Medication Use by Female Sex Workers for Treatment and Prevention of Sexually Transmitted Diseases, Chiang Rai, Thailand


Original Article

Background:: Female sex workers (FSWs) in Thailand are at high risk for sexually transmitted diseases (STDs). Although regular attendance at public STD clinics is required, FSWs may frequently use medications obtained in the community for STDs.

Objectives:: To determine the frequency of use of medications for STDs from sources other than public STD clinics among FSWs in Thailand and to describe factors associated with such medication use.

Methods:: A cross‐sectional survey of FSWs attending the public STD clinic in Chiang Rai, Thailand, was performed.

Results:: Of the 200 FSWs interviewed, 55% had ever used medications to treat or prevent STDs from a source other than a public STD Clinic, and 36% had done so in the prior year. Most use (79%) was to treat STD symptoms, and medication was most frequently obtained directly from a pharmacy (54%). This use of community medication for STDs was associated with younger age, non‐Thai ethnicity, seeking STD treatment during the current clinic visit, and brothel‐based sex work.

Conclusions:: Use of medications from various sources in the community was common among these FSWs. Further research is needed to determine the appropriateness of this treatment. Innovative methods to ensure adequate quality STD care by community providers and to improve the health‐care‐seeking behaviors of these high‐risk women are needed.

*From the Division of STD Prevention, National Center for HIV, STD and TB Prevention, Centers for Disease Control and Prevention, †Epidemic Intelligence Service, Epidemiology Program Office, Centers for Disease Control and Prevention, ‡Division of HIV/AIDS Prevention, National Center for HIV, STD and TB Prevention, Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, Atlanta, GA; §The HIV/AIDS Collaboration, Nonthaburi, Thailand, ∥Chiang Rai Provincial Health Office, Chiang Rai, Thailand

The authors thank Jitkasem Thongpun and Chaowanart Chatpichit for performing the study interviews and Dr. Brian Edlin for his helpful suggestions on the manuscript.

Reprint requests: Peter Kilmarx, MD, The HIV/AIDS Collaboration, DMS 6 Building, Ministry of Public Health, Tivanon Road, Nonthaburi 11000 Thailand.

Received for publication May 22, 1997, revised August 19, 1997, and accepted August 22, 1997.

Article Outline

The use of appropriate antimicrobials cures symptoms of sexually transmitted diseases(STDs), prevents their transmission, and prevents sequelae including infertility, adverse outcomes of pregnancy, and facilitation of human immunodeficiency virus (HIV) transmission. Conversely, inappropriate antimicrobials do not cure or prevent STD transmission or sequelae, and their use could delay receiving appropriate care. Use of inappropriate antimicrobials could also lead to the selection of resistant STD pathogens.

Unfortunately, antimicrobials are often not prescribed by trained practitioners with adequate clinical skills and laboratory support. Particularly in resource‐poor settings, antimicrobials for STDs are often obtained directly from a pharmacy, friends, or other sources in the community away from an STD clinic or other setting where trained practitioners treat STDs appropriately.1–3 Such informal antimicrobial use may be more likely to be inappropriate than treatment from an STD clinic. STD treatment in the community may not be accompanied by risk‐reduction counseling or provision of condoms.2 Also, these STDs are not reported to public health authorities, so contact tracing and treatment are not possible. Because public clinics serve as the principal source of STD surveillance data in many settings, population STD incidence in surveillance reports is underestimated.4 On the other hand, easy access to antimicrobials may be advantageous where access to medical care is otherwise limited. Where it is widespread, use of antimicrobials obtained in the community could be an important factor in STD control.

Female commercial sex workers are at high risk for STDs and their sequelae and may transmit STDs to their commercial and noncommercial sex partners. Other studies have shown that FSWs frequently use antimicrobials obtained in the community for STDs.5 To determine the frequency of community medication use for STD treatment or prevention, describe risk factors for community medication use for STDs, and determine whether community medication use for STDs is associated with HIV infection among FSWs, we performed a cross‐sectional study of FSWs in Chiang Rai, Thailand.

Since the late 1980s, Thailand has experienced an explosive epidemic of HIV, largely because of male patronage of FSWs,6,7 with the highest rates in upper northern Thailand.8 High rates of STDs among FSWs and their sex partners have been proposed as an important contributing factor of the HIV epidemic in Thailand.6,7 Reported rates of STDs in Thailand have declined since a campaign promoting the use of condoms for commercial sex was initiated in 1989,4,9,10 and HIV prevalence among male military recruits has also declined in the 1990s.11 Chiang Rai (1995 population 1,200,000) is Thailand's northernmost province bordering Laos and Myanmar (Burma) in an area known as the Golden Triangle. In Chiang Rai province, reported STDs declined from a total of 3,130 cases in 1989 to 711 cases in 1994.12 In the city of Chiang Rai (population 39,000), there were estimated to be 407 FSWs working in 46 commercial sex establishments in 1995, of whom 25% were HIV infected (Chiang Rai Provincial Health Office). Brothel‐based FSWs, who have more commercial sex partners, were twice as likely to be HIV infected as non‐brothel‐based FSWs working in venues such as karaoke bars or massage parlors.

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The survey was performed in the single public STD clinic in the city of Chiang Rai, Thailand, from May to August 1995. All FSWs visiting the clinic during the this time who could speak Thai were asked to be interviewed. Interviews were performed by registered nurses fluent in the northern Thai dialect using a standardized questionnaire. Information about ethnicity was self‐reported. In general, Tai Yai FSWs in Chiang Rai have families in the Shan state of Myanmar and have come to Thailand to practice commercial sex. Hill tribe FSWs are from any of several non‐Thai ethnic groups in Thailand, including Akha, Karen, Lisu, and Yao. Data on antimicrobial treatment at prior clinic visits were abstracted from the clinic medical record. To assess recall of previous use of medication, we compared recall of having received medication from the STD clinic with STD clinic records.

The HIV/AIDS Collaboration and Chiang Rai Provincial Health Office were conducting a cohort study of FSWs in Chiang Rai in the same time period.13 Eighty‐seven women participating in the antimicrobial use interview survey were also enrolled in the cohort study. Data from the cohort study were linked to the results from the survey for these women. Cohort study members were being reimbursed for transportation expenses for each scheduled STD clinic visit and were receiving the first 100 baht ($4.00) of medication free at each visit. At cohort study enrollment, women were interviewed about sociodemographic and behavioral risk‐factor information; endocervical swabs were collected and tested for presence of Chlamydia trachomatis and Neisseria gonorrhoeae using a nucleic acid hybridization test (GEN‐PROBE PACE 2 System, [San Diego, CA]); and serum specimens were collected and tested for reactivity to the Treponema pallidum hemagglutination assay (TPHA). At enrollment and every 3 months (until seropositive), serum specimens were collected and tested for antibodies to HIV using an enzyme immunoassay and Western blot.

Data were double entered using Epi‐Info, version 5.01b (CDC, Atlanta, GA), and SAS, version 6.11 (SAS Institute Inc., Cary, NC), was used for analysis. Odds ratios and a multiple logistic regression model were used to analyze associations between community medication use for STDs in the previous year and sociodemographic factors among all study subjects. To analyze the association between HIV‐infection status and lifetime community medication use for STDs among cohort study members, a backward elimination logistic regression model was used controlling for cohort study enrollment STD test results and sociodemographic and behavioral factors. These factors were enrollment gonococcal‐, chlamydial‐, and TPHA‐test status; age; brothel‐ (vs. non‐brothel‐) based sex work; average number of customers per night working; condom use; vaginal sex during menses; duration of sex work; age of initiation of sex work; customer charge; and number of working days in the last 3 months. A threshold of P > 0.25 was used for elimination of factors from the model, except lifetime community medication use for STDs, which was forced to remain in the model.

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Two‐hundred FSWs were interviewed. Most of the interviewees were more than 20 years of age, were from the Thai ethnic group, and had initiated commercial sex work more than 2 years before being interviewed (Table 1). Only 6% of the women were seeking STD treatment during the STD clinic visit when they were interviewed. Other women were making routine STD clinic visits, such as for regular STD checkups that were mandated for FSWs by health officials.

There was good agreement between recall of having received medication from the study STD clinic and the STD clinic records. Of 83 who reported that they had ever previously received medication from the STD clinic, 72 (87%) had this documented in the clinic record. Conversely, of 108 who did not recall ever having previously received medication from the clinic, 92 (85%) had no prior medication documented in the clinic record (overall concordance 86%).

More than half (55%) of the interviewees reported having ever taken any medications by mouth or injection that they did not get from an official government STD clinic to treat or prevent sexually transmitted infections, including 6% who had done so in the prior 2 weeks, another 5% between 2 weeks and 1 month previously, and 24% 1 month to 1 year previously‐a total of 36% in the previous year (Figure 1). Frequency of such use of medication from the community for STDs was similar to frequency of receiving antimicrobials from the study STD clinic (34% in the previous year), and 59% had received medication from either source in the previous year. In the most recent episode, most women had used the medications from the community to treat STD symptoms (79%), although routine, STD‐preventive use was also reported by 18% (Table 2).

Of these 110 women who had used medication from the community for STD, in the most recent episode 85 (77%) had used a single medication, 20 (18%) had used 2 medications, 4 (4%) had used 3, and 1 (1%) had used 4 medications. Of these 141 medications, 123 (87%) were administered orally, and 18 (13%) had been given parenterally. In most cases, the women did not know what the medication was (123 [87%] of the 141 medications). Women did report having received chloramphenicol (7 cases), kanamycin (5), rifampin (4), tetracycline(1), and thiamphenicol (1). Of the 123 unknown medications, women reported that they believed that 85 (69%) were antimicrobials and that 11 (9%) were not antimicrobials, and they did not know whether the medications were antimicrobials in 29 cases (23%).

Most frequently, these medications had been obtained directly from a pharmacy (60 [54%] of the 110 women's most recent episodes) or from a private doctor or clinic (33 [30%]). The other reported sources were the hospital (7 [6%]), a health care worker at their commercial sex work establishment (3 [3%]), a grocery store (3[3%]), an owner or manager at their commercial sex work establishment (2[2%]), or friend or coworker (2 [2%]).

Use of medication from the community for STDs in the prior year was associated with younger age, non‐Thai ethnicity, seeking STD treatment during the current clinic visit, and brothel‐based sex work (Table 3). These associations remained statistically significant when controlled for all of the other factors shown in Table 4. There was also more use among women who had started sex work 2 to 5 years before the interview.

For 87 women who were enrolled in the HIV/AIDS Collaboration FSW cohort study, other data including STD and HIV test results were available. Among these 87 women, 22 (25%) were HIV‐infected, and at cohort study enrollment, 6 (7%) had gonorrhea, 13 (15%) had chlamydial infection, and 28 (32%) had positive TPHA tests. In the prior year, 28 (32%) had used medication from the community for STDs and 60 (69%) had received antimicrobials from the study STD clinic. The 49 women(56%) who had ever used medications from the community for STDs were somewhat more likely than women who had never done so to be HIV infected (crude odds ratio 2.6[95% confidence interval, 0.9 to 7.4]). In the multiple regression model, lifetime use of medication for STDs obtained from a source other than a government STD clinic was not significantly associated with HIV infection (odds ratio 1.3 [95% confidence interval 0.3 to 5.7]). Five other factors remained in the model and were associated with HIV infection: (1) positive gonococcal test or (2) positive TPHA test at cohort study enrollment, (3) younger age, (4) vaginal sex during menses, and (5) lower customer charge.

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In this study we interviewed 200 FSWs in a public STD clinic in northern Thailand and found that most (55%) had used medication for STDs obtained from sources in the community other than a public STD clinic. Most of this use (79%) was directed at STD symptoms, and in most cases(54%) the medication was obtained from a pharmacy. This use of medication from the community for STDs was associated with other factors that put sex workers at higher risk for STDs, including younger age and brothel‐based sex work.

Studies of other populations have also found high rates of use of medication from the community for STDs. In the Philippines, 31% of FSWs who had had sex with customers in the previous 2 weeks reported that during that time they had used antimicrobials as a prophylaxis against STDs.5 Among male military conscripts in northern Thailand with a history of STDs, 65% had ever self‐treated with antimicrobials for STDs3; and a third of male clients of FSWs in Indonesia reported prior self‐treatment with antimicrobials for STDs.2 In Kenya, 23% of men and women with STDs had sought treatment from practitioners in the informal sector, including pharmacists and traditional healers, before coming to the study STD clinic.1 In the United States, 8% of men and women had taken antimicrobials in the 14 days before coming to an STD clinic, and in only 18% of these cases had the antimicrobial been prescribed by a health care provider for the current infection.14

In this study, most FSWs did not know what medications they had received, but treatment failure of both gonorrhea and chlamydia would be common with the agents mentioned.15 In the prior year, 59% of interviewees had received medication from either the STD clinic or the community. This high rate of use could exert considerable pressure for the selection of drug‐resistant STD pathogens and other pathogens in this population.

There are several other implications of this high rate of use of medication from the community for STDs. Symptoms are a notoriously poor indicator of sexually transmitted infection among women,16 and much of this treatment, and treatment side effects, may be unnecessary. If these treatments are not curative for infected women, STD sequelae and transmission are not prevented. Treatment of sex partners and risk‐reduction counseling may not be incorporated with treatment outside an STD clinic, and reinfection may be more likely. Future research should assess the efficacy of community‐acquired medication for STDs and whether partner treatment, counseling, and provision of condoms are practiced by community providers. Effective programs to reach out to and improve the practices of providers outside of public STD clinics must be developed and implemented. Initial efforts have included the training of pharmacists in STD management in Nepal17 and the development of a kit with standardized, prepackaged therapy in Cameroon.18

Since self‐treated STDs are generally not reported to public health authorities, STD incidence may be greatly underestimated in surveillance reports. In this study, use of medication from the community for STDs was prevalent even among FSWs concurrently enrolled in a cohort study with regularly scheduled STD clinic visits and for whom STD clinic treatment was subsidized. In epidemiologic research studies, to the extent that STDs are treated in the community and not detected, STD incidence is underestimated. This misclassification of STD status causes risk factor estimates to be biased toward the null hypotheses. For example, an association between STDs and HIV infection may not be detected if STDs are under diagnosed. Research studies should therefore attempt to minimize undocumented treatment and undiagnosed infection.

Among FSWs who were also in the cohort study (for whom HIV‐infection status was known), women who had ever used medications from the community for STDs were somewhat more likely to be HIV‐infected than women who had not, although this was not statistically significant, especially when controlled for other risk factors. This contrasts with a cross‐sectional study from northern Thailand in which men who had self‐treated for STDs were less likely to be HIV infected than men with a history of STDs who had not self‐treated.3 Prompt self‐treatment of STDs with effective antimicrobials could certainly be protective against HIV infection, particularly as compared with no treatment at all. However, in general, self‐treatment of STDs cannot be recommended because of the potential for misdiagnosis, inappropriate treatment, adverse drug side effects, and emergence of antimicrobial resistance.19

There were several limitations to this study. Women recruited in this STD‐clinic‐based convenience sample may differ in health‐care‐seeking behavior and medication use from FSWs recruited at their workplaces. Most women were not able to identify what medication they had used, which limits any conclusions about efficacy of treatment. The small number of cohort study members limits the power of the analysis of the association between HIV infection and use of medication from the community for STDs.

Better understanding of health‐care and risk behaviors of people with STDs is needed. Some men and women at high risk for STDs use prophylactic antimicrobials and, because of a false sense of security, do not use condoms.5,20,21 In this study, the FSWs who were younger and non‐Thai and who engaged in brothel‐based sex work were more likely to have used medication for STDs obtained from a source other than a public STD clinic. Innovative methods are needed to improve the health behaviors and to address the health needs of these women, who are also likely to be marginalized in society and are at high risk for STDs and HIV infection.

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