Objective: To determine the prevalence of antibody to herpes simplex virus type 2 (HSV-2) in patients attending a general public antenatal clinic and three public sexually transmitted disease (STD) clinics in Sydney.
Background: Highly specific tests for herpes simplex type 2 antibody, using the glycoprotein G2, have been recently introduced, allowing determination of past asymptomatic infection. Overseas studies have confirmed the long held suspicion that asymptomatic infection is more common than clinical genital herpes. The seroprevalence of HSV-2 in antenatal and STD clinic patients varies markedly in different countries. These are the first data available for Australia by means of this highly specific test.
Design: Cross-sectional study of seroprevalence in these two patient groups. Sera used in the antenatal study were those submitted for routine antenatal screening for viral markers.
Participants: Two hundred and twenty-nine consecutive patients attending the Westmead Hospital antenatal clinics, and 107 consecutive patients attending three public STD clinics.
Hypotheses: That Australian populations show a relatively high prevalence of past asymptomatic infection with HSV-2; and that higher rates of infection will be found in patients attending STD clinics and with past or current histories of STDs.
Main outcome measures: Comparison of HSV-2 seroprevalence between antenatal clinic patients and STD clinic patients; and associations of HSV-2 antibody with age, sex, occupation, country of birth, a history of current or past STDs and antibody to HSV-1.
Results: Antibody to HSV-2 was found in 14.5% of antenatal clinic patients and 40% of STD clinic patients. None of the antenatal patients and less than half of the seropositive STD clinic patients reported clinical genital herpes. Associations with age, socioeconomic status and previous HSV-1 infection were less marked than in studies from the United States. Female STD clinic patients had a significantly higher seroprevalence than males and three times the seroprevalence of age-matched antenatal clinic patients. The correlation between HSV-2 antibody and current gonorrhoea was more marked than that between HSV-2 and other STDs.
Conclusion: Asymptomatic infection with HSV-2 is quite common in Australian antenatal patients and more common in patients with STDs, who have higher rates of sexual exposure.