﻿THE 
  YELLOW 
  FEVER 
  SITUATION 
  IN 
  THE 
  AMERICAS 
  1 
  

  

  By 
  Wilbur 
  A. 
  Sawyeb 
  

   Director, 
  International 
  Health 
  Division, 
  The 
  Rockefeller 
  Foundation 
  

  

  The 
  early 
  history 
  of 
  yellow 
  fever, 
  dominated 
  by 
  records 
  of 
  epi- 
  

   demics 
  in 
  cities 
  and 
  outbreaks 
  on 
  ships, 
  was 
  largely 
  characterized 
  by 
  

   waves 
  of 
  the 
  disease. 
  There 
  were 
  outstanding 
  epidemic 
  years 
  in 
  which 
  

   the 
  disease 
  extended 
  to 
  the 
  seaport 
  cities 
  of 
  Spain, 
  to 
  Philadelphia, 
  

   and 
  to 
  New 
  York, 
  or 
  up 
  the 
  Mississippi 
  to 
  Memphis 
  and 
  beyond, 
  and 
  

   also 
  years 
  in 
  which 
  there 
  was 
  widespread 
  involvement 
  of 
  Central 
  

   America 
  and 
  Mexico. 
  The 
  same 
  changeable 
  epidemic 
  picture 
  has 
  been 
  

   observed 
  in 
  West 
  Africa 
  and 
  South 
  America. 
  The 
  disease 
  was 
  never- 
  

   theless 
  continuously 
  present 
  for 
  long 
  periods 
  in 
  certain 
  cities, 
  like 
  

   Habana 
  and 
  Guayaquil, 
  where 
  the 
  supply 
  of 
  susceptible 
  persons 
  and 
  

   an 
  abundance 
  of 
  aegypti 
  mosquitoes 
  (Aedes 
  aegypti) 
  permitted 
  the 
  

   disease 
  to 
  appear 
  year 
  after 
  year. 
  The 
  outstanding 
  characteristics 
  

   of 
  the 
  historic 
  yellow 
  fever 
  picture 
  were 
  sudden 
  epidemic 
  extensions 
  

   of 
  the 
  disease 
  far 
  beyond 
  any 
  known 
  endemic 
  foci, 
  followed 
  by 
  absence 
  

   of 
  the 
  disease 
  or 
  relative 
  quiescence. 
  

  

  THE 
  SHIFTING 
  LOCALIZATION 
  OF 
  JUNGLE 
  TELLOW 
  FEVER 
  

  

  Observations 
  during 
  the 
  past 
  few 
  years 
  in 
  several 
  countries 
  of 
  South 
  

   America 
  suggest 
  that 
  jungle 
  yellow 
  fever 
  resembles, 
  more 
  closely 
  

   than 
  was 
  at 
  first 
  apparent, 
  the 
  old-time 
  urban 
  aegyp 
  ^'-transmitted 
  

   disease 
  in 
  its 
  tendency 
  toward 
  wavelike 
  epidemics 
  and 
  shifting 
  local- 
  

   ization. 
  The 
  world-wide 
  yellow 
  fever 
  immunity 
  survey, 
  carried 
  out 
  

   from 
  1931 
  to 
  1937, 
  by 
  testing 
  human 
  sera 
  from 
  many 
  countries 
  by 
  

   means 
  of 
  the 
  mouse-protection 
  test, 
  showed 
  that 
  immunizing 
  infec- 
  

   tions 
  had 
  recently 
  occurred 
  in 
  many 
  places 
  previously 
  supposed 
  to 
  be 
  

   free 
  of 
  infection 
  (Sawyer, 
  Bauer, 
  and 
  Whitman, 
  1937; 
  Soper, 
  1937a) 
  

   and 
  the 
  systematic 
  collection 
  and 
  histologic 
  examination 
  of 
  liver 
  speci- 
  

   mens 
  in 
  South 
  America 
  showed 
  that 
  fatal 
  cases 
  of 
  yellow 
  fever 
  were 
  

   occurring 
  in 
  scattered 
  locations 
  in 
  the 
  newly 
  revealed 
  endemic 
  areas 
  

  

  1 
  The 
  observations 
  on 
  which 
  this 
  paper 
  is 
  based 
  have 
  been 
  made 
  in 
  large 
  part 
  by 
  members 
  

   of 
  the 
  staff 
  of 
  the 
  International 
  Health 
  Division 
  of 
  The 
  Rockefeller 
  Foundation 
  and 
  of 
  the 
  

   health 
  authorities 
  of 
  the 
  governments 
  with 
  which 
  the 
  Division 
  Is 
  collaborating. 
  The 
  paper 
  

   is 
  here 
  reprinted 
  by 
  permission 
  from 
  the 
  Proceedings 
  of 
  the 
  Eighth 
  American 
  Scientific 
  

   Congress, 
  vol. 
  6, 
  1942. 
  

  

  575 
  

  

  