Urban–rural and socioeconomic variations in lifetime prevalence of symptoms of sexually transmitted infections among Bangladeshi adolescents

Sexually transmitted infections (STI), including acquired immunodeficiency syndrome, are influenced by a number of biological and medical factors on the one hand and geographical, sociocultural or political factors on the other [[1],[2]]. Globalization, involving development of trade and movement of both goods and humans across countries and territories, is also being postulated as a major factor in the spread of infectious diseases worldwide [[3]]. In Bangladesh, nearly one-third of the population is in the 10 to 24-year age group [[4]]. The vast majority of this section is unaware of the risk of STIs and human immunodeficiency virus (HIV). The situation in Bangladesh, as elsewhere in the world, is getting critical as adolescents usually do not have access to basic information on sexual and reproductive health (SRH), skills in negotiating sexual relationships, and access to affordable SRH services [[5],[6]]. Although PIACT Bangladesh, a non government organization, has worked with the National Curriculum and Textbook Board (NCTB) of Bangladesh to incorporate HIV modules in the curriculum of grades 6 to 10, but unfortunately this issue has not yet been included in the curriculum [[7],[8]]. Several studies revealed that a section of adolescents tend to engage in high-risk activities such as visiting commercial sex workers without using condoms, and thus suffer from STIs as a consequence [[9],[10]]. It has been reported that STIs substantially facilitated the rapid and extensive transmission of HIV infections [[11]]. However, this issue is being given high priority in Bangladesh [[12],[13]].

The World Health Organization has estimated that in 1999 there were 340 million incidences of STIs (gonorrhoea, chlamydial infection, syphilis, and trichomoniasis) among the 15-49-year-age group in the world, the highest concentration in Asia [[14]]. STIs are currently recognized as the major health and economic burdens for many developing and developed countries [[14],[15]]. Thus, the control of STIs is important not only to prevent complications from these infections but also to prevent HIV transmission. In Bangladesh, several studies have assessed adolescents knowledge [[9],[10],[16],[17]] and estimated the seroprevalence of STIs and reproductive tract infections (RTIs) in both the general population and the high-risk groups [[18]-[21]]. However, there is no nationwide study on the prevalence of lifetime symptoms (persons known to have had the disease for at least part of their life) [[22]] of STIs. Therefore, this study aims to estimate the prevalence of self-reported lifetime symptoms of STIs, and the impact of socioeconomic, demographic and urban–rural factors on the risk of STIs among the 12 to 24-year age group of population in Bangladesh.

During the 5-month survey, 16,616 rural and 5,040 urban households were visited (Figure 1). Of these, 11,721 (71%) rural and 3,650 (72%) urban adolescents aged 10–24 years were eligible for this survey. Of them, 11,384 (97%) rural and 3,558 (98%) urban adolescents agreed to participate. Of the participating adolescents, 9,016 from rural and 2,970 from urban areas were allowed by their family to be interviewed regarding sexual issues. Thus, 5,119 male (97.9%) and 6,867 female (96.6%) adolescents participated in the survey.

Probability estimation

The probability of lifetime prevalence of STI symptoms as outcomes of the effect of various combinations of factors is shown in Figure 2. The probability was low among 12–14 years old female adolescent household workers with no schooling or having primary education, from either poorest or rich living in urban areas (p = 0.02) (Figure 2). The highest prevalence was found for the 20–24 years old males with higher education and income, from the middle socioeconomic group living in rural areas (p = 0.31).

This study shows that the self-reported lifetime prevalence of STI symptoms among adolescents in Bangladesh is high and varies by their place of residence, and socioeconomic and demographic factors. This information is useful for the policy-makers to develop strategies to prevent and control sexually transmitted diseases.

This study confirms a high lifetime prevalence of STI symptoms is more prominent among males. It also contradicts the misconception, found in one report, that STI prevalence is higher in women, which is possibly due to lack of awareness and practice of personal hygiene [[30]]. Highest prevalence was found in currently married older adolescents (20–24 years) living in rural areas . Studies in Bangladesh and neighbouring countries have shown varying prevalence rates of STIs in the general population as well as in high-risk groups [[18]-[20]]. Bogaerts et al. [[20]] detected a low prevalence of Neisseria gonorrhoea and chlamydia infections (0.5% and 1.9%) among urban female clients in a basic health-care clinic in Dhaka, while Sabin et al. [[18]] reported a higher sero-prevalence of current STIs (10.4% in 15 to 54-year old men and 6.9% in 15 to 40-year old women) among slum dwellers in Dhaka, Bangladesh. Similar studies in neighbouring countries reported a higher prevalence than what we found in this study. In Hainan [[31]], China, Xia et al. found that the lifetime prevalence of STI symptoms among the 18 to 49-year old married rural women was 39%. The higher prevalence is possibly partly explained by that they were older than the adolescents we studied, and thus had had a longer exposure time. In an urban-based cross-sectional study of residents from low-income communities in Chennai, India [[32]], the prevalence for self-reported STI symptoms was 16%, higher than that of our study. Reasons for varied results could be due to differences in sampling method, measuring instruments, manner of queries, and way of filling questionnaires.

The prevalence in high-risk groups is higher. A cross-sectional study of 18–30 years old street-based female sex workers in Dhaka by Rahman et al. detected 33% prevalence of syphilis and 46% prevalence of Neisseria gonorrhoea/chlamydia [[33]]. Another cross-sectional study estimated the prevalence of syphilis and Neisseria gonorrhoea/chlamydia at 8.5% and 58% respectively in 18–25 years old hotel-based female sex workers in Dhaka [[21]].

Using the Bangladesh adolescents survey 2005 dataset, Gani and Ahmed [[17]] showed that the adolescents grew up without knowing the facts of SRH, which is prominent among the low educated rural adolescents living in poor households. This pattern is also confirmed in this analysis. This might be because the cultural norms forced the parents/guardians to feel embarrassed or ashamed to discuss these issues with their adolescent children, and that the media is overlooking the issue simply as it involves the issue of sex [[8],[21]]. Consequently most of them have had a limited access to reliable and complete SRH information, which is making the adolescents vulnerable. Therefore, the cultural behaviour bias might have been associated with this disease.

Limitations of this study include non-response bias (3% for all selected adolescents) as it happened against the backdrop of a huge temporary migration of 15 to 24 years old male respondents, particularly for foreign employment [[34]]. The interviewers found it difficult to determine the exact age of the respondents although the events calendar was used to obtain best estimates. As such some errors cannot be ruled out. The lowest rate of STI symptoms among females might be due to silent infections or any other unknown reasons relating to social stigma of STI. Another limitation is that the self-reported symptoms are not serologically confirmed as found in some other studies [[31],[32]], and, thus non-STI genital symptoms may have been included in the results.

Strengths of this first nationwide adolescents survey is that it permits to draw conclusions regarding the whole country by age, sex and place of residence. Furthermore, the size of the study facilitates precise point estimates with narrow confidence intervals. As the sampling design is similar to the 2004 BDHS [[25]], it allows comparison of some background indicators for testing data reliability and validity of this study. For example, the male/female ratio of this study is consistent with that of the national dataset (0.80 in BAS 2005; 0.85 in BDHS 2004) [[25]].

The high self-reported lifetime prevalence of STIs among adolescents reflects the varying living conditions in urban and rural areas, and demographic and socioeconomic characteristics. Older male adolescents with higher education from the middle class socioeconomic background living in rural areas are especially at risk of having the STIs. It thus indicates that STIs are endemic in the entire country. Further research is needed to fully understand the epidemiology of STI in Bangladesh. A prerequisite is a cheap and reliable screening instrument to be able to quickly confirm symptomatic cases. Further research is also needed to identify effective intervention to reduce the STI prevalence in Bangladesh.

Simpler and cheaper mode of screening and case finding tools are urgently required for a clear understanding of the epidemiology of STIs in Bangladesh. Therefore, this simple, inexpensive, and replicable method could also be used to gauge the distribution of self-reported lifetime symptoms of STIs in other countries and, thus, create the basis for a thorough aetiological research on overall STIs and appropriate interventions to address the problem.