Commentary: Developing preventive strategies in Europe

FM Cowan

ZAPP, 103–105 Rotten Row, Harare, Zimbabwe. Present address: Department of Sexually Transmitted Diseases, University College London, Mortimer Market Centre, Crapper Street,London, UK. E-mail:fcowan{at}gum.ucl.ac.uk

With the recent increase in availability of relatively cheap and sensitive type-specific antibody tests for Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), the sero-epidemiology of these infections in different countries around the world is becoming better defined. Studies demonstrate wide variation in HSV seroprevalence according to geographical location, socioeconomic and behavioural factors.1 This study from the University Hospital in Rotterdam, Holland is interesting in that it explores the prevalence of infection among attendees at the same sexually transmitted disease (STD) clinic at two different time points. The authors were able to demonstrate a fall in prevalence of antibodies to both HSV-1 and HSV-2 between 1993 and 1998 of around 40%, after controlling for demographic and behavioural factors. While it is true that this apparent fall in seroprevalence may reflect changes in the clientele attending this STD clinic that have been inadequately controlled for in the statistical analysis, it more likely reflects real changes in the seroprevalence of these infections in this population over this time period.

Although infection with HSV-1 is almost universal in developing countries, more recently prevalence rates as low as 40–50% have been reported among middle-class adults in Western communities. This reduction in prevalence has been attributed to the improvement in living standards in the West over the course of the last century. As in this study from Holland, workers from the Public Health Laboratory Service in the UK have been able to demonstrate that the overall prevalence of antibodies to HSV-1 in the general population has fallen in recent years. In the UK at least, prevalence of antibody to HSV-1 increases with age until about 5 years, then stabilizes until around 15 years old, suggesting that, as has been shown in the Dutch study, sexual transmission is becoming increasingly important as a route of transmission for this virus.2 HSV-1 is now the commonest cause of primary genital herpes presenting to STD clinics in many areas of the UK.

There has been considerable concern, following publication of HSV-2 seroprevalence data collected as part of the Third National Health and Nutrition Survey (NHANES 3) in the US, that the world is in the grip of an HSV-2 epidemic. NHANES 3 was conducted among a representative sample of adult Americans between 1988 and 1992, and showed that the seroprevalence of HSV-2 among adults in the general population had increased from 16.8% in 1978 (when NHANES 2 was conducted) to 21.7% in 1990.3 Data from developing countries also demonstrate high levels of infection among certain sectors of the population.4,5 Widespread population screening of HSV-2 antibody, coupled with education aimed at increasing recognition of genital herpes infection has been advocated to control continued spread of infection. However, prevalence rates of antibody to HSV-2 are much higher in the US than in Europe, where there has been much debate about the likely cost-effectiveness of this approach to improve public health.6 It is therefore interesting that the authors of this Dutch study have demonstrated a fall in the prevalence of HSV-2 antibody among STD clinic attendees between 1993 and 1998, in the absence of HSV-2 antibody screening and specific HSV educational programmes even among STD clinic attendees. It would be nice to think that this reflected a trend towards safer sexual practices among young Dutch people as a result of general education campaigns, although data from other sources are required to substantiate this.

This paper lends further credence to the view that strategies for managing genital herpes at a population level need to be tailored to the local population and that European countries should not be pressured into such strategies on the basis of evidence accrued in the US alone. We need to get more evidence about the seroprevalence of HSV-1 and HSV-2 in both the general, STD and antenatal clinic populations across Europe in order to make informed decisions about likely necessity of introducing screening in these different settings. Formal evaluation of the likely costs and benefits of screening need to be established in different settings to ensure it will indeed benefit the public health.

References

1 Brugha R, Keersmaeker K, Renton A, Meheus A. Genital herpes infection: a review. Int J Epidemiol 1997;26:698–709.[Abstract]

2 Vyse A, Gay N, Slomka M et al. The burden of infection with HSV-1 and HSV-2 in England and Wales: implications for the changing epidemiology of genital herpes. Sex Transm Infect 2000;76:0–4.

3 Fleming DT, McQuillan GM, Johnson RE et al. Herpes simplex virus type 2 in the United States. N Engl J Med 1997;337:1105–11.[Abstract/Free Full Text]

4 McFarland W, Gwanzura L, Bassett MT et al. Prevalence and incidence of Herpes simplex virus type 2 infection among male Zimbabwean factory workers. J Infect Dis 1999;180:1459–65.[ISI][Medline]

5 Weiss HA, Buve A, Robinson NJ, Hayes RJ, van Dyck E and the Study Group on Heterogeneity of HIV Epidemics in African Cities. HSV-2 Seroprevalence and Association with HIV Infection in Four Urban African Populations. Thirteenth Meeting of the International Society for STD Research, July 1999, Denver, CO, USA. Abstract #033.

6 Brugha R, Brown D, Meheus A, Renton A. Should we be screening for asymptomatic HSV-2 infections? Sex Transm Infect 1999;75:142–44.[ISI][Medline]