Sousa & Vandamme demonstrate a robust correlation between HIV-2 prevalence at the time of the 1980s surveys and the absence of indigenous practices of male circumcision earlier in the century.  This is a complex and interdisciplinary study, involving some of the earliest large-scale, West African serological surveys of HIV-2 (1980s) and extensive ethnography of the region throughout the twentieth century.

HIV-2 seems to have crossed the species barrier into humans from a primate called the ‘sooty mangabey’.  The two epicentres of the 1980s HIV-2 epidemic – south-west Côte I’Ivoire and Guinea Bissau – correspond to the two points along the band of sooty mangabey territory where ethnic groups were to be found who did not practice circumcision (Côte I’Ivoire), or performed it only late in life or very intermittently (Guinea Bissau).  The complexity of this study arises from the fact that, thanks to waves of islamicization, male circumcision has been widely adopted across the region even in areas where it was traditionally prohibited.  Hence investigation of the correlation with HIV-2 emergence, probably in the 1940s, required the authors to go back to ethnographic accounts preceding islamicization.

Of course, the certainty of a causal link cannot be established.  But Sousa & Vandamme discover a strong negative correlation between male circumcision and HIV-2 (Spearman rho = -0.546).  Their results are supported by studies that establish the same negative relationship with HIV-1, both in sub-Saharan Africa (Moses and Plummer) and, more recently in Papua New Guinea (MacLaren & Vallely/STIs).  A likely causative mechanism might be the prevalence of ulcerative sexually transmitted infections (Weiss & Hayes/STIs).

So Sousa & Vandamme offer an additional ‘ecological’ reinforcement of the public health rationale for encouraging voluntary male medical circumcision (VMMC).  Yet what is also interesting, from a public health perspective, is the importance their study attributes to culture in the adoption of a practice like male circumcision.  In the present case, for once, the impact would appear to have been very positive from the medical point of view. The authors speak, for example, of islamicization, along with ethnic intermarriage in the cities, as having given rise to ‘social pressure to be circumcised in order to be accepted by women’, and the ‘abandonment of traditional prohibitions of male circumcision’. Of course, the impact of indigenous culture may often be less benign from a medical point of view – as the source of conservative attitudes that tend to hold back and limit the uptake of VMMC.  As, for example, where males have seen male circumcision as the practice of potentially hostile neighbouring groups (Cultural constraints on uptake of circumcision/STI/blogs), or as a practice uniquely suited to those younger age groups on whom it was traditionally performed (Mbabazi/STIs).  But, either way, it is noteworthy that the influence of local culture would often seem to be so decisive.  So there may be an argument, for electing to promote infant circumcision, as an evidently medical practice that runs less risk of falling foul of prevailing cultural attitudes that restrict ‘demand’ (Gray & Kigozi/STIs; Feasibility of infant circumcision/STIs/blogs).

.