﻿ENTOMOLOGICAL 
  ASPECTS 
  OF 
  AN 
  OUTBREAK 
  OF 
  SLEEPING 
  SICKNESS. 
  349 
  

  

  existing 
  on 
  the 
  Simiyu 
  ; 
  while 
  G. 
  swynnertoni, 
  now 
  very 
  much 
  a 
  " 
  man 
  " 
  fly, 
  and 
  

   strains, 
  at 
  least, 
  of 
  palpalis, 
  might, 
  theoretical^, 
  produce 
  the 
  disease 
  merely 
  where 
  

   man 
  is 
  so 
  very 
  much 
  more 
  available 
  than 
  the 
  game 
  that 
  it 
  becomes 
  easier 
  to 
  prey 
  

   on 
  him. 
  

  

  Corroborative 
  Observations 
  from 
  other 
  Sources. 
  

  

  Taute 
  and 
  Huber 
  specially 
  state 
  of 
  the 
  roadside 
  foci 
  of 
  human 
  trypanosomiasis 
  

   behind 
  Kilwa 
  and 
  Lindi 
  and 
  further 
  south 
  the 
  most 
  interesting 
  fact 
  that 
  they 
  were 
  

   confined 
  to 
  water-holes 
  and 
  river-banks 
  that 
  were 
  the 
  halting-places 
  for 
  Yao 
  labourers 
  

   passing 
  from 
  the 
  southern 
  infected 
  foci 
  to 
  the 
  Lindi-Kilwa 
  plantations, 
  and 
  that 
  

   cases 
  did 
  not 
  occur 
  in 
  the 
  surrounding 
  country 
  ; 
  and 
  they 
  remark 
  that 
  one 
  of 
  them, 
  

   the 
  Kilwa 
  (Kilimila) 
  water-hole, 
  was 
  not 
  on 
  the 
  main 
  road 
  used 
  by 
  the 
  local 
  population 
  

   but 
  on 
  a 
  deviation 
  particularly 
  used 
  by 
  these 
  labourers 
  from 
  the 
  infected 
  area. 
  

   G. 
  morsitans 
  is 
  stated 
  to 
  have 
  been 
  abundant 
  at 
  and 
  around 
  the 
  water-hole, 
  and 
  it 
  

   is 
  likely 
  that 
  we 
  have 
  in 
  each 
  of 
  these 
  instances 
  a 
  case 
  of 
  the 
  introduction 
  of 
  man- 
  

   borne 
  infection 
  into 
  the 
  main 
  human 
  meeting-places 
  on 
  roads 
  on 
  which 
  the 
  fly 
  was 
  

   concentrating 
  much 
  on 
  man. 
  Taute 
  mentions 
  also 
  (Minutes 
  of 
  Evidence 
  taken 
  by 
  

   the 
  Interdepartmental 
  Committee 
  on 
  Sleeping 
  Sickness, 
  1913-14, 
  p. 
  231) 
  that 
  

   the 
  sleeping 
  sickness 
  districts 
  of 
  German 
  East 
  Africa 
  were 
  in 
  general 
  ones 
  that 
  

   were 
  not 
  very 
  rich 
  in 
  game, 
  and 
  (in 
  another 
  place) 
  he 
  quite 
  correctly 
  lays 
  stress 
  

   on 
  the 
  fact 
  that 
  morsitans 
  is 
  not 
  merely 
  a 
  game 
  fly, 
  but 
  a 
  man 
  fly 
  also, 
  and 
  that 
  

   it 
  will 
  make 
  man 
  its 
  chief 
  blood 
  supplier 
  after 
  the 
  shooting-off 
  of 
  all 
  antelopes. 
  

   Shircore, 
  in 
  one 
  of 
  his 
  very 
  excellent 
  contributions 
  to 
  the 
  subject 
  of 
  the 
  tsetse 
  problem, 
  

   has 
  referred 
  to 
  the 
  concentrations 
  of 
  the 
  fly 
  that 
  in 
  Nyasaland 
  collect 
  round 
  villages 
  

   in 
  forest 
  and 
  on 
  the 
  paths 
  between 
  villages, 
  " 
  so 
  that 
  the 
  villagers 
  are 
  constantly 
  

   fed 
  on 
  for 
  the 
  greater 
  part 
  of 
  the 
  year 
  by 
  these 
  flies, 
  both 
  in 
  and 
  every 
  time 
  they 
  leave 
  

   or 
  return 
  to 
  their 
  villages 
  " 
  (Minutes 
  of 
  Evidence, 
  p. 
  274). 
  I 
  understand 
  that 
  he 
  

   refers 
  to 
  the 
  sleeping 
  sickness 
  area. 
  

  

  May 
  {op. 
  cit., 
  p. 
  214) 
  states, 
  " 
  The 
  majority 
  of 
  cases 
  have 
  been 
  found 
  in 
  the 
  vicinity 
  

   of 
  main 
  traffic 
  routes 
  (game 
  is 
  generally 
  less 
  abundant 
  in 
  the 
  vicinity 
  of 
  these 
  routes 
  

   than 
  in 
  many 
  other 
  localities 
  . 
  . 
  where 
  the 
  disease 
  is 
  absent 
  or 
  rarely 
  found), 
  

  

  this 
  lending 
  some 
  support 
  to 
  the 
  view 
  that 
  it 
  is 
  transmitted 
  from 
  man 
  to 
  man 
  rather 
  

   than 
  that 
  game 
  is 
  the 
  chief 
  reservoir. 
  This 
  occurrence 
  of 
  the 
  disease 
  along 
  the 
  main 
  

   traffic 
  routes 
  is 
  so 
  marked," 
  etc. 
  Still 
  speaking 
  of 
  Northern 
  Rhodesia, 
  he 
  goes 
  on 
  

   to 
  suggest 
  that 
  " 
  taking 
  into 
  consideration 
  the 
  scattered 
  nature 
  of 
  the 
  population, 
  

   the 
  disease 
  might 
  remain 
  for 
  years, 
  if 
  not 
  indefinitely, 
  endemic 
  ; 
  slight 
  local 
  exacer- 
  

   bations 
  from 
  time 
  to 
  time 
  being 
  accounted 
  for 
  by 
  some 
  such 
  circumstances 
  as 
  increased 
  

   opportunity 
  of 
  infection 
  for 
  the 
  fly 
  " 
  [e.g., 
  by 
  concentration 
  due 
  to 
  game 
  removal. 
  — 
  

   C. 
  F. 
  M. 
  S.]. 
  He 
  attributes 
  the 
  larger 
  number 
  of 
  cases 
  in 
  Nyasaland 
  " 
  to 
  the 
  much 
  

   greater 
  density 
  of 
  the 
  native 
  population 
  along 
  the 
  shores 
  of 
  Lake 
  Nyasa 
  and 
  conse- 
  

   quent 
  increased 
  opportunity 
  for 
  infection 
  and 
  transmission." 
  That 
  even 
  famine, 
  

   by 
  itself 
  ,will 
  not 
  necessarily 
  lead 
  to 
  the 
  development 
  into 
  epidemic 
  or 
  sporadic 
  human 
  

   trypanosomiasis 
  of 
  the 
  Nyasaland 
  type 
  is 
  shown 
  by 
  Kinghorn's 
  statement 
  {op. 
  cit., 
  

   p. 
  259) 
  as 
  to 
  the 
  trying 
  years 
  1911-13 
  in 
  Northern 
  Rhodesia. 
  This 
  might 
  suggest 
  

   that 
  the 
  disease 
  was 
  endemic 
  in 
  the 
  latter 
  country, 
  but 
  that 
  Usukuma 
  was 
  virgin 
  

   ground, 
  or, 
  more 
  likely, 
  that 
  the 
  famine 
  in 
  Rhodesia 
  did 
  not 
  coincide 
  to 
  the 
  same 
  

   extent 
  as 
  on 
  the 
  Simiyu 
  with 
  a 
  marked 
  diminution 
  of 
  the 
  game 
  and 
  a 
  widespread 
  

   and 
  lasting 
  concentration 
  of 
  tsetses 
  on 
  man. 
  Both 
  May 
  and 
  Kinghorn 
  draw 
  attention 
  

   to 
  the 
  retrogression 
  of 
  the 
  disease 
  in 
  Rhodesia 
  " 
  although 
  all 
  the 
  conditions 
  favour- 
  

   able 
  to 
  its 
  spread, 
  viz., 
  an 
  abundant 
  reservoir 
  " 
  [the 
  game 
  — 
  the 
  italics 
  are 
  mine], 
  

   " 
  an 
  ubiquitous 
  and 
  plentiful 
  vector 
  and 
  lowered 
  vitality 
  among 
  the 
  natives, 
  have 
  

   been 
  present" 
  (Kinghorn). 
  May 
  in 
  his 
  evidence 
  before 
  the 
  Committee 
  (p. 
  211) 
  

   gives 
  an 
  instance 
  of 
  a 
  traction-engine 
  road 
  (from 
  the 
  Kansanshi 
  Mine 
  into 
  Belgian 
  

   territory) 
  on 
  which 
  practically 
  no 
  game 
  had 
  been 
  seen 
  for 
  two 
  years, 
  yet 
  tsetses 
  

  

  