Diphtheria attack rates and cases, and to a much lesser extent case-fatality rates, have fallen steadily within the United States during the past 25 years. However, during 1959 and 1960 there was a halt in this long-term trend. Epidemiologic data on 868 clinical cases of diphtheria occurring in 1959 and 873 cases in 1960 were submitted to the Communicable Disease Center by 45 states. The cases and several major outbreaks tended to concentrate in the southern and southwestern states. Attack rates and deaths were highest for children under 10 years, and attack rates were more than five times greater for nonwhite children.
Analysis of 1960 immunization data shows that 72% of the patients had received no immunizations. Fifty-five per cent of carriers, but only 18% of persons with bacteriologically confirmed cases, had received a primary series. Only 1 person of 58 fatal cases occurring in 1960 had received a primary series. Certain problems for future investigation, disclosed by the surveillance data, are discussed.
Modeling the effects of secular variation of geomagnetic field orientation on the ionospheric long term trend over the past century
