O1-S04.05 Incidence and prevalence of sexually transmitted infections among school students in the Eastern Cape, South Africa
Authors: Radebe F , Jemmott J , Klopper A , Jemmott L , O'Leary A , Ngwane Z , Carty C , Tyler J , Maseko V , Lewis D 
Published: July 2011

Background

Although STIs are an important co-factor for HIV acquisition, few community-based STI prevalence/incidence data exist for youth in South Africa.

Methods

School students (n=1057), enrolled in a cluster-randomised intervention trial in the Eastern Cape, were tested for STIs at the 42 (42M) and 54 (54M) month follow-up visits. Students filled in questionnaires, provided blood for herpes simplex type 2 (HSV-2) serology (HerpeSelect IgG, Focus Diagnostics) and urine to test forNeisseria gonorrhoeae(NG),Chlamydia trachomatis(CT) andTrichomonas vaginalis(TV) (Aptima Combo 2 and Aptima TV, GenProbe). Positive NG/CT/TV results were confirmed by other assays (Aptima NG, Aptima CT, Gen-Probe;T vaginalisReal-TM, Sacace Biotechnologies). Students with NG/CT/TV received treatment and partner follow-up; those with HSV-2 infection were counselled. STI prevalence was determined by gender at each visit; overall incidence was estimated using results for all students attending both visits and also for a subgroup who reported ever having had vaginal intercourse. Descriptive statistical analysis was performed and associations investigated with the χ2test.

Results

959 (91%) and 977 (92%) students tested for STIs at 42M and 54M, respectively. The students' mean age (SD) was 15.8 (1.25) years at 42M and 16.8 (1.25) years at 54M. At 42M, 149 (15.5%) had curable STIs and 67 (7.0%) had HSV-2 infection. At 54M, 154 (15.8%) had curable STIs and 104 (10.7%) had HSV-2 infection. All curable STIs were treated. Females had a higher prevalence of all pathogens at both visits (p<0.001 for all, Abstract O1-S04.05 table 1). Overall annual incidence rates (per 1,000, 95% CI), based on results of the 934 (96%) students who attended the 42M/54M visits (934 urine, 931 serology tests), were substantially higher in females compared to males [males: GC 18.4 (8.7–36.6), CT 73.7 (52.4–102.5), TV 0.0 (0.0–10.6), HSV-2 28.6 (15.9–59.9); females: GC 76.0 (55.6–102.8), CT 184.0 (152.7–220.4), TV 40.0 (25.7–61.3), HSV-2 64.4 (44.9–91.3)]. Incidence rates were also calculated for students (311 females, 66%; 334 males, 77%) who reported ever having had vaginal intercourse (Abstract O1-S04.05 table 1). Compared to overall rates, females had significantly higher rates for each STI (GC/CT, p<0.001; TV, p =0.027; HSV-2, p =0.015); this was not the case for males.

Abstract O1-S04.05 Table 1

Prevalence and incidence data for East London students. (Note: Blood testing was declined by 2 students at 42 months and 4 youth and 54 months. Data were missing on vaginal intercourse for a further 3 students at 54 months)

GenderNo. of evaluable youthMean age in years (SD)StatisticNeisseria gonorrhoeaeChlamydia trachomatisTrichomonas vaginalisNo. of evaluable youthHerpes simplex type 2Prevalence% (95% CI)% (95% CI)% (95% CI)% (95% CI)Male44616.1 (1.25)42 month prevalence0.90 (0.26 to 2.37)3.14 (1.83 to 5.25)0.90 (0.26 to 2.37)4443.15 (1.84 to 5.27)Female51315.5 (1.17)42 month prevalence8.77 (6.60 to 11.56)17.93 (14.85 to 21.50)7.21 (5.26 to 9.81)51310.33 (7.97 to 13.28)Male45717.1 (1.27)54 month prevalence1.75 (0.83 to 3.48)7.22 (5.16 to 9.99)0.00 (0.00 to 1.00)4555.05 (3.36 to 7.50)Female52016.5 (1.14)54 month prevalence7.69 (5.68 to 10.33)18.27 (15.18 to 21.83)4.04 (2.62 to 6.13)51815.64 (12.75 to 19.03)Incidencenew case per 1000 (95% CI)new case per 1000 (95% CI)new case per 1000 (95% CI)new case per 1000 (95% CI)Male43417.1 (1.24)Overall incidence at 54 months18.4 (8.7 to 36.6)73.7 (52.4 to 102.5)0.0 (0.0 to 10.6)41928.6 (15.9 to 49.9)Female50016.5 (1.13)Overall incidence at 54 months76.0 (55.6 to 102.8)184.0 (152.4 to 220.4)40.0 (25.7 to 61.3)45064.4 (44.9 to 91.3)Male33417.2 (1.22)Incidence at 54 months among those reporting previous vaginal intercourse18.0 (7.3 to 39.6)77.8 (53.3 to 112.0)0.0 (0.0 to 13.7)32218.6 (7.6 to 41.0)Female33116.6 (1.06)Incidence at 54 months among those reporting previous vaginal intercourse108.8 (79.3 to 147.2)244.7 (201.4 to 293.9)54.4 (34.2 to 84.8)29687.8 (60.2 to 126.0)

Conclusions

This community-based screening study demonstrates an extremely high STI burden among youth in the Eastern Cape Province of South Africa.