Conceived and designed the experiments: HF AD KM JC HW DR RH. Performed the experiments: HF. Analyzed the data: HF. Wrote the paper: HF AD KM JC HW DR RH.
The authors have declared that no competing interests exist.
To estimate the prevalence of circumcision among young men in rural Mwanza, North-Western Tanzania, and document trends in circumcision prevalence over time. To investigate associations of circumcision with socio-demographic characteristics, reported sexual behaviours and sexually transmitted infections (STIs).
A cross-sectional survey in communities which had previously participated in a cluster-randomized trial of an adolescent sexual health intervention that did not include male circumcision in 20 rural communities.
In 2007/08, 7300 young men (age 16–23 years) were interviewed and examined by a clinician. The prevalence of circumcision by age was compared with data collected during the trial in 1998–2002. Odds ratios (OR) and 95% confidence intervals (CI) for the association of circumcision with socio-demographic characteristics, reported sexual behaviours and with HIV and other STIs were estimated using multivariable conditional logistic regression.
The prevalence of male circumcision was 40.6%, and age-specific prevalence had more than doubled since 2001/2002. Circumcised men reported less risky sexual behaviours, being more likely to report having ever used a condom (adjusted OR = 2.62, 95%CI:2.32–2.95). Men circumcised before sexual debut were at reduced risk of being HIV seropositive compared with non-circumcised men (adjusted OR = 0.50, 95%CI:0.25–0.97), and also had reduced risks of HSV-2 infection and genital ulcer syndrome in the past 12 months compared with non-circumcised men.
There was a steep increase in circumcision prevalence between 2001/02 and 2007/08 in the absence of a promotional campaign. Circumcised men reported safer sexual practices than non-circumcised men and had lower prevalence of HIV and HSV-2 infection.
Evidence from three randomized controlled trials (RCTs) has established that male circumcision reduces the risk of acquisition of HIV infection through heterosexual intercourse by 50–60%
In 2007 the World Health Organization (WHO) and the Joint United Nations Programme on HIV/AIDS (UNAIDS) declared that circumcision should be considered an important additional intervention for HIV prevention
In Tanzania, prevalence of male circumcision varies substantially by region, with the lowest prevalence in North Western and Western Tanzania (around 24%) and highest in eastern Tanzania (over 95%)
In this paper, we analyze data from a cluster-randomized trial of an adolescent sexual health intervention
Data for this study came from the MEMA kwa Vijana Trial Further Survey (MkV1FS), a cross-sectional survey carried out in 2007/08 among young people from 20 rural communities in Mwanza Region, Tanzania. The 2007/08 survey was designed to assess the long-term impact of a package of adolescent sexual and reproductive health interventions aiming to reduce the incidence of HIV, STIs and unintended pregnancies, within a cluster-randomized trial
Between July 2007 and May 2008, eligible young people for MkV1FS were identified during a household census in each of the 20 trial communities, and were invited to participate. Eligible participants had attended at least one of school years 5–7 within one of the trial communities between 1999–2002 (when the intervention was implemented most intensively). In order to capture more eligible participants, the communities, nearby schools and major migration points within the Lake Zone of Tanzania were revisited in June-July 2008.
Consenting participants for MkV1FS were interviewed at a central location in their village using standardised face-to-face questionnaires to collect information on lifestyle, health and socio-demographic factors. Circumcision status was ascertained by self-report and a physical examination by a study clinician. Blood and urine samples were collected to test for HIV, HSV-2, chlamydia, gonorrhoea and syphilis. If positive for lifetime syphilis [defined as Serodia
Data were analyzed using STATA 11.0. Unless specified otherwise, circumcision was defined using clinician-diagnosis rather than self-report.
Age-specific prevalence of circumcision was analyzed among men seen at the MkV1FS and compared with prevalence at the three previous surveys carried out during the trial. The age-specific prevalence of self-reported circumcision was compared between the 1998 survey, the 2000 survey and the MkV1FS survey (self-reported circumcision status was not asked at the 2001/02 survey), to substantiate any trends found in clinician-diagnosed circumcision prevalence. To examine whether there had been a change in age at circumcision, self-reported age at circumcision was analyzed for men currently aged 20, 21–22, 23–24 and 25+ years at the MkV1FS, restricting analysis to those circumcised at/before 20 years of age. Circumcision status for participants interviewed at both the final trial survey (2001/02) and the MkV1FS (2007/08) was analyzed to assess the number circumcised between the two surveys.
Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for associations between circumcision status and socio-demographic factors in the MkV1FS, using the clogit command. This analysis was conditioned on study community because this adjusts fully for any confounding effects of community, and allows for clustering by community, without the need for any assumptions about the distributional form of the between-community variation. A multivariable risk-factor model was built as follows: variables were added, starting with those most strongly related to circumcision in univariable analyses until no further variables significantly improved the model’s fit, assessed with the likelihood ratio test (P<0.10). For collinear variables, the variable considered a-priori to be most likely to be a risk factor (from previous research) was kept in the model.
Since effects of male circumcision on HIV and other STIs may depend on whether men were circumcised before or after sexual debut, associations with biological outcomes were examined with circumcision status in three categories: ‘non-circumcised’, ‘circumcised at/after sexual debut’ or ‘circumcised before sexual debut’, based on self-reported age at circumcision and age at sexual debut. To analyse the effects of male circumcision status on sexual behaviour, circumcision was kept as a binary variable. Conditional logistic regression was used to estimate the OR for the association between each STI outcome or sexual behaviour outcome, and circumcision status in the MkV1FS. Since the objective of this analysis was to examine the effects of a single exposure (circumcision status) rather than to build a general risk factor model, these analyses were adjusted only for age (considered an
The MkV trial and further survey were approved by the LSHTM Ethics Committee and the Medical Research Coordinating Committee in Tanzania. For the MkV trial and further survey signed informed consent was obtained from each participant on the day of the survey round. In the further survey, additional written consent from parents was obtained for participants under the age of 18 years.
In total 7,300 males were eligible and enrolled in the in the MkV1FS. Full details on the number of individuals attending the census and survey have been published previously
The male participants were aged 15–34 years (median age 22 years). Most (78.4%) belonged to the Sukuma ethnic group and most were Christian (80.7%) (
Variable | Number ofmen (%) | Numbercircumcised (%) | UnadjOR (95%CI) | Adjusted |
All Participants | 7300 (100) | 2911 (40.61) | – | – |
Group2 | ||||
Comparison | 3494 (47.9) | 1316 (38.3) | – | – |
Intervention | 3806 (52.1) | 1595 (42.6) | – | – |
Age | ||||
<21 | 2046 (28.0) | 915 (45.6) | 1 P-trend<0.01 | 1 P-trend<0.01 |
21–22 | 1977 (27.0) | 787 (40.7) | 0.77 (0.67–0.88) | 0.80 (0.69–0.93) |
23–24 | 1914 (26.2) | 730 (38.6) | 0.68 (0.59–0.78) | 0.74 (0.64–0.85) |
25+ | 1362 (18.7) | 478 (35.6) | 0.54 (0.47–0.64) | 0.63 (0.53–0.74) |
Ethnic Group | ||||
Non-Sukuma | 1575 (21.6) | 975 (63.2) | 1 P<0.01 | 1 P<0.01 |
Sukuma | 5716 (78.4) | 1934 (34.4) | 0.39 (0.33–0.45) | 0.46 (0.40–0.54) |
Religion | ||||
Christian | 5883 (80.7) | 2506 (43.3) | 1 P<0.01 | 1 P<0.01 |
Moslem | 330 (4.5) | 262 (80.6) | 6.97 (5.19–9.35) | 6.06 (4.50–8.16) |
Other Religion/No religion | 1076 (14.8) | 139 (13.1) | 0.26 (0.21–0.32) | 0.29 (0.24–0.35) |
Highest level of education reached3 | ||||
Primary or less | 5096 (69.9) | 1590 (31.8) | 1 P<0.01 | 1 P<0.01 |
Secondary or higher | 2196 (30.1) | 1319 (61.0) | 3.57 (3.18–4.01) | 3.12 (2.74–3.55) |
Occupation | ||||
Farmer | 3333 (45.8) | 884 (27.0) | 1 P<0.01 | 1 P<0.01 |
At School/University | 1740 (23.9) | 1070 (62.6) | 4.37 (3.81–5.00) | 3.67 (3.15–4.28) |
Petty Trade | 1047 (14.4) | 318 (31.0) | 1.25 (1.05–1.48) | 1.12 (0.94–1.33) |
Fisherman | 300 (4.1) | 212 (70.7) | 2.04 (1.52–2.74) | 1.73 (1.27–2.35) |
Mine Employee | 233 (3.2) | 89 (39.0) | 1.80 (1.33–2.43) | 1.51 (1.11–2.07) |
Other | 623 (8.6) | 326 (53.1) | 3.10 (2.56–3.75) | 2.48 (2.04–3.03) |
Marital Status4 | ||||
Married | 2444 (33.5) | 689 (28.6) | 1 P<0.01 | 1 P<0.01 |
Separated/Widowed/Divorced | 229 (3.1) | 77 (33.9) | 1.32 (0.96–1.82) | 1.20 (0.86–1.69) |
Never Married | 4627 (63.4) | 2145 (47.2) | 2.38 (2.12–2.68) | 2.13 (1.85–2.45) |
Adjusted for age, ethnic group and religion.
1Of 7300 surveyed, 123 males had missing data for circumcision status. 2 Odds ratios not calculable for intervention and comparison group as model is conditional on community. 38 missing values 434 missing values.
Variable | Category | Prevalence % (No/total) | UnadjOR (95%CI) | Age-adjOR (95%CI) |
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Non-circumcised | 91.4 (3894/4261) | 1 P = 0.16 | 1 P = 0.46 |
Circumcised | 90.6 (2635/2909) | 0.88 (0.74–1.05) | 1.07 (0.89–1.29) | |
|
Non-circumcised | 42.0 (1781/4245) | 1 P<0.01 | 1 P = 0.46 |
Circumcised | 38.5 (1115/2895) | 0.84 (0.76–0.94) | 0.96 (0.86–1.07) | |
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Non-circumcised | 30.5 (1183/3878) | 1 P = 0.03 | 1 P<0.01 |
Circumcised | 26.6 (698/2622) | 0.88 (0.78–0.99) | 0.83 (0.74–0.94) | |
|
Non-circumcised | 55.0 (2141/3890) | 1 P<0.01 | 1 P<0.01 |
Circumcised | 75.9 (2000/2635) | 2.52 (2.23–2.84) | 2.62 (2.32–2.95) | |
|
Non-circumcised | 27.0 (1047/3880) | 1 P = 0.24 | 1 P = 0.60 |
Circumcised | 24.8 (652/2631) | 0.93 (0.82–1.05) | 0.97 (0.85–1.10) | |
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Non-circumcised | 16.5 (569/3446) | 1 P = 0.28 | 1 P = 0.53 |
Circumcised | 14.1 (317/2252) | 0.91 (0.78–1.08) | 0.95 (0.80–1.12) | |
|
Non-circumcised | 23.1 (790/3428) | 1 P<0.01 | 1 P<0.01 |
Circumcised | 44.6 (1002/2245) | 2.88 (2.54–3.28) | 2.76 (2.42–3.14) | |
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Non-circumcised | 37.8 (783/2073) | 1 P<0.01 | 1 P<0.01 |
Circumcised | 59.8 (859/1436) | 2.63 (2.25–3.07) | 2.64 (2.26–3.09) |
Note: Missing values for reported sexual behaviours ranged from 4 to123.
Overall 2,911 males (40.6%) were judged by the study clinicians to have been circumcised. Younger age was strongly associated with circumcision, with prevalence of circumcision decreasing from 45.6% among those aged under 21 years to 35.6% of those 25 years or more (p-trend<0.0001) (
Overall 1,974 men were seen at both the 2001/02 and 2007/08 surveys, and had circumcision status recorded at both surveys. Among these, 749 were circumcised at the time of the 2007/08 survey and, 472 (63%) had been circumcised since 2002 [data not shown]. This indicates a large number of young men were circumcised between 2001/02 and 2007/08.
At the MkV1FS, reported age at circumcision was available for 2,338 men (80.3%), with median age at circumcision 16 years (IQR13–19). There was some indication that age at circumcision was younger among those aged less than 21 years compared with those aged 25 years and over (
Current age is age in 2007/08 survey and sample is restricted to those circumcised at/before 20 years of age and who were at least 20 years old at the further survey. A) <21 years (N = 314) B) 21–22 years (N = 579) C) 23–24 years (N = 476) D) 25+ years (N = 268). *Median is median age at circumcision within the current-age birth cohort, IQR is inter-quartile range.
Apart from the strong association with age, several other socio-demographic factors showed an association with circumcision in the MkV1FS (
These analyses were restricted to 6,672 (93%) of the 7,177 participants with clinician-assessed circumcision status in the MkV1FS, for whom both the reported age at sexual debut and age at circumcision were known (
Outcome | Prevalence % (No/total) | UnadjOR (95%CI) | AdjOR (95%CI) | |||
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Non-circumcised | 2.0 (85/4248) | 1 P = 0.01 | 1 P = 0.091 | |||
Circumcised at/after sexual debut | 2.2 (23/1050) | 0.94 (0.57–1.53) | 0.85 (0.52–1.40) | |||
Circumcised before sexual debut | 0.9 (12/1347) | 0.42 (0.22–0.80) | 0.50 (0.25–0.97) | |||
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Non-circumcised | 28.4 (1206/4248) | 1 P<0.01 | 1 P<0.012 | |||
Circumcised at/after sexual debut | 24.7 (259/1050) | 0.77 (0.66–0.91) | 0.78 (0.66–0.92) | |||
Circumcised before sexual debut | 19.0 (256/1347) | 0.58 (0.49–0.68) | 0.67 (0.57–0.80) | |||
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Non-circumcised | 5.7 (244/4248) | 1 P = 0.05 | 1 P = 0.723 | |||
Circumcised at/after sexual debut | 6.0 (63/1050) | 0.98 (0.73–1.32) | 1.10 (0.81–1.50) | |||
Circumcised before sexual debut | 4.3 (58/1347) | 0.69 (0.50–0.95) | 0.95 (0.68–1.33) | |||
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Non-circumcised | 3.8 (162/4248) | 1 P = 0.09 | 1 P = 0.983 | |||
Circumcised at/after sexual debut | 3.5 (37/1050) | 0.85 (0.58–1.24) | 0.98 (0.67–1.45) | |||
Circumcised before sexual debut | 2.8 (38/1347) | 0.65 (0.44–0.97) | 0.96 (0.63–1.45) | |||
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Non-circumcised | 2.3 (97/4262) | 1 P = 0.48 | 1 P = 0.381 | |||
Circumcised at/after sexual debut | 2.0 (21/1054) | 0.87 (0.53–1.43) | 0.74 (0.44–1.22) | |||
Circumcised before sexual debut | 1.8 (24/1352) | 0.74 (0.45–1.22) | 0.77 (0.46–1.29) | |||
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Non-circumcised | 0.4 (17/4262) | 1 P = 0.77 | 1 P = 0.953 | |||
Circumcised at/after sexual debut | 0.4 (4/1054) | 0.95 (0.30–3.01) | 1.13 (0.34–3.72) | |||
Circumcised before sexual debut | 0.3 (4/1352) | 0.65 (0.20–2.17) | 0.90 (0.26–3.14) | |||
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Non-circumcised | 8.8 (375/4261) | 1 P<0.01 | 1 P = 0.424 | |||
Circumcised at/after sexual debut | 9.3 (98/1053) | 1.06 (0.83–1.35) | 1.04 (0.80–1.35) | |||
Circumcised before sexual debut | 6.4 (86/1352) | 0.67 (0.52–0.88) | 0.84 (0.62–1.13) | |||
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Non-circumcised | 6.3 (269/4259) | 1 P<0.01 | 1 P = 0.064 | |||
Circumcised at/after sexual debut | 7.1 (75/1052) | 1.03 (0.78–1.36) | 1.08 (0.81–1.46) | |||
Circumcised before sexual debut | 3.9 (53/1352) | 0.54 (0.39–0.75) | 0.69 (0.47–1.00) |
1Adjusted for age and ever used a condom, 2 Adjusted for age only, 3Adjusted for age and religion, 4Adjusted for age and used condom with last sexual partner.
TPPA+ = Serodia
Missing values for STIs ranged from 10 to 41.
The 505 (7%) circumcised participants not included in this analysis of circumcision and STIs, because data on their age at circumcision and/or age at sexual debut were unavailable, tended to be younger and were more likely to be Muslim. In a sensitivity analysis in which the 505 participants were classified as having been circumcised before sexual debut, the protective effect of being circumcised before sexual debut on HIV was less strong (adjOR = 0.73 95%CI:0.44–1.21). Inclusion of these participants had little effect on the association of circumcision and other STIs.
This study suggests there was a dramatic increase in the prevalence of circumcision among young men in rural areas of Mwanza Region, Northern Tanzania, between the late 1990s and 2008 despite no active health promotion of circumcision occurring in the Region during that time period. The proportion of young men who were circumcised was 41% in 2007/08, and had more than doubled since the 2001/02 survey at all ages studied (16–23 years). The median reported age at circumcision was 16 years, with some indication of an earlier age at circumcision among the youngest birth cohorts.
The increase in circumcision prevalence is notable, particularly considering that most participants belong to the Sukuma ethnic group, who are traditionally non-circumcising, and that this occurred before active promotion of circumcision in the Region. Four independent studies carried out in rural Mwanza Region during the 1990s suggested there was a low prevalence of circumcision among adult men of 10–15%
This rise in prevalence in male circumcision in rural Mwanza Region is also supported by qualitative evidence from the 1990s
Since the results of the circumcision trials have been published, the Tanzanian government has developed a national circumcision strategic plan which aims to provide free circumcision to 2.8 million men and boys aged 10–34 years from 2010–2015
However, it is important to explore whether the observed increase in circumcision prevalence could be due to an artefact of the data, rather than a true effect. Firstly, if participants at the various surveys were not comparable, this might explain the apparent increase. However, analysis of the socio-demographic characteristics of participants in the 2001/02 and 2007/08 surveys showed no such differences [data not shown]. There were more Christians in the 2007/08 survey compared to the 2001/02 survey (80.7% versus 70.4%); self-identification as a Christian may increase with age. However, as self-identifying as a Christian did not determine circumcision status, and as there was no difference in the proportion of Muslims, this is not likely to have driven the increase.
Secondly, if study clinicians were better at recognising circumcised men at the 2007/08 survey, this could have led to an apparent increase in circumcision prevalence. Problems of clinician-assessed circumcision status have been raised, particularly regarding the difficulty in recognising partial circumcisions
Within our study cohort, circumcised men reported less risky sexual behaviour, particularly regarding condom use. In contrast, a cross-sectional study in Mbale, Uganda, found circumcised men engaged in riskier sexual behaviours; circumcised men had more extra-marital partners, and more sex in exchange for gifts or money
The associations between circumcision and STIs in this study are in line with results from other studies in Africa. Those circumcised before sexual debut had a 50% lower odds of having HIV, compared to non-circumcised men, comparable with the risk reduction of 50–60% found in circumcision trials
Our study had some limitations. First, the estimated age at circumcision was likely to be an approximation for many participants, limiting interpretation of age at circumcision. Missing circumcision status (with circumcision divided into three categories), for the 505 circumcised individuals in whom age at circumcision and/or age at sexual debut was unknown, could also potentially have biased the results, and a sensitivity analyses did demonstrate a less strong association between circumcision and HIV that was no longer statistically significant. There is also the possibility of reverse causality; the cross-sectional design could not establish the sequence of circumcision and STIs, and some men may have been circumcised as a result of having an STI, but this would tend to underestimate any protective effect.
In conclusion, the dramatic increase in circumcision prevalence over a relatively short period of time in this population, in the absence of any circumcision promotion campaigns, demonstrates that traditionally non-circumcising groups are amenable to change regarding their attitude toward circumcision. In this study, circumcised men reported safer, rather than riskier sexual behaviours, which is encouraging. However, our data were collected prior to widespread knowledge from the RCTs that circumcision can reduce risk of HIV infection and behavioural counselling prior to adult circumcision remains an integral and essential component of circumcision scale-up.