(10 May 2002)

Researchers who have been following a group of young people in New Zealand (NZ) for more than 20 years have found that the number of people who acquire genital herpes peaks in this study group later than in populations in other parts of the world.[1]

The proportion of the study group with a genital herpes infection increased from the equivalent of 8.1 cases per 1000 at age 21, to 13.5 cases per 1000 at age 26 – after taking into account the number of years that people had been sexually active.

The leader of the study, Dr Jason Eberhart-Phillips, says the increase in HSV-2 (the virus that causes the majority of genital herpes infections) is not because people have more partners between the ages of 21 and 26 – in fact, the rate at which individuals changed partners was less by the time they were 26 than when they were 21.

Co-author Professor Tony Cunningham, a herpes expert from Australia, says: ‘What this study shows is that HSV-2 peaks in this group at a later age – between 21 and 26 – than in many other countries. This is good news.’

Professor Cunningham adds: ‘This is not a rising incidence of HSV-2 in NZ. To demonstrate that we would have to test the same age group, or the equivalent sample of population, several years apart.’

Genital herpes is far less common in New Zealand than in the USA, where nearly 22% of people over the age of 12 have HSV-2.[2]

Global figures are hard to come by, but in Canada, studies on pregnant women found 17.3% had HSV-2,[3] compared with around 10% in pregnant women in Spain, Italy and the UK.

1. Eberhart-Phillips J, Dickson N, Paul C, et al: Rising incidence and prevalence of herpes simplex type-2 infection in a cohort of 26-year-old New Zealanders. Sex Transm Infect 2001;77:353–357

2. Fleming DT, McQuillan GM, Johnson RE, et al: Herpes simplex virus type 2 in the United States, 1976 to 1994. New Engl J Med 1997; 337:1105–1111

3. Patrick DM, Dawar M, Cook DA et al: Antenatal seroprevalence of HSV-2 in Canadian women: HSV-2 prevalence increases thoughout the reproductive years. Sex Transm Dis 2001;28:424–428