Why are men more likely to be diagnosed with TB?

4 Jan 2010

Paul Chinnock

Source: PLoS Medicine (see original article or PDF)

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Citation: Neyrolles O, Quintana-Murci L (2009). Sexual Inequality in Tuberculosis. PLoS Med 6(12): e1000199.

2009 Neyrolles, Quintana-Murci

Why should it be that cases of tuberculosis are so much more common in men than in women? Worldwide, notified cases of TB of the lungs in adult males are about twice as numerous as those in adult females. While it is recognized that, due to socioeconomic factors, women often have more limited access to health care and thus many with TB go undiagnosed, it does seem that men are more vulnerable to this infection. The issue is discussed in detail in a PLoS Medicine “Research in Translation” article, based in particular on what has been learned from six key studies in this area.

In the view of the authors, Olivier Neyrolles and Lluis Quintana-Murci, “Large prevalence surveys have suggested that the sex bias observed in pulmonary TB cases may result partly from genuine biological differences in male and female susceptibility to M. tuberculosis infection or the development of TB disease”. The evidence available suggests that 5–10% of people exposed to M. tuberculosis develop TB, and up to 70% of those who do develop the disease are male. As Neyrolles and Quintana-Murci point out, “...the human population as a whole is remarkably resistant to M. tuberculosis, but women seem to be even more resistant to the bacillus than men”.

There is an absence of information on the role of biological gender in TB. The authors identify sexual hormones, sex-related genetic background and genetic regulations, and metabolism as factors that could explain the susceptibility differences between men and women. They call for more research in these and other aspects of TB. The findings of such research would be useful in the planning and implementation of interventions at community level.