Introduction to Behavioral Surveillance Surveys
FHI's Behavioral Surveillance Surveys (BSS) provide valuable data about HIV/AIDS-related knowledge, attitudes, and behaviors. The BSS methodology is a monitoring and evaluation tool designed to track trends in HIV/AIDS-related knowledge, attitudes, and behaviors in subpopulations at particular risk of HIV infection, such as female sex workers, injection drug users, migrant men, and youth. Based on classic HIV and sexually transmitted disease (STD) serologic surveillance methods, BSS consist of repeated cross-sectional surveys conducted systematically to monitor changes in HIV/STD risk behaviors. A key benefit of the methodology is its standardized approach to questionnaire development, sampling frame construction, and survey implementation and analysis. BSS findings serve many purposes: They yield evidence of project impact, provide indicators of project success and highlight persistent problem areas, identify appropriate intervention priority populations, identify specific behaviors in need of change, function as a policy and advocacy tool, and supply comparative data concerning behavioral risks.
BSS have been conducted in more than 20 countries -- primarily in Africa and Asia -- since 1992, and their use in Latin America and the Caribbean is growing. Since 1999 they have been used in cross-border sites in Asia and Africa, where they are proving beneficial for understanding the pandemic from a regional instead of a purely country-specific perspective. In several countries multiple rounds of BSS have been implemented already, with the trend data used to formulate new programs and to adapt existing ones.
Introduction to Senegal BSS
In Senegal six official HIV cases were reported in 1986; in 1997 there were over 2,000 reported cases. However, in comparison with other countries in sub-Saharan Africa, and even countries in western Africa, the epidemic in Senegal is less severe. Adult HIV prevalence has fluctuated slightly since the early years of the epidemic, but has remained at approximately one to two percent. Prevalence is considerably higher in some high-risk groups, such as female sex workers (33.3 percent infected in the Ziguinchor region in 1997).
From 1992 through 1997, four diverse regions of Senegal -- Dakar, Kaolack, Thies, and Ziguinchor -- were the focus of HIV prevention efforts. Since then, these efforts have been expanded to include other parts of the country. The first wave of BSS was conducted in these four regions due to the level of effort and attention they had received through prevention interventions. Findings from BSS one prompted researchers to add a number of subpopulations before implementing BSS two, which included all ten provinces and a total of ten subpopulations from both genders and from diverse backgrounds and occupations. Data on the three subpopulations surveyed in both waves are presented in this report. A third wave of BSS is currently planned for 2000.
Study Design and Methodology
Study population
Data on high-risk subpopulations provide information on the groups that have the greatest impact on HIV and STD epidemics. For this reason, subpopulations for BSS primarily consist of groups such as female sex workers (FSWs) who are at high risk of becoming infected and passing the infection onto others. Other subpopulations consisting of individuals who have significant sexual contact with members of both high- and low-risk groups are considered "bridge" groups. Long-distance truckers or miners, who may have contact with non-regular partners and FSWs while they are away from their regular partners for extended periods of time, are examples of bridge populations. Low-risk groups are more broadly defined subgroups of general populations with varying sociodemographic characteristics, such as workers and students.
The first wave of BSS in Senegal included female and male students, female sex workers, and informal sector workers. The second wave included female and male students, female sex workers, apprentices in the informal sector, young female domestic workers, male and female workers from the formal sector, truck drivers, prisoners, and female NGO members (a low-risk group serving as a proxy for the general population). Results for the three subpopulations included in both waves one and two are presented here.
|
Senegal BSS Subpopulation Definitions |
|
Male students
Secondary school students (majority ages 15 to 19 years old)
Female students
Secondary school students (majority ages 15 to 19 years old)
Female Sex Workers (FSWs)
Female sex workers registered with the government |
Sample size
The number of respondents for each group was determined based on the estimated level of key risk behaviors (such as percentage using condoms with non-regular partners) and the degree of confidence required to detect a significant change in behavior over time. The sample size for youth increased considerably for the second BSS because, based on the outcomes of the first wave, researchers decided to expand the geographic scope of the sample, necessitating an increase in sample size (see Table 1). While the geographic scope of sampling was also enlarged for FSWs, their numbers did not increase as dramatically due to their small overall numbers in some of the regions added in BSS two.
Table 1. Subpopulations, Sample Sizes, and Study Sites
| Subpopulations |
Sample Size |
Survey Sites |
| 1997 |
1998 |
1997 |
1998 |
| Male students |
444 |
1181 |
Dakar, Kaolack, Thies, and Ziguinchor provinces |
Dakar, Kaolack, Thiés, Ziguinchor, Saint-Louis, Louga, Tambacounda, Fatick, Diourbel, and Kolda provinces |
| Female students |
478 |
1179 |
| Female sex workers (FSWs) |
449 |
681 |
Sample design
The size of each subpopulation within selected towns was estimated and a two-stage sampling procedure was used to select respondents. Clusters were selected using probability proportional to size (PPS) in the first stage and respondents were selected randomly from those clusters in the second stage. During the first stage, a list or sampling frame was prepared to provide the basis for selecting clusters. Schools were used as clusters for male and female students, and bars and STD clinics were used as clusters for FSWs.
Teams of field staff received in-depth training in data collection methods and used standardized data collection tools. Each data collection team consisted of trained interviewers and supervisors, who closely monitored the fieldwork.
Youth Results
Sociodemographics
Eighty-one percent of females in wave one and 79 percent in wave two were ages 15 to 19 years. The same respective proportions of males ages 15 to 19 were sampled in wave two. A further 14.6 percent of females in wave one and 16.9 percent in wave two were 20- to 24-years-old; males in this age group were similarly represented, with 17.1 percent in wave one and 16.3 percent in wave two. The remaining students were younger than 15 or older than age 25. Married females comprised 1.5 percent of those surveyed in wave one and 2.5 percent in wave two. The remaining females and all males surveyed were unmarried.
Trends in BSS indicators
Knowledge of STDs
Sixteen percent of female students were able to name two or more STD symptoms in females; this figure had increased to 21.3 percent by wave two (figure 1). For males, the ability to correctly name two STD symptoms in males dropped 4 percentage points, from 21.4 percent to 17.4 percent. The majority of both males (57.6 percent) and females (59.3 percent) could not identify any gender-specific symptoms of STDs in wave two, down from 60.6 percent of males and 65.3 percent of females in wave one.
Figure 1. Knowledge of gender-specific STD symptoms
Knowledge of HIV/AIDS
Over 95 percent of all students surveyed were able to correctly identify two methods of preventing HIV transmission during both waves, with 100 percent of females able to identify two or more methods in wave two. At the same time, in both waves approximately one-quarter of males and one-third of females reported that transmission can be caused by using the same toilet as someone who is HIV-positive and by mosquito bites.
Behavioral Indicators
The majority of females in both waves had never had sexual intercourse, and that percentage increased from almost 88 percent in wave one to almost 95 percent in wave two. On the other hand, approximately one-third of male students had had sexual intercourse, and this level remained stable across the two survey waves (34.2 percent in wave one and 35 percent in wave two). Since the level of sexual activity was low among the females surveyed, the remainder of this section will focus on males.
Figure 2. Number of non-regular partners for male youth
Apparent changes in risk behavior among male youth were ambiguous. While the percentage of men reporting non-regular partners increased between waves one and two (figure 2), "always"' use of condoms with these non-regular partners also increased over the same period (figure 3). Specifically, the percentage of males reporting non-regular partners increased from 31.3 percent in wave one to 44.8 percent in wave two. ("Non-regular partners" are sexual partners who do not live with and are not currently married to the respondent and with whom the respondent has not been sexually active for longer than the past 12 months). Those having two or more non-regular partners increased from 14.1 percent in wave one to 17.4 percent in wave two.
The majority of males in both waves reported consistent use of condoms with their non-regular partners. "Always" use of condoms with non-regular partners increased between waves one and two from 54.3 percent to 63.6 percent.
Figure 3. Male youth condom use with non-regular partners
In both wave one and wave two, fewer than 3 percent of sexually active respondents reported sex with a female sex worker.
Female Sex Worker (FSW) Results
Sociodemographics
Table 2 provides selected demographic characteristics of FSWs. In both waves one and two, only approximately 15 percent of respondents were younger than 25 years old, while approximately one-half were between the ages of 25 and 34 years and an additional 20 percent were ages 35 to 39. The proportion of women without any schooling was 42.4 percent in wave one and 51.5 percent in wave two. Of women who had been formally educated, approximately one-third (36.7 percent in wave one and 31.9 percent in wave two) had only a primary school education. The majority of FSWs were divorced (57.3 percent in wave one and 58.3 percent in wave two), and 38 percent in wave one and 33.5 percent in wave two were single.
Table 2: Basic Demographics, Female Sex Workers
| Variable |
1997 |
1998 |
| Sample size (n) |
449 |
681 |
|
Age (years)
< 20
20 -- 24
25 -- 29
30 -- 34
35 -- 39
40 -- 49
50+
Missing |
|
|
| 1.6 |
2.3 |
| 14.1 |
10.4 |
| 27.1 |
25.6 |
| 22.9 |
23.3 |
| 18.0 |
19.7 |
| 12.7 |
16.5 |
| 3.0 |
2.1 |
| Education |
|
|
| No school (illiterate) |
42.4 |
51.5 |
| Primary |
36.7 |
31.9 |
| Junior high level / + |
18.3 |
15.1 |
| Literate in Arabic or other languages |
2.7 |
1.5 |
| Marital status |
|
|
| Single |
38.0 |
33.5 |
| Married |
1.1 |
1.5 |
| Widowed |
3.6 |
6.7 |
| Divorced |
57.3 |
58.3 |
Trends in BSS indicators
Knowledge of STDs
In wave two FSWs were better able to identify two or more correct STD symptoms in women and men (44.4 percent and 36 percent, respectively), than in wave one (40.7 percent in women and 30.7 percent in men). Also, fewer FSWs were unable to identify any symptoms in wave one (35.3 percent in women and 41 percent in men) in comparison with wave one, where 42.4 percent of FSWs could not correctly identify any symptoms in women and 46.2 percent could identify no correct symptoms in men (figure 4).
Figure 4. FSW knowledge of STD symptoms
Knowledge of HIV/AIDS
When provided with a list of possible methods of HIV prevention, almost all respondents were able to name at least two correct methods of preventing HIV transmission (91.1 percent in wave one and 98.5 percent in wave two). At the same time, however, beliefs about incorrect means of prevention continued to be prevalent across the two waves of behavioral surveillance (figure 5).
Figure 5. Percentage of FSWs identifying popular
misconceptions as correct methods of prevention
Behavioral Indicators
The majority of FSWs in both wave one (54.4 percent) and wave two (55.2 percent) experienced first intercourse between ages 15 and 19 years, and approximately a quarter of women in both waves had experienced intercourse before the age of 15 (figure 6).
Figure 6. FSW age at first intercourse
Decreases of less than 2 percentage points in condom use at last sex were reported between waves one and two for all types of partners; however, these decreases were not significant. In contrast, reported frequency of condom use with clients improved, although again, the changes were small across the two waves. Between waves one and two, "always" condom use increased from 90.2 percent to 94.5 percent with regular clients, but decreased from 71.2 to 51.4 percent with non-clients (figure 7). Rates of "always" condom use with one time-clients were high. Almost 98 percent of FSWs reported always using condoms with one-time clients in wave two, up from 93.9 percent in wave one.
Figure 7. FSW frequency of condom use by partner type
Summary of Findings
Only two data points were available at the time of this report, while at least three data points are necessary to demonstrate a trend. Although it is not possible to draw conclusions about changes in knowledge and behavior related to HIV/AIDS/STD at this time, summarized here are highlights from the Senegal BSS waves one and two:
Youth
- More than half of the youth surveyed do not know gender-specific symptoms of STDs.
- Nearly all high school youth know at least two methods of HIV/AIDS prevention, and knowledge of methods improved between waves.
- Almost all the females and two-thirds of the males surveyed had never had sexual intercourse. Rates changed little between waves one and two.
- The percentage of sexually active males having non-regular partners over the previous 12 months increased from nearly one-third to nearly one-half between waves one and two.
- More than half of males with non-regular partners reported always using condoms with those partners, with "always" condom use increasing between waves one and two.
Female sex workers
- Approximately 40 percent of FSWs in both waves could not correctly identify any symptoms of STDs in men or women.
- Knowledge of two or more methods of HIV prevention improved between waves, with more than half of FSWs able to name at least two methods by wave two.
- More than half of FSWs surveyed experienced first intercourse between the ages of 15 to 19.
- "Always" condom use with regular clients was over 90 percent during both waves.
Technical Guidelines
For more information, see the following technical guidelines:
UNAIDS and Family Health International, May 1998. Meeting the Behavioural Data Collection Needs of National HIV/AIDS and STD Programmes.
Discusses behavioral data collection needs by different epidemic state. Reflects recent thinking about the best use of resources in behavioral data collection in the context of second generation surveillance.
Family Health International, June 2000. Behavioral Surveillance Surveys (BSS): Guidelines for Repeated Behavioral Surveys in Populations at Risk for HIV.
Provides how-to information that includes identifying priority subpopulations, developing sampling frameworks and approaches, and suggesting analysis and dissemination strategies. Also includes sample questionnaires.
UNAIDS and WHO, 2000. Guidelines for Second Generation HIV Surveillance.
Provides an overview of the principal issues that need to be considered in strengthening surveillance systems and increasing their utility. Suggests priority approaches for the various epidemic states.
Acknowledgments
The Senegal BSS were executed by:
Institut Supérieur Africain pour le Développement de l'Entreprise (ISADE) and the Cabinet d'Etudes et de Recherche (HYGEA)
Administered by:
Senegal National AIDS Control Program and the Ministry of Public Health
With technical assistance from:
Family Health International
Funded by:
United States Agency for International Development (USAID), the United Nations Development Programme (UNDP), and the United Nations Children's Fund (UNICEF)
This executive summary is based on the following reports:
Comparison of BSS 1997 and 1998 for Students and Female Sex Workers, 1998.
Senegal Behavioral Surveillance Survey, 1998.
