The third National Survey of Sexual Attitudes and Lifestyles (Natsal) was long awaited and finally hit the British press just before World AIDS Day 2013. You can access a fascinating range of data in six open access Lancet papers, accessible through www.natsal.ac.uk. The sexual health research and clinical communities are however only too well aware of the complex pitfalls we face in this particularly sensitive field of behavioural research. So we are delighted to publish perhaps the most important papers by the Natsal team-an account of their methods Phelps et al1 a exploration of how bias in Natsal has changed over the three decennial surveys Prah et al2 and a fascinating editorial by Mercer, Wellings and Johnson3 describing its development and origins in earlier surveys. Many clinicians, as well as researchers, use questionnaires and surveys in their working lives. This suite of papers, along with the growing archive of past and present Natsal questions, provides an immense resource for those who need to find valid ways of measuring the sexual behaviour of populations. Gone are the days when everyone designed his or her own survey – good research, on any scale, needs to build on the methods that have been painstakingingly developed by groups like the Natsal team.

Vaginal microbiology emerges as an important theme this month. The transmissibility of candidal infection among women who have sex with women is a clinical question many of us need to address. Muzny and colleaugues4 present a mixed methods study exploring predictors of candida and of concordance within couples with some surprising results. Another paper by Guédou5 assesses the assocations of intermediate vaginal flora (IVF) and of bacterial vaginosis (BV). The authors suggest that we might learn more by comparing normal vaginal flora with both BV and IVF, than by focussing predominantly on BV.

As ever, HIV testing is a popular topic. Guidelines do not automatically result in a change of practice, and this month Elmahdi and colleagues present a systematic review of the implementation of HIV testing guidelines in the UK.6 Disappointingly they conclude that adherence to guidelines is poor outside the sexual health and antenatal clinics, and that this is related to low levels of provider offer. As yet we lack effective surveillance of testing, and this is urgently needed if we are to reduce rates of late diagnosis. A rather different approach to HIV testing is proposed in a Spanish paper, where Fernández-Balbuena and colleagues7 report the results of a street testing initative aimed at reaching individuals who had never tested.

“Point of care” tests remain a topic of interest, though I find it hard to resist the temptation to point out that Gram stains, dark ground microscopy and wet mounts for Trichomonas vaginalis are point of care tests (POCT) It is indisputable that the new generation of POCT have a different role, and our readers will find Turner et al's exploration of POCT for gonorrhoea and chlamydia instructive.8 An editorial9 by Alec Miners reflects on these interesting questions.

This issue also presents important papers on behavioural risk in men who have sex with men (MSM),10 11 the epidemiology and prevention of STI and HIV in Africa.12 13 14 15 Do please share your thoughts at @sti_bmj,via the website or consider proposing a blog to our blogmaster via leslieginlewes@yahoo.co.uk