• chlamydia trachomatis
• heterosexual behaviour
• HIV

Last month we published a special issue on the Global Health of men who have Sex with men (MSM). Guest edited by two of our Associate Editors – Stefan Baral and Henry De Vries – it brought together a fascinating range of material on a key population whose needs are regularly explored in this journal.1 There is a great range and diversity of sexual identities and behaviours of MSM across the globe, with cultures creating many ways of assimilating to or dissenting from dominant sexual cultures. Just consider for example the differences between Latin America and India, although MSM are a key population across the globe, and a high priority for prevention and treatment services. The drivers of STI risk in heterosexual populations by contrast are much more variable. Throughout the ages commercial heterosexual sex has been a major driver of STI and HIV in many parts of the world – as you can see in our archived contents from 1925 at http://sti.bmj.com/content/by/year. Yet in developed countries heterosexual commercial sex has generally declined as a driver of transmission, and in the absence of other risks such as drug dependency female commercial sex workers prevalence of many STIs can in some cases be comparable with wider population groups.2 So is not always clear how to target services to heterosexual populations. A hidden population which has been suggested as a focus for intensified testing in the West is swingers, heterosexuals who as a couple have sex with others. Dukers-Muijrers et al present a careful and interesting study of testing and STI patterns among swingers in two Dutch clinics with different approaches to their identification.3 In an accompanying editorial, Cath Mercer puts this research in a wider context and draws lessons for clinical practice from clinic based research and evidence from population surveys.4 With increasing pressure on services in many settings, clinicians will need to consider carefully how they can target both testing services and the precious resource of clinical face to face advice on prevention. Again from the Netherlands, van Aar and colleagues present a space-time cluster analysis which was used to explore evidence for outbreaks that had not yet been recognised.5 In this case the techniques were used to explore increases in syphilis diagnoses among MSM. There are a growing range of outbreak detection methods largely developed in other fields of infectious disease control, which should increasingly be developed for use in the field of STI and HIV transmission. Last year’s special issue on Outbreaks, Guest Edited by Gwenda Hughes and Ian Simms, includes an editorial introducing recent developments in outbreak detection.6

This month a number of papers present important behavioural data on MSM populations. A study of hepatitis C acquisition confirms high rates of drug use and also of fisting and group sex among those newly diagnosed, with a complex interplay between drug use and sexual practices which differs between HIV negative and HIV positive men.7 Clinicians will be fascinated and concerned by Harrison et al’s study of genital Neisseria isolates, which demonstrates anal and urogenital hyperinvasive meningococci and multi-resistant gonococci in hospitalised MSM.8 This relates interestingly to a study by Achterbergh and colleagues on the relationship between anorectal chlamydia and gonorrhoea and the use of douching equipment.9 Regular testing – defined in a Netherlands study as 6 monthly - remains low as shown by Visser et al.10 While PREP offers promise, its takeup is unlikely to reach all groups of MSM at risk of HIV11 and the growing complexity of STI risk must remain an important priority in research and practice.

A few more hot topics cannot go unmentioned: this month we publish registry based estimates of the risk of vertical Chlamydia trachomatis transmission,12 a quantitative study of vaginal flora,13 an interesting assessment of a ‘sample first’ point of care pathway,14 and a sobering study of HIV and hepatitis C prevalence in Iranian street children.15