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Genital herpes caused by herpes simplex virus (HSV) infection is one of the most prevalent sexually transmitted infections (STIs) and the most common cause of genital ulcer disease (GUD) in developed and developing countries. The monitoring of HSV‐2 seroprevalence in pregnant women can identify women at a higher risk of HIV and of neonatal HSV transmission. Very few data are available on type specific seroprevalence of HSV‐2 in China, with only one previous study from southern China. Consequently, we conducted a survey to determine type specific seroprevalence of HSV‐2 and associated risk factors in Fuzhou City, eastern China.
A cross sectional seroprevalence study was conducted from July to September 2002 in an antenatal clinic of Fujian Provincial Maternal and Child Hospital in Fuzhou, China. Of 506 eligible women, 504 (99.6%) agreed to participate. After obtaining informed consent, a questionnaire was administered by a trained female nurse and a genital examination was conducted. Blood samples were collected, centrifuged, and stored at −30°C for serological testing. At the National Center for STD Control, sera were tested for anti‐herpes simplex virus (HSV) type 2 specific IgG antibodies using the HerpeSelect HSV‐2 ELISA (Focus Technologies, CA, USA), per manufacturer's instructions. Assay performance was evaluated in China and reported elsewhere.1 The study was approved by the institutional review committee of the National Center for STD Control, Nanjing.
To assess risk factors for HSV‐2 seropositivity, odds ratios (OR) and 95% confidence intervals (CIs) were calculated. Variables that were significant at p<0.10 in univariate analyses were selected for multivariate logistic analysis. Multivariate model variables with a probability level of p0.05 were considered statistically significant.
A total of 504 female antenatal clinic attendees participated. Excluding two samples with equivocal HSV‐2 results, 502 subjects with a mean age of 26.7 years (range 20–40) were finally included for subsequent analyses. The overall HSV‐2 seroprevalence was 10.8% (95% CI: 8.3% to 13.8%). Most subjects were married (98.2%), and 66.3% had high school education or greater. A notable proportion of women (41.2%) had migrated to Fuzhou from geographical areas within China. The participants' mean gestation period was 17.7 (SD 3.5) weeks.
The mean age at first sexual intercourse was 23.6 (SD 2.9) years. Only two women (0.4%) reported having a casual sexual partner. More than two thirds (72.4%) reported having sexual acts during pregnancy, of whom only 3% reported consistent condom use. Notably few women reported a previous history of sexually transmitted infections (1%), which included gonorrhoea or genital warts. No woman reported a history of genital herpes. Among the 54 HSV‐2 seropositive women, all but one reported no current or previous ulcerative or vesicular symptoms.
Multivariate risk factors associated with HSV‐2 seropositivity (table 11)) were older age (OR=5.14; 95% CI, 1.36 to 19.34 for >25 years), lower education (OR=5.02; 95% CI: 1.28 to 19.65 for secondary school), higher monthly income (OR=5.35; 95% CI: 1.31 to 21.83 for >2000 yuan), less frequent use of condom before pregnancy (OR=6.16; 95% CI: 1.06 to 35.69 for use in 50% of sex acts), having low abdominal pain (OR=15.83; 95% CI: 1.42 to 176.90), and having a history of abnormal vaginal discharge (OR=5.70; 95% CI: 2.28 to 14.24).
This study is the first to present type specific HSV‐2 seroprevalence data in women from eastern China. HSV‐2 seroprevalence (10.8%) is comparable to that observed in the mid‐1990s among Hong Kong residents (12.8%), yet higher than that in residents from southern China (3.2%).2 HSV‐2 seroprevalence data in addition to sexual behavioural information imply that most pregnant women in our study are susceptible to HSV‐2 infection during later stages of pregnancy, indicating an important role for counselling messages aimed to reduce the acquisition of HSV‐2 infection in late pregnancy in eastern China.
Our findings confirm associations of HSV‐2 seropositivity with older age and with lower education, as previously reported.3,4 Lower income is a risk factor for HSV‐2 in a previous study.5 In contrast, a higher monthly income in our population was associated with higher HSV‐2 seropositivity in our study population. This latter association is not well understood, although an association of a higher monthly salary with STIs was found among rural to urban migrants in Beijing.6 Interestingly, none of the HSV‐2 seropositive women reported a history of genital herpes, probably because genital herpes is commonly asymptomatic and inadequate attention is paid to genital vesicles and/or ulcers.
In several global populations HIV infection has extended from core groups, such as injecting drug users and female sex workers, into the general population through sexual transmission.7 Sexual contact has been the major route of HIV transmission in eastern China.8 HIV prevalence among pregnant women in China has reached over 1% in some areas.9 A high seroprevalence of HSV‐2 infection and other STIs among the pregnant women in the study area10 could potentially fuel a heterosexual HIV epidemic in the future.
The study was supported by grants from the National Natural Science Foundation of China (grant no 30170857) and the WHO Western Pacific in Manila (APW no WP/01/500957). We are very grateful to clinic staff, at the Fujian Provincial Maternal and Child Hospital, who recruited patients to this study. We also thank all participants in this study for their cooperation to make this study possible. Special thanks to the Jiangsu Province's Key Medical Center of Dermatology and Venereology in Nanjing, China.
Contributors: XSC and YPY were principal investigators who were responsible for the study design, data analysis, and manuscript preparation. LPC and WHW were responsible for field coordination. YHY was the laboratory based senior technician who was responsible for the laboratory testing. NTTT and JSS were responsible for inputs and comments to the study design and the manuscript preparation.
GUD - genital ulcer disease
HSV - herpes simplex virus
STIs - sexually transmitted infections
Conflict of interest: none.