The focus on chlamydia in this issue of STI is timely. A debate on the second day of the 17th International Society for STD Research and 10th International Union against STI meeting in Seattle on 30 July will address the topic “Epidemiology of chlamydial infection: are we losing ground?” The first “special issue” about sexually transmitted Chlamydia trachomatis in this journal, then called the British Journal of Venereal Diseases, was published in December 1972 when seven articles examined diagnostic and clinical aspects of a new sexually transmitted infection.¹ Chlamydia is now the most commonly reported of all infections in countries like the USA and Sweden. The papers collected here address new aspects of C trachomatis but also articulate the growing uncertainties about our efforts to control this pathogen.

Screening asymptomatic individuals seems to many people to be the obvious solution to prevent the transmission and adverse consequences of chlamydia,² including preterm delivery and premature rupture of membranes in pregnant women. (see p 314)³ It is also a very expensive solution. (see p 267)⁴ The economic modelling and evaluation study by Adams et al shows that it is going to be difficult for the opportunistic strategy being implemented by the National Chlamydia Screening Programme in England to be cost effective. Proactive screening, using population registers to identify and invite people to be screened regularly, is usually assumed to be more expensive to run than opportunistic screening. Robinson et al⁵ estimated the health service and patient costs of a postal chlamydia screening approach in England. (see p 276) The cost per invitation was actually similar to that of an organised opportunistic screening programme.⁶

We are learning the hard way that delivering chlamydia screening effectively and efficiently is easier than it sounds.⁷ If …