More on the Relation between AIDS Cases and HIV Prevalence

To the Editor: There is considerable uncertainty in estimates of the current and future prevalence of the human immunodeficiency virus (HIV). Salzberg and Dolins (April 6 issue)¹ state that the ratio of the number of HIV carriers at the beginning of a given year to the number of cases of the acquired immunodeficiency syndrome (AIDS) diagnosed during the year (ratio R) is approximately 25. They propose to use this ratio to estimate both the current and the future prevalence of HIV in given populations. However, this ratio does not remain constant throughout an epidemic and may vary among transmission groups…