Possible reasons for an increase in the proportion of genital ulcers due to herpes simplex virus from a cohort of female bar workers in Tanzania

Objectives: To determine trends in the prevalence and aetiological
distribution of genital ulcer syndrome (GUS) in a cohort of female
bar workers and to assess factors associated with these
trends.Methods: An open cohort of 600 women at high risk of HIV and
sexually transmitted infection (STI) was offered screening and
treatment for STI at 3-month intervals. The prevalence of GUS and
associated aetiological agents (Herpes simplex virus (HSV),
Treponema pallidum and Haemophilus ducreyi) were monitored over 27
months through clinical examination, dry lesion swabbing and
multiplex polymerase chain reaction. The effects of HIV status and
other factors on the prevalence trends of STI were
assessed.Results: A total of 753 women were recruited into the
cohort over 10 examination rounds. At recruitment, the
seroprevalence was 67% for HIV and 89% for HSV type 2 (HSV-2).
During follow-up, 57% of ulcers had unknown aetiology, 37% were due
to genital herpes and 6% to bacterial aetiologies, which
disappeared completely in later rounds. The absolute prevalence of
genital herpes remained stable at around 2%. The proportion of GUS
caused by HSV increased from 22% to 58%, whereas bacterial causes
declined. These trends were observed in both HIV-negative and
HIV-positive women.Conclusions: The changes observed in the
frequency and proportional distribution of GUS aetiologies suggest
that regular STI screening and treatment over an extended period
can effectively reduce bacterial STI and should therefore be
sustained. However, in populations with a high prevalence of HSV-2,
there remains a considerable burden of genital herpes, which soon
becomes the predominant cause of GUS. Given the observed
associations between genital herpes and HIV transmission, high
priority should be given to the evaluation of potential
interventions to control HSV-2 either through a vaccine or through
episodic or suppressive antiviral therapy and primary prevention.