Prevalence of sexually transmitted infections in female sex workers in Athens, Greece − 2005

ARTICLE

Auteur(s) : H Papadogeorgaki¹, C Caroni², E Frangouli¹, A Flemetakis¹, A Katsambas¹, M Hadjivassiliou¹

¹Microbiology, STD’s and AIDS Department, “A. Sygros” Hospital Athens, 5 Ionos Dragoumi str., Athens 161 21, GreeceFax: (+30) 210 3643282
²Department of Mathematics, National Technical University of Athens, Greece

accepté le 1 Juillet 2006

Materials and methods

Study population

According to data from the Ministry of Public Order, 700 female sex workers are holders of an official license for work and 10,000 are working illegally. Most of the illegal sex workers do not have access to medical services, mainly due to language or religion problems. Under the Greek law voted in January 2000, to obtain a working license as a sex worker it is compulsory to be examined for gonorrhoeae, Chlamydia trachomatis infection, early infectious syphilis and HIV infection in a public STD and HIV clinic. For the purposes of the present study, these women were also screened for HBV, HCV and HSV-2 infection.

All women were asked to answer anonymously a standard questionnaire with information on age, country of birth, country of permanent residence, education, STIs in the past, intravenous drug use at any time, use of condoms and duration of illegal sex working.

Laboratory methods

The COBAS Amplicor PCR test by Roche Molecular Systems, Branchburg, NJ, USA, was used for the identification of Chlamydia trachomatis on endocervical swabs.

A blood sample of 15 mL was drawn from each woman, centrifuged and the serum was stored in – 20 ^oC until tested.

Antibodies to Tr. pallidum were screened by using the VDRL slide flocculation test (DADE Boehring), the FTA-Abs (Trepo-Spot IF Bio Merieux), TPHA (Serodia – TR.PA by FUJIREBIO Inc.) and Tr. pallidum EIA IgG and IgM (BOYTY) Dark field microscopy test was not performed because none of the 299 women presented with an appropriate mucocutaneous lesion.

HIV infection was assessed by detecting antibodies to HIV-1 and HIV-2 by enzyme immunoassay (EIA) (Vironostika HIV Uni-Form II Ag/Ab by Organon-Teknika). Western Blot (New LAV Blot I by BIO-RAD) was not used since all blood samples proved negative by EIA.

The AXSYM EIA test by ABBOTT was used to determine HBsAg, HBcAg, anti-HBs, anti-HBc and anti-HBe for Hepatitis B and anti HCV for Hepatitis C. Since there is substantial evidence that Hepatitis C can be transmitted sexually as well as by injecting drug use, serological markers for it were also screened.

Type specific EIA (HerpeSelect Focus Diagnostics) was used to screen antibodies to Herpes Simplex Virus type 2 (HSV-2). Direct HSV-2 antigen detection tests were not performed since no woman presented with a genital ulcer.

During the same period of time 537,858 blood donors were screened by the blood banks all over Greece for syphilis, HIV, HBV and HCV. We used the blood donors as reference population and compared these data with ours although we are aware of the possible biases intervening in this comparison. In particular, the blood donors are drawn from all over the country and we do not have any information on their sex and age distribution. As reference group for HSV-2 we took 130 women who attended the same hospital with a clinical diagnosis of HSV-2 infection and also 53 asymptomatic Greek women with an age distribution similar to that of the sex workers.

Statistical methods

Results

The mean age was 39.7 years (standard deviation 10.5) in the total sample, 41.4 years (s.d. 10.4) among Greeks and 32.6 years (s.d. 7.8) among immigrants. The immigrants were thus younger than the Greeks on average (p < 0.001) and they were also better educated (x₃² = 21.5, p < 0.001, table 1( Table 1 )).

In the Greek sample, education was related to age (Kruskall-Wallis test, p < 0.001), with the better educated having a lower average age, but this was not the case among the immigrants (p = 0.68).

Neisseria gonorrhoeae was isolated from the endocervical swabs of 19 sex workers, 16 Greeks and 3 immigrants (1 Russian, 1 Georgian, and 1 Albanian). None of the pharyngeal or rectal swabs grew the microorganism. Sensitivity testing was done on Gonococcal agar base (OXOID) using the Kirby-Bauer method. No PPNG or TRNG strains were found among the isolates. The b-lactamase test was negative on all isolated strains (nitrocephin test by Glaxo). There was no difference in prevalence between the two groups of sex workers (x₁² = 0.199, p = 0.66).

The COBAS Amplicor test revealed Chlamydia trachomatis from 16 endocervical swabs – 12 from Greek sex workers and 4 from immigrants (3 Russian and 1 Albanian). Between the two examined groups of sex workers no difference in prevalence was found (x₁² = 0.296, p = 0.59). Coinfection with Neisseria gonorrhoeae was absent in our sample.

Herpes simplex type 2 infection was significantly more common in the Greek sex workers than in the immigrants (x₁² = 13.3, p < 0.001) but there was no difference in prevalence between the two groups for the other STI’s (p > 0.5) (table 2( Table 2 )).

For gonoccocal and chlamydial infection prevalence was related to younger age (p < 0.001), however, for syphilis (p < 0.001), Hepatitis B (p = 0.024) and HSV-2 infection (p < 0.001), prevalence was related to older age (table 3( Table 3 )). There did not seem to be such a relationship for Hepatitis C (p = 0.67), although the cases were few.

A statistically significant association was found between HSV-2 infection and syphilis: HSV-2 was present in 161/255 (65.7%) of sex workers negative for syphilis and in 47/54 (87.0%) of those positive for syphilis (x₁² = 8.52, p = 0.004). There were no other significant associations between pairs of STIs (p > 0.4).

In table 4( Table 4 ), the greatly increased prevalence of Hepatitis C and syphilis in the sex workers compared to blood donors is evident without the need for a statistical test. For Hepatitis B, there was a marginally significant relationship (x₁² = 3.81, p = 0.051) while for HIV infection the association was not statistically significant (p = 1.00).

The 74.6% prevalence of HSV-2 infection found in Greek sex workers was much higher than that recorded in asymptomatic Greek women of the general population (16/53, 30.2%, x₁² = 36.5, p < 0.0001) and in the sample of women with a clinical diagnosis of HSV-2 infection (38/130, 29.2%, x₁² = 69.7, p < 0.0001). No injecting drug use was confirmed. The use of condoms and the duration of illegal sex working were not evaluated since most of the answers were not satisfactory.
Table 1 Age and educational level of female sex workers

Discussion

The mean age of the Greek sex workers was quite high (41 years). This represents the fact that these women decide to register officially in an older age in an attempt to seek some form of “loyalty” in their profession but also the fact that some of them have to produce an official license since they are responsible for the running of the brothels.

Younger Greek sex workers tend to be better educated than older ones. This happens because a lot of young educated girls go into this profession due to the lack of jobs and their anxiety to acquire a “wealthy” standard of living.

The mean age of immigrant sex workers was 32.6 years. They are better educated than Greeks of the same age and this represents the difficulty these women face in finding an appropriate job when moving to a new country. This fact together with the small number of young immigrants who apply for an official license goes along with the Police and Immigration Office remark that young girls from Eastern Europe are quite often forced by networks of prostitution to migrate and go into illegal sex working.

The prevalence of Neisseria gonorrhoeae infection in our sample was 6.6%. This is greater than the prevalence of the infection in the general population of Greece (p < 0.001) [9] but it is closely related to older findings in STD clinic attendees in Athens, Greece [10]. Chlamydia trachomatis prevalence was 5.3% where prevalence in females in Greece is 3.5% (p = 0.08) [11] and in STD attendees 6.4% [10].

The prevalence rates for both infections are in agreement with most studies in female sex workers worldwide [12-14] and follow the trend for these two sexually transmitted infections in the literature – young age and multiple sexual partners, two factors consistently associated with the increased risk of the infection.

All the women in our sample were HIV negative. This is in agreement with the few similar studies in the literature [13, 14]. All other STIs investigated with the exception of Hepatitis C, which is not really sexually transmitted, showed an increased prevalence compared to the reference groups.

Extensive data with type specific serology on the seroprevalence of HSV-2 infection in the Greek population are lacking. Accurate type specific serological assays for HSV-2 infection identify persons with previously unrecognised HSV-2 infection [15, 16]. There is no specific policy for screening for HSV-2 in Greece, either in the general population or among high risk groups. The prevalence of the infection in Greek sex workers is high (74.6%) and this is in agreement with previous studies in the context of an STD clinic attendees in Athens, Greece [10]. It is higher than in immigrants (49.2%) but falls within the limits of the infection in STI patients [17, 18] and professional sex workers in other countries [19, 20].

Syphilis and genital herpes are the commonest mixed infections occurring together in 14.6% of the cases. This is common among sex workers [21] and represents the two most frequent causes of genital ulcer disease in Europe [22].

It is interesting that between the two investigated groups of sex workers the prevalence of any of the examined STIs is much higher in the Greek sample –75.8% versus 57.6% in the immigrant sample (table 2).

Female sex workers working legally in Greece are only a small percentage of those working illegally. From January 2000, when the prostitution law was voted, to today, according to official estimates from the Ministries of Internal Affairs, National Security and Health, approximately 10,000 women are working illegally as sex workers all over Greece. The majority of them are immigrants. Despite the small sample, the findings of our study clearly point out that the health system of Greece must find the way to intervene in the whole population of sex workers working legally or illegally in order to achieve better control of STIs.

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