A review of sex differences in the epidemiology of tuberculosis

Globally, the prevalence of infection with Mycobacterium tuberculosis is similar in males and females until adolescence, after which it is higher in males. In industrialized countries in the middle of this century (1930s to 1950s), females aged 15 to 34 years had higher tuberculosis notification rates than males of the same age. However, as notification rates in these countries decreased over time, rates in males became higher than those of females for all ages over 15. Present notification rates of both sexes combined in many developing countries are similar to those of industrialized countries in the middle of the century, although the sex and age pattern is similar to that in industrialized countries at present, with men's disease rates exceeding women's after the age of 15. These findings raise the possibility that cases of tuberculosis among women are being under-reported in developing regions. This is supported by the results of a study comparing active and passive case-finding in which women with tuberculosis were under-notified to public health authorities when relying on passive case-finding. In addition, epidemiological evidence from the pre-human immunodeficiency virus (HIV) era shows that young to early-middle-aged women progress from infection to disease with greater frequency than do men. This elevated frequency of progression among women now coincides with a peak in HIV prevalence among women of the same age. National Tuberculosis Programmes must assess possible sex differences that exist in their countries. In addition, information about the risks of tuberculosis in younger women should be incorporated into maternal and child health, and HIV/AIDS programmes. Further research comparing sex differences in tuberculosis rates, preferably using active as well as passive case-finding, would be necessary to determine whether young women are undernotified in developing countries.