Sexually Transmissible Infections in Clinical Practice

3. A Female Sex Industry Worker Requesting a Sexual Health Screen

Alexander McMillan1, 2  

(1)

Department of Genitourinary Medicine, NHS Lothian, Edinburgh Royal Infirmary, Edinburgh, Uk

(2)

University of Edinburgh, Edinburgh, Uk

Alexander McMillanFormerly, Consultant Physician, part-time Senior Lecturer

Email: a.amcmm@btinternet.com

Abstract

Two years later, Mary re-attends the clinic. She tells you that for the past 3 months she has been providing “escort services,” including sex. Although she is symptomless she requests testing for STIs. Her most recent sexual contact with a client had been about 10 days previously, and she had provided protected oral–genital and vaginal intercourse. Over the preceding 2 months she has had sexual contact with about five different clients per week, some men having been from South-East Asia. Clients use condoms consistently for vaginal sex but condoms are not always used for oral–genital sex. She has also been in a regular relationship for 18 months with a male partner who does not use condoms for intercourse. She does not use recreational drugs, but she does not know if any of her clients have ever injected such drugs. The Implanon ® had been replaced about 1 year previously. Her general health remains good and she is not receiving any other medication. She has had no further pregnancies.

Two years later, Mary re-attends the clinic. She tells you that for the past 3 months she has been providing “escort services,” including sex. Although she is symptomless she requests testing for STIs. Her most recent sexual contact with a client had been about 10 days previously, and she had provided protected oral–genital and vaginal intercourse. Over the preceding 2 months she has had sexual contact with about five different clients per week, some men having been from South-East Asia. Clients use condoms consistently for vaginal sex but condoms are not always used for oral–genital sex. She has also been in a regular relationship for 18 months with a male partner who does not use condoms for intercourse. She does not use recreational drugs, but she does not know if any of her clients have ever injected such drugs. The Implanon ® had been replaced about 1 year previously. Her general health remains good and she is not receiving any other medication. She has had no further pregnancies.

3.1 What Tests Would You Undertake Now, and Against Which Infection Might You Consider Vaccinating Her?

The tests that were performed at her initial clinic attendance should be undertaken. In addition:

·               Take a pharyngeal specimen for culture or examination by a NAAT1 for N. gonorrhoeae. A cotton wool-tipped applicator stick is passed over the pharynx and both tonsils or tonsillar beds, and either plated directly on to selective culture medium or sent to the laboratory in the appropriate transport medium. The majority of individuals with pharyngeal infection are symptomless, but, untreated, there is the possibility of transmission to a sexual partner, and the woman is at risk for disseminated infection (see Case 24). Some studies have shown that, among female sex industry workers, the incidence of pharyngeal gonorrhoea is higher than that of genital tract infection. This may be explained by consistent condom use for vaginal or anal intercourse but not for oral–genital sex.

·               Test for rectal gonorrhoea as follows, depending on local clinic and laboratory practices:

·                                   Obtain material for culture for N. gonorrhoeae by gently inserting a cotton wool-tipped applicator stick into the anal canal to a distance of about 2–3 cm, withdrawing, and inoculating a plate of selective culture medium. Or,

·                                   Obtain material as above and send to the laboratory in appropriate transport medium for culture. Or,

·                                   if a nucleic acid amplification test (NAAT)1 is used for the detection of N. gonorrhoeae, obtain rectal material using the swab provided by the manufacturers of the test kit, break it into the buffer solution, and send it to the laboratory.

Note:

The detection rate of gonococcal infection is identical whether a specimen is obtained blindly or through an anoscope.

The majority of infected women (up to 75% of cases) are symptomless, the remainder having features of a distal proctitis (see Case 20). If she remains untreated, in addition to transmission of infection to a partner, the woman is at risk of complications such as perianal abscess formation and disseminated infection, and she is at increased risk for HIV infection.

·               Obtain a specimen of anorectal material for testing for C. trachomatis by a NAAT. The swab provided by the manufacturers of the test kit is inserted about 2.5 cm into the anal canal, withdrawn, and the specimen sent in the solution provided to the laboratory. Although these assays are not yet licensed for use on rectal specimens, they are widely used in clinical practice. Most women rectally infected with the common, oculogenital genotypes of C. trachomatis are symptomless.

·               A serum sample should be tested for hepatitis B surface antigen and core antibody, and if these tests are negative she should be offered vaccination. Several studies have shown that female sex industry workers are at increased risk for this infection. Many health-care providers administer the first dose of vaccine before the results of serological tests are available. Although there is no clear evidence that female sex industry workers are at increased risk of hepatitis A, many physicians vaccinate these women against both hepatitis A and B.

·               Serological testing for hepatitis C virus (HCV) infection should be offered. Some, but by no means all, studies have shown an increased prevalence of HCV infection among non-drug-injecting female sex industry workers.

One week later Mary is given the results of the most recent tests: there is no evidence of an STI. She is encouraged to use condoms consistently for penetrative sex with her clients, and she is also encouraged to attend the clinic regularly for screening for STIs. As she has no serological evidence of prior infection with hepatitis B (both hepatitis B surface antigen [HBsAg] and anti-core antibody [anti-HBc] assays were negative), she is offered and accepts vaccination against this infection. Table 3.1 indicates the most commonly used vaccination schedules.

Table 3.1.

Vaccination schedules for hepatitis B.

Engerix B® (20 μg/mL) 1 mL by intramuscular

injection given at 0, 7, and 21 days, with a booster at 12 months

OR *

Engerix B® or HBvaxPRO ® (40 μg/mL) 1 mL by intramuscular

injection at 0, 1, month and 6 months

OR

Engerix B®1 mL by intramuscular injection at 0, 2 weeks,

6 weeks, and 12 months

OR

(if Hepatitis A vaccination also indicated)

Twinrix® 1 mL by intramuscular injection at 0, 7, and 21 days,

with a booster at 12 months

OR

Twinrix® 1 mL by intramuscular injection at 0, 1 month, and 6 months

OR

Twinrix® 1 mL by intramuscular injection at 0, 2, 6 weeks, and 12 months.

Although more than 95% of healthy vaccinees develop protective antibody, it is good practice to test for a satisfactory immune response about 2 months after the final dose of vaccine. Serological testing ofMary at that time showed a concentration of antibody against hepatitis B surface antigen (anti-HBs) of 310 mIU/mL. What information would you give her?

Mary has had a good immune response to hepatitis B vaccination. Available data suggest that immunity is likely to be lifelong and that further doses of vaccine are unnecessary. Individuals with sub-optimal levels of anti-HBs should be managed as outlined in Table 3.2.

Table 3.2.

Interpretation of tests for hepatitis B surface antibody (anti-HBs) after completion of a course of vaccine.

Level of anti-HBs

Action

>100 mIU/mL

No further boosters or serological tests for hepatitis B markers required

10–100 mIU/mL

Give a further dose of vaccine and repeat test for anti-HBs 4–6 weeks later (if still poor response consider no further action)

<10 mIU/mL

Give a further dose of vaccine 6 months after the last dose and repeat anti-HBs test 4–6 weeks later. If still partial response, give a further booster and retest 4–6 weeks later. If the level of anti-HBs is still non-protective, do not give further vaccine but advise patient that he/she is susceptible to infectiona.

aNon-responders should be informed that they can receive hepatitis B immunoglobulin (HBIG) if they have a (definite) hepatitis exposure in the future.

Footnotes

1

Although they are not yet licensed for use on pharyngeal and anorectal specimens, NAATs, particularly single-strand displacements assays (SDA) appear to be more sensitive than culture for the diagnosis of gonorrhoea at these anatomical sites. A positive result in a nucleic acid amplification assay should preferably be confirmed by culture or an alternative NAAT.