Abstract:
Herpes Simplex Virus type 2 (HSV-2) has public health importance as a leading cause
of genital ulcers, a co-factor in HIV-1 acquisition and transmission and as a cause of
neonatal herpes infections. Little is known of the epidemiology and burden of disease
in Coastal Kenya. The objective of this study was to describe the serological
prevalence of HSV-2 infection, factors associated with infection and the potential risk
for vertical transmission among women aged 15-34 years. Plasma samples of 826
women who participated in an HIV-1 survey in Kilifi in 2004 were screened for HSV2 IgG antibodies using HerpeSelect ELISA. The sample comprised 563 women
selected randomly from a demographic surveillance system (DSS) and 263 women
who presented for voluntary counseling and testing (VCT). Predictors for HSV-2
seropositivity and HIV-1/HSV-2 co-infection were determined using multivariate
logistic regression. The incidence of maternal HSV-2 infection and risk of neonatal
herpes were estimated by a simple catalytic model fitted to age-seroprevalence data.
The overall HSV-2 seroprevalence was 36% (296/826), and differed between DSS and
VCT recruits (32% vs. 44%, P<0.001). The HIV-1 prevalence was 8% and 12% (P =
0.12) among the DSS and VCT recruits, respectively. Independent risk factors for
HSV-2 infection in all women were: older age (30-34 years; odds ratio (OR) 10.5,
95% confidence interval (CI): 5.2 - 21.0), recruitment from VCT (OR 1.5, 95% CI: 1.1
- 2.1), history of genital ulcers (OR 1.7, 95% CI: 1.2 - 2.3) and HIV infection (OR 2.7,
95% CI: 1.6-4.6). Education beyond primary (OR 0.7, 95% CI: 0.5 - 0.9) was
inversely associated with HSV-2 infection. Predictors for HSV-2/HIV co-infection
were genital ulcers (OR 2.4, 95% CI: 1.4 – 4.9) and presence of other sexual
transmitted infections (OR 2.8, 95% CI: 1.3 – 5.9). In the DSS sample, estimated
HSV-2 incidence was 6 cases (95% CI: 5.3 – 6.8) per 100 women per year, 21 cases
(95% CI: 20-22) per 1,000 pregnancies per year and 41 neonatal cases (95% CI: 39-
42) per 100,000 births per year. In conclusion, HSV-2 prevalence in this population is
similar to the national observed prevalence among women. HIV-1 is a strong predictor
for HSV-2 infection. The rate of HSV-2 transmission is rapid following the onset of
sexual activity. Nevertheless, the burden of neonatal HSV-2 can be predicted to be
low.
