V. Evaluation of Cross-Immunity against Type 1 Dengue Fever in Human Subjects Convalescent from Subclinical Natural Japanese Encephalitis Virus Infection and Vaccinated with 17D Strain Yellow Fever Vaccine
Information has been presented to show that amebiasis surveys conducted in different geographical locations in the Western Hemisphere are too few and too fragmentary to provide a complete demographic picture of the infection. For many areas no surveys have been undertaken; for many others the data are based on unrepresentative groups of the population or too few persons have been examined to provide significant statistics. Moreover, most surveys have employed a single technic on a single stool specimen; hence the positive cases reported constitute only a fraction of the true incidence in the particular area.
In spite of the discrepancies pointed out, there is substantial evidence that amebiasis exists in an appreciable portion of the population of the Western Hemisphere, from Central West Canada (52° 30′ N. latitude) to the Strait of Magellan (52° S. latitude); that it is much more intensely endemic in the American tropics than in the temperate zones; and that in areas like the United States the incidence figure may possibly average as high as 20 per cent, or double that of previously accepted estimates.