SEXUALLY TRANSMITTED INFECTIONS (STIs), like chlamydia and gonorrhea are serious health concerns that threaten the general health, well-being and reproductive capacity of many Canadians. In Canada, chlamydia is the most commonly reported bacterial STI and between 1997 to 2001, rates of chlamydia have increased by 70% (from 113.9–197.1 per 100,000 nationally).1
After chlamydia, gonorrhea is the second most commonly reported bacterial STI1 and if untreated, both chlamydia and gonorrhea may result in serious health consequences especially for women; these include: pelvic inflammatory disease (PID), chronic pelvic pain, tubal infertility and ectopic pregnancies among others.2 High rates of chlamydia, gonorrhea and other STIs are commonly found among certain Canadian Aboriginal populations (i.e., First Nations and Inuit) and in some regions (e.g., Nunavut and North West Territories), rates have been reported to be more than 10 times the national average.1 Over the past decade reported rates of chlamydia infections have risen dramatically (51–278 cases/100,000 persons)3 making it the most prevalent STI in North America and Europe. Despite this known increase, screening of chlamydia and other STIs remains inadequate, especially among Aboriginal populations.
In Canada, STI screening has traditionally been based on a “selective screening process” whereby, distinct populations are targeted and screened (e.g., prenatal women, named contacts and symptomatic individuals). Selective screening however, does not capture all infected and/or at risk individuals such as males and adolescents (especially because of the asymptomatic nature of certain STIs) and subsequently, has a limited effect on decreasing transmission.4,5 This situation is problematic especially, for remote populations that often have inadequate access to health care services, live in communities with greater than 10% STI prevalence, have cohesive sexual networks and, at risk for STI related complications.1
Implementing a universal screening program with prompt treatment and contact tracing is one method that can be used to control disease spread in remote Aboriginal communities. Because universal screening programs target all individuals, they would allow for the detection and treatment of asymptomatic cases which in turn, would limit the transmission of infections within sexual networks.6 Universal screening of STIs has been shown to be efficacious in controlling disease spread in populations with greater than 10% disease prevalence and in “closed” populations were the risk of having an infected partner are high.7,8 To the best of our knowledge there have been no published studies examining the use of universal screening among asymptomatic individuals in the Baffin Region. The two main objectives of this study were to determine a more accurate count of chlamydia and gonorrhea infections in a Baffin Inuit community and determine the efficacy of universal screening, prompt treatment and contact tracing in decreasing disease burden.
Materials and Methods
Study Community
The community was located in the Baffin region (Nunavut, Canada) and was selected on the basis of logistical feasibility and support from the community council and community members. The community was representative of other communities in the Baffin region about age/sex distribution (Tables 1 and 2), demographics, isolation, access to health care services, and rates of STIs.
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TABLE 1: Demographic Characteristics of the Study Population
TABLE 2: Demographic Characteristics of the Baffin Region (Ages 15–64 in 2001)
Sample Selection
Sample selection for the cross-sectional group (i.e., target population) was open to all Inuit males and females between the ages of 15 and 65 that resided in the study community during the study period (this excluded all individuals that were away hunting, working on fishing vessels, visiting other communities or staying at out-post camps). Study participants were approached and recruited at the community health centre, local high school and community centre by the investigator, health centre staff, community health representative (CHR) and by word of mouth. Announcements were also made on the local radio station and through the use of flyers. Participants were paid a small honorarium for their time. For the longitudinal cohort a random sample of participants from the cross-sectional study group was selected and followed every two months post baseline visit for an additional four visits.
Cross-Sectional Survey (Baseline Visit)
The cross-sectional survey was used to determine a more accurate count of chlamydia and gonorrhea prevalence among the study population. All participants captured in the cross-sectional survey were interviewed and screened for chlamydia and gonorrhea (between August 1st to September 1st, 2003) with a urine based, Nucleic Acid Amplification test.
A questionnaire in either English or Inuktitut was used to collect information on demographics, use of health services, sexual histories, knowledge of STIs and contraceptives, and number of sexual partners among others. Chart reviews were also completed for all the participants to obtain more detailed information on use of health services, previous STIs and health histories.
All urine specimens were collected and packaged at the Health Centre by the principle investigator. Samples were flown to Baffin Regional Hospital (Iqaluit, Nunavut) on a weekly basis. All positive and/or symptomatic individuals and their partners were promptly treated according to regional policies (i.e., witnessed dose of 1 g of Azithromycin for chlamydia and 400 mg of Cefixime for gonorrhea) and contact tracing was completed. In addition, all participants received the usual health teaching on the prevention of STIs and were offered condoms.
Longitudinal Cohort (Follow-up Visits)
The purpose of the longitudinal cohort was to determine the effect of the baseline screening, treatment and contact tracing intervention on decreasing chlamydia and gonorrhea prevalence and incidence among the study group. We assumed that the majority of the individuals in the longitudinal cohort had sexual partners that were only screened at baseline or, were not screened at all (e.g., from other communities). Participants from the cross-sectional group were randomly selected to be followed every two months postbaseline visit for an additional four visits (October 2003 to May 2004). During each visit, participants were interviewed about their sexual partners and were screened with a urine based nucleic acid amplification test. Similarly, all positive and/or symptomatic individuals and their partners were promptly treated with the same treatment protocol as the baseline visit and contact tracing was completed.
Data Analysis
All data were collected, coded and analyzed by the principle investigator with the use of SPSS and S-PLUS version 6.2. Exploratory analysis was completed on all the variables and the Odds Ratios with 95% confidence intervals were computed with a forward stepped Logistic regression analysis where the outcome variable was a positive STI test result and the explanatory variables included: sex, age, number of previous STIs, age of sexual debut and last STI result pre study. The goal of the Logistic regression model was to help explain factors that may predispose individuals to acquiring and transmitting an STI. To determine the effectiveness of the baseline intervention (i.e., universal screening followed by prompt treatment and contact tracing), the McNemar’s test of correlated proportions was used to analyze the “before and after” effect of the baseline intervention in preventing chlamydia and gonorrhea incidence among the cohort of participants during each of the follow-up visits.
This study was approved by the University of British Columbia clinical ethics review board and a research license was issued by the Nunavut Research Institute. All participants provided written informed consent.
Results
One hundred and eighty-one participants (i.e., from a target population of approximately 224 people) (Nookiguak, personal communication, 2003) in the cross-sectional survey were screened and interviewed (Table 1). This yielded, 21 cases of chlamydia (6 males, 15 females), 0 cases of gonorrhea; the response rate was 100% (based on the sample population). Every, participant that tested positive for chlamydia (i.e., all 21 cases) was treated with a witnessed dose of Azithromycin (1 g); as for the partners, all sexual contacts that were listed by the participants and subsequently, resided in the study community were also treated with a witnessed dose of Azithromycin. For the partners that resided in other communities, their treatment was carried out by the community health nurses from those respective communities.
When analyzing the association between males and females and having a positive chlamydia, the Chi-square test result was not significant (P = 0.26). The mean age of individuals who had a positive chlamydia result was 22.1 (SD: 6.3) compared with 30.6 (SD: 9.9) for those not infected and this difference was however, significant (P <0.01). Based on the baseline data (i.e., regression analysis) the strongest predictor for acquiring a chlamydia infection during the study period was having a recent diagnosis (i.e., within the last 3 months) of chlamydia or gonorrhea before the study (OR = 9.82, CI: 2.70, 35.77). Other risk factors, though not statistically significant included: female gender (OR = 2.45, CI: 0.55, 10.89) and a history of greater than 2 previous STIs (e.g., chlamydia, gonorrhea, herpes, syphilis) (OR = 1. 47, 0.92, 2.30). The 3 major barriers to condom use reported by the participants included: offending their partners (58%); fear of suggesting that the individual has an STI (64%) and difficult to plan ahead for (43%).
In the longitudinal cohort, 100 participants were randomly selected from the cross-sectional group of which, 99 participants were followed until completion. One participant was lost to follow-up as a result of suicide after the first follow-up visit. In the combined follow-up visits, 14 new cases of chlamydia were detected (3 males, 11 females); 13 individuals had a positive chlamydia result during their baseline visit and subsequent reinfections during the follow-up visits. As indicated in (Table 3), the McNemar’s test yielded significant values for the Baseline intervention during visits 1, 2 and 4 yielding fewer new chlamydia infections. During visit 3 however, the intervention was not significant as the infections were among participants that did not have a prior infection during the baseline visit.
TABLE 3: McNemar Test Results for the Baseline Visit Intervention During Each Visit
In addition, the Chi-square test for association between sex and having a positive chlamydia in the follow-up visits was not significant (P = 0.54). The overall mean age of individuals who had a positive follow-up chlamydia result was M = 22.4 whereas, for individuals not infected, the mean age was M = 28.7. The difference between the positive and negative participants was significant (P = 0.008).
Discussion
Overall, 35 cases of chlamydia were detected during the complete study period (August 1st, 2003 to June 30th, 2004) with 21 detected during the baseline visit and 14 during the follow-up visits. The prevalence of chlamydia during the baseline visit was 11.6% (i.e., 21cases of chlamydia in the study population of 118) in comparison to the 2.7% that was reported for 2000 (Saxton, personal communication, 2003). The prevalence rate however, must be interpreted with discretion as the population size was small and variable because of the transient nature of the population and because of seasonal factors (e.g., employment, camping, hunting). Furthermore, the prevalence rate calculated in 2000 was likely based on a slightly larger population size and as such, may have lowered the prevalence rate.
Keeping these factors in mind, the number of chlamydia cases detected during the study period (2003–2004) were higher than the number of cases reported per year, during the years 1991–2000 where the average number of cases recorded was 14 (Saxton, personal communication, 2003). This finding supports our hypothesis that the current screening practice may have undercounted the prevalence of chlamydia (Fig. 1). Although our findings were restricted to the Study Community, we believe that similar findings would have been seen in other communities within the Baffin region, should a comparable screening and intervention program been implemented.
Fig. 1: Reported Chlamydia cases in the test community (1991–2004). *Urine PCR for chlamydia and gonorrhea screening was introduced in the Baffin region (Saxton, 2003: personal communication).
With regard to gonorrhea, no cases were detected. This finding can be accounted for by the general decrease in gonorrhea prevalence in the Baffin region and was consistent with the results of a study that was conducted in the Baffin Region around the same time (Saxton, personal communication, 2003). The investigators found that gonorrhea prevalence dropped to 1.0% in the Baffin region and to 1.7% in the Kivalliq region.
Another important note is that before 1996, chlamydia and gonorrhea screening was done through culture swabs; an invasive procedure that requires a swab to be inserted into the urethra for males and vagina for females. In comparison to culture swabs, urine PCR has an overall sensitivity of about 93.1% for chlamydia and 90% for gonorrhea and a specificity of about 97% for both chlamydia and gonorrhea.9 More important however, urine screening is often, a more acceptable method of screening for males and for asymptomatic individuals.
For the longitudinal study, we wanted to determine the impact the baseline intervention had on the prevention of new cases during the four additional visits. We hypothesized that the baseline intervention would be effective in preventing new cases of chlamydia and or gonorrhea infections in all four visits assuming that the majority of individuals in the cohort had partners that were screened during the baseline visit. We found however, that the intervention was not effective in reducing new cases of chlamydia in the third visit (6 months post baseline; P = 0.05). These findings may have resulted from participants having partners in different communities or, from a partner that was not captured in the baseline/follow-up screening.
From our regression analysis, a strong predictor for testing positive for chlamydia was being female however, the Chi-square analysis for association between sex and having a positive chlamydia result was not significant. In the Baffin region, women are generally more screened for chlamydia and gonorrhea than men (e.g., prenatal and well woman visits) and physiologically more susceptible to infection especially, for the adolescent population (i.e., because of their immature cervixes). This may account for the fact that more positive infections (especially asymptomatic ones) were found among females. Furthermore, females may also be reinfected by their unscreened, positive male partners. The other strong predictor was having a previous STI (e.g., chlamydia, gonorrhea, herpes, syphilis) and this risk factor is commonly sited in the literature.10,11
There were two main limitations of this study: small sample size and recall. Based on the Study Community registry (Nookiguak, personal communication, 2003) there were approximately 224 people that met the age and ethnicity criteria. This number however, does not take in account the number of individuals that were away working (fishing boats, training with the Rangers), hunting or visiting (other communities or out-post camps); which often happens during the summer months. This may account for the fact that there were more female participants than males because the men are the predominant hunters and seasonal workers.
This limitation could have been addressed if for instance, the cross-sectional study was done during the fall or winter months. Despite these factors, the small size limited our statistical power resulting in a few statistically significant results and, also limits the generalizability of our results. As such, a similar study with a larger population size would certainly be warranted.
The second limitation was self-reporting. Self-reporting of sensitive information like previous STIs or number of sexual partners is subject to underreporting biases arising from personal concerns about social stigma, failure of recall, and even lack of knowledge that the respondent had a particular STI. Considerable effort was expanded in minimizing underreporting by devising an interview protocol that gave a maximum sense of privacy and confidentiality and provided memory aids to facilitate respondent recall. Secondly, certain questions (i.e., number of previous STIs and STI testing) were cross-referenced with chart reviews. The health centre charts however, only contained results that were obtained from screening tests done in the test community and not from other locations (e.g., Iqaluit, Ottawa, MTreal or other communities within the Baffin Region).
Despite these limitations, the results of this study support the use of universal screening, contact tracing and prompt treatment of positive individuals and their partners every 6 months especially, for communities with chlamydia prevalence greater than 10% as an effective means of decreasing prevalence and incidence and, overall disease burden. Universal screening is one method that would help normalize screening of STIs like chlamydia and gonorrhea among others, and would enhance the screening of individuals that would not traditionally be screened (e.g., males, adolescents and asymptomatic individuals) and essentially, help decrease STI transmission in small, closed populations and especially, within cohesive sexual networks.
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