Unusual sex differences in tuberculosis notifications across Pakistan and the role of environmental factors

ABSTRACT

In developing countries, only one-third of new tuberculosis cases notified are from women. It is not clear whether tuberculosis incidence is lower in women than men, or whether notification figures reflect under-detection of tuberculosis in women. Pakistan, however, presents an unusual pattern of sex differences in tuberculosis notifications. While 2 of the 4 provinces [Sindh and Punjab] report more notifications from men [female to male ratios 0.81 and 0.89 respectively in 2009], the other 2 provinces [Khyber-Pakhtunkhwa and Balochistan] consistently report higher numbers of smear-positive tuberculosis notifications from women than men [1.37 and 1.40]. No other country is known to have such a large variation in the sex ratios of notifications across regions. Large variations in female to male smear-positive notification ratios in different settings across a single country may indicate that environmental factors, rather than endogenous biological factors, are important in influencing the observed sex differences in tuberculosis notifications.