Measles antibody has been determined by the hemagglutination inhibition test (HAI) of Rosen 1 in 494 serum specimens from members of 12 relatively isolated indigenous populations in New Guinea and Australia. Specimens for this survey were selected from those populations which we considered might be measles-free, or so-called virgin soil areas, or because of well-documented information of their unusual interest because of recent "virgin soil" epidemics of measles. No report of any measles-free area existing today could be found in the literature, so that the current demonstration of measles-free populations of susceptibles is unique. Obviously, such fully susceptible populations are ever at great risk of a "virgin soil" epidemic of measles, and the use of an effective measles vaccine in these communities may be a more urgent matter than in most other populations.
The 12 populations studied include 9 primitive populations of New Guinea, all of which have been without