Sexual inequality in tuberculosis

Abstract

Olivier Neyrolles and Lluis Quintana-Murci review the evidence on why tuberulosis notification is twice as high in men as in women in most countries.

Figure 1. Sex distribution for new smear-positive TB case notification in 2007 in various countries .

Figure 2. Regional (A) and age (B) distribution of the male/female ratio for new smear-positive TB cases in 2007.

(A) Dot-plot in which each dot corresponds to a country. EUR, Europe; SEAR, Southeast Asia; WPR, Western Pacific; AMR, the Americas; AFR, Africa. The bar indicates the mean. (B) Box plot showing the 25th and 75th percentiles, together with the median, with whiskers showing the minimum and maximum male/female ratio for new smear-positive TB cases in 2007 in the Americas. Crosses indicate means. Data were compared with the male/female ratio expected under the hypothesis of neutrality (1, red line) and were analyzed with Mann-Whitney tests (***, p<0.0001) . NS, not significant.

Figure 3. Do sex steroids influence antimycobacterial immunity?

Both innate immune cells (monocytes, macrophages, and dendritic cells) and T cells express specific receptors for steroid hormones, at least a fraction of them . Future experimental work may assess whether sexual hormones, alone or in combination with other immune mediators, influence M. tuberculosis (Mtb) entry (1) and intracellular trafficking and survival (2) in host phagocytes and antigen-presenting cells (APC), the secretion of cytokine and other factors by infected cells (3), antigen presentation (4), and T cell development (5).