Seroepidemiological study of herpes simplex virus types 1 and 2 in Brazil, Estonia, India, Morocco, and Sri Lanka

Infections with herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) are among the commonest human viral infections. HSV-1 is the usual cause of oro-labial herpes and HSV-2 of genital herpes. Globally, HSV-1 is most commonly transmitted horizontally in childhood, although improvements in socioeconomic conditions in some western countries have resulted in declining rates of childhood infection. ¹ HSV-1 is increasingly recognised as a cause of first episode genital herpes in these countries. ^{2, 3}

HSV-2 is one of the commonest causes of genital ulceration worldwide. HSV-2 is almost always sexually transmitted and as such has been shown to be a good marker of sexual behaviour in populations. ^{1, 4, 5} Up to 70% of genital HSV infections are unrecognised, ⁶ so seroepidemiological studies are critical to understanding the pattern and distribution of infection within populations. Even though the majority of HSV infections are unrecognised, most people who are infected shed virus at some time and are therefore potentially infectious.

There is increasing evidence that HSV-2 facilitates HIV transmission, ^{7, 8} making the development of HSV control methods a priority. ^{6, 9} Recent efforts to develop an HSV-2 vaccine have met with limited success, ^{10, 11} but these trials have underscored the importance of collecting population based HSV type specific data. In particular, two phase III trials of a prospective subunit vaccine for HSV-2 were found to prevent disease in women who were HSV-1 naive. ¹⁰ If these results are confirmed, age specific data on HSV-1 seroprevalence will be critical to defining country specific vaccine strategies.

Recently, serological tests that can accurately distinguish between antibodies to HSV-1 and HSV-2 have become commercially available allowing more widespread study of the epidemiology of these infections. In this paper we present the results of a study designed to estimate the age and sex specific seroprevalence of HSV-1 and HSV-2 infections in selected populations in Brazil, Estonia, India, Morocco, and Sri Lanka, countries in which there is currently little information about the epidemiology of HSV and with low HIV rates in the general population. ¹²

METHODS

Study populations

Sites were selected on the basis that there were few existing data on HSV seroepidemiology and they had the appropriate infrastructure to conduct this research. Each centre collected samples...