistant 
  native 
  by 
  greatly 
  increasing 
  the 
  number 
  of 
  trypanosomes 
  injected. 
  

  

  (8053) 
  2 
  a 
  

  

  