Using condoms consistently can reduce the risk of both men and women acquiring herpes simplex virus type 2 (HSV-2), the most common cause of genital herpes, according to data from researchers from United States, published in the November 15th edition of the Annals of Internal Medicine. An accompanying editorial argues that these data provide another nail in the coffin for arguments against promoting condom use as part of a comprehensive risk reduction strategy for sexually transmitted infections (STIs) and HIV.
Herpes simplex virus type 2 (HSV-2), is a sexually transmitted infection that is chronic, widespread, and infectious during both its symptomatic and asymptomatic periods. This infection is a significant factor for increased risk of acquisition and transmission of HIV. A 2002 meta-analysis of studies on HSV-2 found that infection with HSV-2 doubled the risk of becoming infected with HIV through sexual transmission. In addition, HSV-2 is the leading cause of genital ulcer disease worldwide. Although condom use has been recommended as a way of reducing the risk, this has been based on limited data regarding effectiveness, although a 2001 study by the same study group found that condoms can protect women from HSV-2 infection.
A total of 1843 individuals (1365 men and 478 women) at high risk of herpes infection were followed for 18 months in this prospective cohort study that analysed data from a failed HSV-2 preventative vaccine trial. All participants were considered at high risk of herpes due to having had either four of more sexual partners, or another STI during the year prior to enrolment, or both. The median age of participants was 27; 62% were white, 32% African-American, and 6% Asian, Hispanic or other ethnicities; and 64% were infected with HSV-1 (associated with oral herpes, but which can be transmitted to the genitals via oral-genital contact) at baseline.
During the study period, 118 (6.4%) of participants acquired HSV-2, and the rate of acquisition did not differ significantly between men (5.1 per 100 person-years; 95% CI, 4.1-6.3) and women (5.7 per 100 person-years; 95% CI, 4.1-8.1). However, the incidence rate did differ significantly by ethnicity (p
In multivariate analyses, gender, sexuality, ethnicity and age were significantly associated with HSV-2 acquisition. Compared with heterosexual men, heterosexual women (Hazard Ratio, 1.79; CI, 1.13-2.83) and men who have sex with men (HR, 2.65; CI, 1.34-5.25) were at increased risk of acquiring HSV-2. African-Americans were almost four-times more likely (HR, 3.77; CI, 2.45-5.80) to acquire HSV-2 than white participants. In addition, participants aged less than 27 were more likely to acquire HSV-2 than those aged over 27 (HR, 1.62; CI, 1.06-2.47).
The participants were divided into three groups according to the self-reported frequency of condom use during vaginal or anal intercourse: 0-25%, 25-75% and >75% of the time. Overall, 688 (40%) reported using condoms 0-25% of the time, of whom 47 acquired HSV-2. Another 535 reported using condoms 25-75% of the time, of whom 26 acquired HSV-2. A further 496 reported using condoms more than 75% of the time, of whom 23 acquired HSV-2. This included 210 who said they used always used condoms, of whom 12 acquired HSV-2.
The researchers found that for each of the groups (0-25%, 25-75% and >75% of the time) increasing use of condoms was associated with a 26% reduced risk of HSV-2 acquisition. "Although some participants became infected with HSV-2 despite using condoms, the risk for transmission was substantially reduced with more frequent condom use," they write. "The inability of condoms to protect absolutely, even when used for every sexual act, is demonstrated by the occurrence of infection among those participants who reported using condoms 100% of the time. However, we did not have information on whether the condoms were used correctly." They add that, "social desirability bias, defined as over-reporting of condom use because that it what is perceived to be desired by the interviewer, also contributes to reduced estimates of the effectiveness of condoms."
Although 19 (2.9%) of the 659 participants at risk for HSV-1 infection became infected with HSV-1, no statistically significant association between condom use and HSV-1 infection was found. This is probably because condoms are less frequently used for oral-genital sex.
An accompanying editorial by Dr Edward Hook of the University of Alabama, points out that although chemophrophylaxis with long-term administration of valaciclovir reduces HSV-2 transmission, in the US, for example, only 10% of those infected with HSV-2 are aware of their infection, and this is likely to be even higher in Africa, where HSV-2 is endemic.
Although five years ago, when the current abstinence-focused US HIV and STI prevention policy was being formulated, there was insufficient evidence regarding the protective effect of condoms on genital herpes transmission. This, he argues, is no longer the case.
He concludes that for now, "condoms remain the best proven currently available means to reduce the risk for [HIV and STIs] in at-risk persons. Unfortunately, these individuals do not use condoms as much as they should. Clinicians should tell their at-risk patients that condoms can substantially reduce their risk for these diseases if they use them regularly. This simple message is our best weapon against [HIV and STIs]."
Wald A et al. The relationship between condom use and herpes simplex virus acquisition. Ann Intern Med 143 (10): 707-713, 2005.
Hook E. An ounce of prevention. Ann Intern Med 143 (10): 751-752, 2005.