The Distribution of Yellow Fever Immunity in North America, Central America, the West Indies, Europe, Asia, and Australia, with Special Reference to the Specificity of the Protection Test
Wilbur A. Sawyer,
Johannes H. Bauer AND
Loring Whitman
From the Laboratories of the International Health Division, Rockefeller Foundation, New York
1. Evidence is presented to show that the yellow fever protectiontest in mice, as used in epidemiological surveys, is highlyspecific.
2. Of a total of 876 human sera from Asia and Australia,whereyellow fever has presumably never been present, only 2specimens,or 0.23 per cent, showed protection against yellowfever virus.Among 481 sera from Italy, Spain, Portugal, Canada,and theUnited States, where yellow fever was formerly presentbut isnow absent, only one was protective.
3. A total of1177 sera were tested from the following islandsof the WestIndies: Barbados, Cuba, Jamaica, Puerto Rico, St.Lucia, andTrinidad. Among them were 821 from persons under20 years ofage, none of whom gave blood-serum which was protectiveagainstyellow fever virus. Of 356 sera from adults over 20years old,30, or 8.42 per cent, showed immunity to yellow fever.
4.A total of 1089 sera were tested from Mexico. There was alargepercentage of protective sera from donors of all age-groupsexcept very young children. All sera from children born afterthe year 1925 gave negative results, suggesting that yellowfever has probably disappeared from Mexico within recent years.
5. A total of 1182 specimens were tested from the seven CentralAmerican countries. The results for El Salvador, Guatemala,British Honduras, Honduras, and Nicaragua were similar to thosefor Mexico. The sera from persons under 20 years of age in Panamaand Costa Rica gave no protection against yellow fever virus,while the percentage of immunes in the older persons consideredas one group was about the same as in the other Central Americancountries.