Histoplasmin testing results are reported for groups of schoolchildren and village populations, totalling more than 10,000 persons, in ten different countries of Africa and Asia. All tests were given by intradermal injection of 0.1 ml. of histoplasmin dilution, the reactions were read in 48–72 hours by measuring and recording the transverse diameter of induration in millimeters, and no reactions were classified as “positive” or “negative” by the field teams. Few reactions exceeded 8 mm. in diameter for the groups tested in Libya, Egypt, Iran, Pakistan, India, Taiwan, and Burma, suggesting that histoplasmin sensitivity is probably absent in these areas. In Viet Nam and Indonesia, where a small proportion (less than 10 per cent) of the reactions tend to be concentrated around 16 mm. in diameter, specific histoplasma infection may exist although the possibility of cross-reactions with a sensitizing agent other than histoplasma must be considered. In the Sudan, where the entire country was sampled for histoplasmin sensitivity, very few reactions could be regarded as evidence of specific infection except in the southern province of Equatoria, where about 15 per cent of the reactions measured more than 10 mm. in diameter. The distributions were clearly separated into two groups interpreted as representing the infected and uninfected segments of the populations tested. Histoplasmosis, though low in prevalence, apparently exists in the central-eastern part of the African continent.
Present address: Tuberculosis Program, U. S. Public Health Service, Washington 25, D. C.
Present address: Royal Netherlands Tuberculosis Association, Riouwstraat 7, The Hague, Holland.