| BackgroundThe human immunodeficiency virus (HIV/AIDS) epidemic has become a major global public health and social problems in many countries. AIDS has become one of the most serious infectious diseases to human life and health, and increasingly contributes to the erosion of civil order and economic growth. Although the AIDS epidemic in China is still in the overall low prevalence, there are significant geographic variations in HIV prevalence in difference Province, some specific groups have emerged high HIV prevalence. The epidemic is spreading from high-risk groups to the general population. Sexual contact has become the dominant modes of HIV transmission, more than 70% were infected through sexual contact in the newly reported HIV/AIDS cases in 2009. The proportion of sexual contact has also been increasing in the newly reported HIV/AIDS cases in Shandong Province,70.9% were infected through sexual contact in the newly reported HIV/AIDS cases in 2009. The increasing proportion of sexual transmission has important implications. According to the experience of African countries, when the sexual transmission became the main mode of HIV transmission, then the epidemic will rise rapidly. Therefore, the control of AIDS through sexual transmission is important.Sexual transmission becoming a major mode of transmission was associated with the widespread presence of commercial sex trade, female sex workers (FSWs), as a special bridge groups, plays an important role in the transmission process. Hence, to understand their status of HIV infection and related behaviors will have importance meanings to control the HIV/AIDS epidemic. Since 1995, HIV serological surveillance among female sex workers was started to implement in Shandong Province, which had provide lots of information about the status of HIV prevalence among FSWs, while, it has also exposed the shortcomings of the serological surveillance, which does not reflect the social and behavioral factors of AIDS epidemic, those risk factors associated with HIV/STD infection and high risk behaviors are not clear. At the same time, there are many potential risks to spread the epidemic in Shandong province, such as increasing STD prevalence, increasing mobility population, broader sexual freedom with more tolerant views, concurrent with the increasing of commercial sex in Shandong Province. In addition, the World Health Organization (WHO) reported that methamphetamine use will become a major public health issue in the world, and will spread to replace heroin in some extent in Asia and other countries. But for now, Methamphetamine use and related risk factors has been only reported among MSM in western countries, and few studies have investigated methamphetamine use among FSWs. Thus, behavioral investigation among FSWs should be conducted in Shandong province to understand their status of HIV/STD prevalence and risk factors. Therefore, three consecutive cross-sectional surveys with consistent recruiting procedures were conducted among FSWs across 3 cities from 2006 to 2008, in order to explore their status of HIV/STD infection and behavioral characteristics, to understand HIV-related behavior change trends and assess their potential roles in the HIV epidemic, which will be helpful for HIV/AIDS control in the future.Female sex workers is also called hidden populations, are a sensitive group, they don't want to reveal their identity in public for the reason of discrimination. It is a continuing challenge for researchers to get a representative sample among those hidden populations. Therefore, exploring the effective sampling method will be special meaning for AIDS control.Respondent driven sampling is a new form of chain referral sampling method to sample a hidden population, it also claims to produce an unbiased indicator for population estimates through special statistical soft to analyze the variability of indicators and thereby compute standard errors for population estimates. RDS has been applied in many research programs to sample hard-to-reach and hidden populations such as IDUs and MSM, however, the RDS method has not been widely applied for recruiting FSWs. This study was conducted to recruit FSWs using RDS method to explore and evaluate application of respondent driven sampling in the recruitment of female sex workers, and to investigate demographic characteristics, their status of HIV/STD infection, their social network information, and high risk behaviors of female sex workers, and offer scientific evidence for developing intervention strategy.Objects1. To understand HIV/STD prevalence and risk factors among female sex workers.2. To understand HIV-related behavioral characteristics and risk factors among female sex workers.3. To understand HIV/STD prevalence and behavioral change trends among female sex workers, and provide information for the HIV/AIDS epidemic estimation.4. To evaluate intervention effect, and provide scientific basis for making intervention strategy.5. To explore and evaluate application of respondent driven sampling in the recruitment of female sex workers, and provide reference for future research in this population.Methods1. Three consecutive cross-sectional surveys with consistent recruiting procedures were conducted among FSWs across 3 cities in 2006,2007 and 2008, respectively. Questionnaire-based interviews provided demographic and social information, sexual behaviors and condom use, drug use behavioral information, HIV knowledge and perceptions, ever had STD-related symptoms, and ever received HIV-related services. Blood samples were collected from all participants to test their status of HIV and syphilis prevalence. Survey data were recorded with EpiData software. SPSS11.0 software was applied for all statistical analyses, such as mean, variance analysis, chi-square test, stratified analysis, univariate and multivariate Logistic regression analysis. 2. Respondent driven sampling was used to recruit female sex workers, seven seeds were recruited through the local key informants to participate in the study. After the seeds completed the interview, each of them was given three coupons for recruiting their peers into the study. Three coupons for referring peers were given to the participants when they finished the interview and the sample collection. The desired sample size will be gotten by this chain-referral sampling method. All new recruits were offered a dual incentive, one for completing the interview and on for recruiting. RDSAT, NetDraw and SPSS 11.5 software were applied for data analysis.Results1. The results of high risk behavioral change research among FSWs in Shandong Province3,460 participants in total were investigated in the three years, of the participants, 2 were HIV-infected (1 in 2006 and 1 in 2008).54.6% were 20-24 years of age,75.9% were unmarried, and 52.0% coming from local province. The proportion of FSWs coming from local province was increasing, there was a significant difference (P<0.001), and education level of FSWs was increasing with 14.7% received high school or high education in 2006 and 22.5% in 2008.The age of first sex experience was from 11 to 29 years old, and the age of first commercial sex was from 12 to 45 years old.47.5% started sex work<20 years of age, 46.0% had<2 years of sex work experience, and 57.8% had≥7 paying clients in the past week.72.3% reported condom use with client in the last sex behavior, there was a significant difference compared 2008 to 2006 (P<0.001). The rates of consistent condom use for FSWs with clients in the last month were 32.6%,53.6%, and 48.2%, respectively. there was a significant difference(P<0.001).45.3% reported condom use with regular partners in the last sex behavior, there was a significant increase compared 31.1% in 2006 to 57.5% in 2008(P<0.001). The rates of consistent condom use for FSWs with regular partners in the last month were 18%,17.6%, and 40.5% in 2006,2007, and 2008, respectively, there was a significant difference (P<0.001).45.6% of the FSWs reported ever appear STD-related symptoms, but there wasn't a significant difference in the three years (P>0.05), of which 72.6% will choose hospital to treatment, the proportion was increasing from 38.1% in 2006 to 92.1% in 2008, there was a significant difference (P<0.001). Some of FSWs may choose to treat by buy medicine from shopping, but the proportion decreased, from 54.7% in 2006 to 32.5% in 2008, the difference was significant (P<0.001).The HIV/AIDS knowledge scores≥6 among FSWs were 75.3% in 2006, 83.8% in 2007, and 84.6% in 2008, the major mode for FSWs to access HIV-related knowledge was free promotional materials, accounting for 80.1%, followed by television, accounting for 71.8%. The proportion of FSWs access HIV-related knowledge channels was vary widely, the proportion of by friends, doctors, consulting services, advertising columns, and free publicity material were gradually increase, while the proportion of by television and radio gradually decline. The proportion of ever received HIV test was not high, but there was a rising trend with 16.2% in 2006, 29.8% in 2007,and 47.6%in 2008, the difference was significant (P<0.001).The proportion of ever received intervention service was increasing, there is a significant difference in each intervention item(P<0.001)Stratified analysis results showed that Different places, age, marital status, education level, ethnicity, AIDS knowledge score and whether ever received intervention services were have difference condom use rate. Unconsistent condom use with clients in the last month was independently associated with being<20 or≥25 years of age, lower education, being recruited from Non-venue based establishments, self-reported STD-related symptoms, and never received free condom. Unconsistent condom use with regular sex partners in the last month was independently associated with being≥25 years of age, being single, minority ethnicity, self-reported STD-related symptoms and never received STD examination and/or treatment.Of the participants,11.2% reported ever using illicit drugs with 2.8% ever injecting drugs. The proportion of ever using drug was 30.2% in Qingdao,2.0% in Yantai, and 0.0% in Dezhou, respectively. All drug using FSWs in Qingdao admitted taking methamphetamine, and some (4.5%) FSWs also smoked "Magu" and "K powder". Most of FSWs (85.7%) who had infected syphilis were coming from Qingdao survey site, so the data from Qingdao was analyzed separately, in order to understand the risk factors of drug using and syphilis infection.1211 eligible participants were investigated in Qingdao city in the three years, 41.9% were 20-24 years of age,85.1% were single,65.8% were Shandong residents, and 83.8% received middle school of education. Of 1211participants, nearly half had first lifetime sex at <18 years of age; 58.1% started sex work at <20 years of age; 60.2% only had <2 years of sex work experience, two-thirds had≥7 clients in the past week. Only 7.3% reported consistent condom use with regular sex partners and 42% with clients in the last month.30.2% reported using methamphetamine in the last 6 months with 1.6%(6) of the methamphetamine users ever injecting. Analysis results showed, methamphetamine users were more likely to be younger, single, recruited from Sauna/bath/KTV,<18 years of age at first lifetime sex,≥2 years of duration of commercial sex, have inconsistent condom use with clients in last month, and be syphilis-infected. Of 1211 participants,3% were syphilis-infected, with a dramatic increase from 1% in 2006 to 6.9% in 2008. The syphilis-infected participants were more likely to be ever having used methamphetamine, have inconsistent condom use with clients in last month, and have been tested for HIV.Female sex workers are at greater risk of experiencing harm from their club drug use, since clients often solicit FSWs in different venues to share drug and sex experiment. Hence, separate analyze was taken for the Qingdao data, in order to assess the impact of commercial sex venues on the syphilis and methamphetamine epidemics among FSWs. The results showed that The FSWs recruited from street-based entertainment were more likely to be older age and lower education level, while, FSWs recruited from night clubs or bars were more likely to be unmarried, higher education level and local residence. There were significant difference on the age of first commercial sex, the number of clients in the past week and drug behaviors, At the venue of saunas, night clubs or bars,61.1% started sex worker at <20 years of age, and the proportion were 49.2% at the venue of street-based entertainment and 50.4% at the venue of hair/beauty salons. Those FSWs recruited from street-based entertainment and hair/beauty salons had higher number of clients in the past week, the proportion of number of clients in the past week≥7 were 95.0% and 91.4%, respectively, while only 50.4% at the venue of saunas, night clubs or bars.33.0% FSWs recruited from saunas, night clubs or bars reported using methamphetamine, the proportion were 15.8% in street-based entertainment and 28.3% in. More than two third of FSWs recruited from street-based entertainment and hair/beauty salons may buy medicine from a pharmacy or don't cure if they felt uncomfortable. The FSWs recruited from street-based entertainment had lower proportion to receive intervention service than night clubs, had a lower proportion of ever received free condom, peer education and HIV-related materials, there was a significant difference.In the multivariate analysis, the street-based methamphetamine users were more likely to be single, not recruited from Shandong Province and have first lifetime sex <18 years of age. The night clubs/bars/sauna-based methamphetamine users were more likely to have their first lifetime sex<18 years of old, have had sex work≥2 years, younger age, had unprotected sex with clients in the last month and syphilis-infected. The hotels/hair/beauty salons-based methamphetamine users were more likely to be recruited from non-Shandong other provinces,<20 years of age and had unprotected sex with clients in the last month.In multivariate analysis, the night clubs/bars/sauna-based FSWs with syphilis infection were more likely to be methamphetamine users and have already attended HIV testing; the hotels/hair/beauty salons-based FSWs with syphilis infection were more likely to have had sex work≥2 years and syphilis infection.In multivariate analysis, the street-based FSWs who reported had unprotected commercial sex were more likely to have not received HIV testing and being single; The night clubs/bars/sauna-based FSWs who reported had unprotected commercial sex were more likely to have not received HIV testing, less education, had unprotected sex with clients in the last sex, be methamphetamine users and not sought any treatment for their STD symptoms; the hotels/hair/beauty salons-based FSWs who reported had unprotected commercial sex were more likely to be methamphetamine users and not sought any treatment for their STD symptoms. 2. The results of application of respondent driven sampling in the study among female sex workersIn total 363 participants, were recruited for the study. The longest recruitment tree had 25 recruitment waves, the evaluation variables including age, educational level, residence, income, and condom use with commercial sex partners in the last month have reached equilibrium. Of the total 363 participants, the youngest participant was 17 years and the oldest was 48 years old, the median age was 27 years. Most of the participants were unmarried,≥25-year-old age group, junior middle school education and coming from other provinces.The estimated population proportion has a low awareness of AIDS,59.2% of participants think mosquito bites can spread AIDS,41.8% do not think that timely treatment can help prevent AIDS, a high proportion of 50.4% think that washing the vagina after having sex or using some external use the mistake can prevent AIDS. Up to 58.8% of the participants think they will not or do not know whether infect AIDS infect, only 12.5% perceived themselves will have a high risk of HIV infection. More than one third of the FSWs do not know the symptoms of STDs among females and males.49.0% regularly use anti-inflammatory medicine in order to prevent sexually transmitted diseases.The age for the first sex experience ranged from 10 to 28 years old, the age for initiating commercial sex ranged from 16 to 45 years old.42.4% of participants have the duration of being a sex worker≥2 years.The proportions who had non-regular non-paying partners and regular partners was 31.1% and 75.2%. The condom use rate in the last sex with clients, non-regular not-paying partners and regular partner were 88.5%,46.3% and 43.6%, and the condom use rate in the last month were 60.8%,58.8% and 22.4% respectively.The estimated population proportions who had drinking history was 75.8% and 53.4% had smoking history.12.7% had history of ever using drug, among which only 8.7% had history of injection heroin drug use, while 91.3% of FSWs were taking new type drug including methamphetamine, K powder and ecstasy. Only 44.9% of FSWs had ever received condom distribution, STD examination and treatment, or AIDS counseling and other services in the last year, and 18.7% had ever taking HIV testing. None of the participants were HIV-positive, and the syphilis prevalence was 5.4%.Multivariate Logistic regression model showed that< 20 and≥25 years old groups, Shandong province residence, low establishment-based places and ever drug use were risk factors associated with unprotect commercial sex behaviors in the last month. Unmarried, Shandong province residence,<18 years old of the age for the first sex experience, and not continuous condom use with clients in the last month were risk factors associated with drug abuse.Conclusions1. High risk behavioral change research among FSWs in Shandong Province1.1 Female sex workers were the high risk population in the HIV/AIDS epidemic, their status of HIV infection and behaviors can reflect the epidemic in Shandong province. The results of this study showed that the HIV prevalence of FSws was still at a relatively low level in Shandong province.1.2 This study showed an increasing proportion on the AIDS awareness, condom use, and intervention services coverage from 2006 to 2008, which indicated the effectiveness of AIDS prevention and control in some extent. Nevertheless, there are many potential risks to spread the HIV epidemic in Shandong province, such as low condom use, multiple sex partners, drug use, and increasing STD prevalence.1.3 The FSWs who reported had unprotected commercial sex in the last month were associated with <20 and≥25 age groups, lower education level, recruited from street-based establishment, ever having STD-related symptoms and never received free condoms. Inconsistent condom use with regular partners in the last month was independently associated with≥25 years age, single, minority, ever having STD-related symptoms and never received STD examination and treatment.1.4 Up to 30.2% of female sex workers in Qingdao were methamphetamine users, univariate and multivariate analysis results showed that methamphetamine use was associated with unprotected sex behaviors and syphilis infection, which further illustrates "new type" drugs will be an important risk factor to HIV epidemic in Shandong province.1.5 Methamphetamine users among FSWs were more likely to be younger, single, recruited from Sauna/bath/KTV,<18 years of age at first lifetime sex,≥2 years of duration of commercial sex, have inconsistent condom use with clients in last month, and be syphilis-infected. The syphilis-infected participants were more likely to be ever having used methamphetamine, have inconsistent condom use with clients in last month, and have been tested for HIV.1.6 The factor of new type drug abuse has lead to higher unprotected sexual behaviors and STD infection among FSWs recruited from high-grade establishment, which was inconsistent with the traditional intervention strategies. Hence, more intervention efforts should put on the drug using FSWs recruited from the night club/bar/sauna places, at the same time, the FSWs recruited from street-based establishment shouldn't be ignored, the percentage of drug users increased from 5.0% in 2006 to 25.8% in 2008.1.7 There are many potential risks to spread the HIV epidemic in Shandong province, such as increasing STD prevalence and un-standard STD diagnosis and treatment, comprehensive intervention should be implemented to increase their HIV/STD awareness, protected behaviors and condom promotion, et al. Different interventions strategic should be implemented according to their different demographic characteristics and behaviors of FSWs.2. Application of respondent driven sampling in the study among female sex workers2.1 The application of respondent driven sampling to recruit FSWs is feasible, this method has its unique advantages, and still need be improved and developed to overcome some of the limitations.2.2 The HIV prevalence among female sex workers in Licheng District was low, but high risk sex behaviors among FSWs had been found. FSWs were the bridge population in the HIV/AIDS transmission. Its social networking features can be used to strengthen interventions.2.3 Female sex workers have low awareness of STD/AIDS. More flexible effective health promotion should be applied in Licheng District, while the peer education, STD diagnoses and treatment, and risk awareness education should be strengthened.2.4<20 years old and≥25 years old groups, local province residence, low establishment places and ever drug use were the risk factors associated with unprotected commercial sex in the last month. Unmarried, local province residence, <18 years of the age for first sex experience, and un-continuous condom use with client in last month were risk factors associated with drug use.2.5 The situation of "new type" drug abuse is not optimistic, effectively policies and measures to prevent and contain "new drugs" spread should be targeted for intervention efforts.Significance and Innovation1. In this study, three consecutive cross-sectional surveys with consistent recruiting procedures were conducted among FSWs across 3 cities from 2006 to 2008, serological and behavior surveillance were be applied in this study with a larger sample size, which can reflect the high-risk behavioral characteristics and its trends among FSWs in Shandong province.2. It was the first report the situation of new drug abuse and related factors in the country, the proportion of new drug abuse was 30.2% among FSWs in Qingdao city. The results showed that the association of new drug abuse, syphilis infection and unprotected sexual behaviors, further illustrated new drug abuse will be an important influent factor on HIV/STD epidemic in Shandong Province, which has important public health significance.3. The traditional intervention strategic had pay more attention on the street-based place, ignored the role of new drug abuse among FSWs at high grade establishments, which will provide scientific basis for making intervention strategy.4. This was the first application with RDS method to recruit FSWs in Shandong province, which will provide reference for future research in this population and other hidden populations.
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