SNAPSHOT HEALTH DEPARTMENT

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1 SNAPSHOT HEALTH DEPARTMENT August 2011 Chlamydia HIGHLIGHTS Chlamydia is a sexually transmitted infection that may go undetected because it is often asymptomatic. Chlamydia is the most reported sexually transmitted infection in Durham Region with approximately 1,250 cases of the disease reported in Chlamydia rates increased 1.6 fold in Durham Region since This increase is consistent with trends in Ontario, Canada and internationally. The number of tests completed at Durham Region Health Department sexual health clinics increased between 2006 and 2010 and the percent with positive results also increased. Rates were higher among Durham Region females than males, consistent with patterns for Ontario. Rates have been highest among young adults years old in Durham Region since Durham Region rates were lower than Ontario rates for all ages and genders except for adolescent males and females years of age and young adult males years of age. The largest increase in rates occurred among adults years of age. Rates for combined were five times higher among males and seven times higher among females than for combined. Within Durham Region, chlamydia rates were highest in Ajax, followed by Oshawa, Pickering, and Whitby. Medical services and day procedures for pelvic inflammatory disease, a consequence of untreated chlamydia, have been steadily decreasing among Durham Region females. Sexually active Durham Region males were more likely to report using a condom the last time they had sexual intercourse than females. Sexually active Durham Region adults aged were less likely to report using a condom the last time they had sexual intercourse as compared to those aged years. 89% of Durham Region residents aged years reported that they had only one sexual partner in the previous 12 months.

2 Chlamydia Overview Genital chlamydia is a sexually transmitted infection (STI) caused by the 1 intracellular bacterium Chlamydia trachomatis. Of significant concern is the asymptomatic nature of the infection, which has the potential for creating a reservoir for widespread transmission. After years of decline, in the past 12 2 years rates have increased in Durham Region, as well as across Canada. Currently, genital chlamydia is the most reported STI in Durham Region, as well as in Ontario. Contents... pages Chlamydia Overview...2 The Burden of Chlamydia in Durham Region...3 Overall Rates of Infection...3 By Sex...4 By Age By Municipality Health Consequences...6 Prevention Condom Use...7 Number and Type of Partners...8 What Does the Durham Region Health Department Do About Chlamydia?...9 Data Sources and Data Notes References Key Resources...12 Genital chlamydia is mainly transmitted through direct sexual contact via oral, 3 vaginal, or anal routes with an infected individual. Furthermore, newborns may be susceptible to vertical transmission from an infected mother during childbirth. Symptoms of genital chlamydia in females include pain during or after sexual 4 intercourse, pain or burning during urination, vaginal discharge, and fever. Similarly, males may experience discharge from the penis, burning sensation 5 while urinating, itching of the penis, and pain in the testicles. However, up to 70% of females and 50% of males who are infected with genital chlamydia 1 may show no overt clinical symptoms. This makes public health efforts particularly difficult since individuals who are asymptomatic have the potential to create a reservoir for widespread transmission, while escaping detection. Testing for chlamydia involves either a genital swab or a urine sample. Urine testing became available in 1996 and is particularly effective since it is noninvasive and has high sensitivity (94-99%) and specificity (98-100%) due to the use of nucleic acid amplification techniques (NAAT) using polymerase 6 chain reaction (PCR). In comparison, traditional enzyme immunoassay used in genital swabs has lower sensitivity (60-65%) and specificity (75-95%). Sensitivity Sensitivity is a measure of the probability of correctly diagnosing a case, or the probability that any given case will be identified by the test; also known 10 as the true positive rate. Specificity Specificity is a measure of the probability of correctly identifying a non- 10 diseased person with a test; also known as the true negative rate. A common approach to treating genital chlamydia is with oral antibiotics. The preferred approach is through a single dose of azithromycin or a 7 day course 7 of doxycycline. Efficacy and use-effectiveness studies have demonstrated similar cure rates between the two antibiotics. Although azithromycin is much more expensive, it is provided free of charge at Durham Region Health Department (DRHD) sexual health clinics and is the preferred treatment option because of higher compliance. It is important to note that although rare, drug 8,9 resistance is becoming an emerging issue with over-prescription. Ontario's case definition for Chlamydia trachomatis infections: Confirmed case Chlamydia trachomatis detected in an appropriate clinical 11 specimen (e.g., urogenital tract, rectal specimen). 2

3 The Burden of Chlamydia in Durham Region Overall rates of Infection Genital chlamydia was included as a 12,13 notifiable disease in Canada in Specifically, the Ontario Health Protection and Promotion Act requires genital chlamydia to be reported to the local 14 Medical Officer of Health. Durham Region experienced a decrease in the number and rate of reported cases of chlamydia from 1992 to 1997 (Figure 1). From 1997 to 2009, the trend reversed and age-standardized incidence rates progressively increased. Rates were consistently lower than for Ontario, which showed similar trends. The latest figures showed an incidence rate of 221 cases per 100,000 or 1,250 cases in 2009, which is a 1.6 fold increase since 1997 when there were 350 cases reported. Rate per 100, Figure 1: Chlamydia Age-Standardized Incidence, Durham Region & Ontario, Source: Integrated Public Health Information System, Durham Region, , Extracted February 2011; Integrated Public Health Information System, Ontario, Ontario Public Health Portal, , Accessed February 2011; Population Estimates, , intellihealth, Ministry of Health and Long-Term Care Durham Ontario 2009 Age-standardized incidence rate: The age-standardized incidence rate is an incidence rate that takes into account the age distribution of certain populations. For the purpose of this report, the 1991 Canadian population was used as the standard population. Time trends are difficult to interpret due to changes in reporting such as increased detection from laboratory improvements 15 and increased surveillance over time. In particular, the increase in incidence after 1997 may be due in part to the 16 introduction of the NAAT, which substantially increased sensitivity compared to swab testing. Moreover, testing of urine is less invasive and tolerable, which may result in more people, particularly males, getting tested. 17 Other explanations for the increased incidence rates have been suggested. It may be that increasingly more people are being screened for chlamydia, particularly, those at higher risk for the disease. As well, more effective contact tracing may be finding more cases. As a result, part of the increase in chlamydia rates may be due to Figure 2: Number of ChlamydiaTests and Percent Positive Results, changes in surveillance. Percent Positive 10% 9% 8% 7% 6% 5% 4% 3% 2% 1% 0% Durham Region Sexual Health Clinic Clients, # of Tests 2,004 2,177 2,740 2,710 2,715 Percent Postive 2.8% 3.7% 3.1% 4.8% 6.5% # Positive Source: Integrated Public Health Information System, Durham Region, , Extracted February 2011; Durham Region Health Department Sexual Health Clinic Database, , Extracted March ,000 2,500 2,000 1,500 1, Number of Tests In Durham Region, the number of chlamydia tests completed at DRHD sexual health clinics has increased since 2006 (Figure 2). The increase resulted from both an increase in the total number of visits to the clinic as well as an increase in the proportion of clients receiving chlamydia tests, from 21% in 2006 to 29% in In addition, the percentage of positive chlamydia lab results increased from 2.8% in 2006 to 6.5% in 2010, suggesting that clients at higher risk for the disease are being tested. These results also suggest that the increasing number of tests does not seem to account for all of the increase in chlamydia cases. This is 17 consistent with scientific literature. 3

4 By Sex In general, females are disproportionately more likely to be reported with genital chlamydia than males; this may be interpreted as females having a higher 5 incidence of chlamydia. However, it is unclear whether this is due to a difference in testing rates between sexes, resulting in under-diagnosing in males, rather than a true difference in incidence. Females are more likely to be tested for chlamydia during routine medical visits for birth control or Pap tests. In Durham Region, females accounted for approximately 66% of all reported chlamydia cases in 2009 or almost 830 cases. The annual incidence rate has remained lower than that for Ontario for Rate per 100, Figure 3: Chlamydia Age-Standardized Incidence Rates by Sex, Durham Region & Ontario, Durham Female Rate Ontario Female Rate Durham Male Rate Ontario Male Rate both males and females but continues to be the highest among females (Figure 3). This may reflect the combination of high screening rates during routine pelvic examinations and low testing rates in men. Among individuals who were tested for chlamydia at DRHD sexual health clinics in 2009, 75% were female. This proportion has decreased slightly from 81% in Between 2005 and 2010 an average of 96% of females receiving a Pap test at the DRHD sexual health clinics also received a chlamydia test. By Age Rate per 100,000 Figure 4: Chlamydia Incidence Rates by Age & Sex, Durham Region & Ontario, Combined Durham Males Durham Females Ontario Males Ontario Females Sources: Integrated Public Health Information System, Durham Region, , Extracted February 2011; Integrated Public Health Information System, Ontario, Ontario Public Health Portal, , Accessed February 2011; Population Estimates, , intellihealth, Ministry of Health and Long-Term Care Age Source: Integrated Public Health Information System, Durham Region, , Extracted February 2011; Integrated Public Health Information System, Ontario, Ontario Public Health Portal, , Accessed February 2011; Population Estimates, , intellihealth, Ministry of Health and Long Term-Care Younger age is associated with an 1 increased risk of chlamydia. Adolescents and young adults consistently have the highest incidence rates in Ontario, as 18 well as in Canada. There are a number of reasons for this; adolescents and young adults may be less likely to use 19 condoms, have more liberal attitudes 20 towards sexuality, and may not acknowledge the risks associated with 21 their sexual behaviours. In addition, adolescent females are at a greater risk 1 for acquiring genital chlamydia. During puberty, certain aspects of physical development, such as changes in vaginal flora and mucus production, increase the 19,22 vulnerability of females to STIs. In comparison, older females are more likely to build up partial immunity after initial or sequential infections in the past. Consistent with Ontario, the highest incidence rates were reported in adolescents and young adults in Durham Region (Figure 4). Rates were lower in Durham Region than Ontario for all ages and genders except for adolescent males and females years of age, and young adult males years of age. 4

5 As with overall rates, incidence increased since 1997 in all age groups (Figure 5). There were too few chlamydia cases reported among Durham Region adults aged 50 years or older and among adolescents under 15 to analyze annual trends in these age groups. Individuals within the age group had the highest rates of chlamydia compared to any other age group prior to 1994; however, this was surpassed by year olds in This trend may reflect the difficulties in providing sexual health education programs to young adults compared to the teen population. Although incidence rates were lowest among adults years of age, the largest increase in Rate per 100, Figure 5: Chlamydia Incidence Rates by Age, Durham Region, chlamydia rates during the past decade was seen in this age group. Rates for combined were five times higher among males and seven times higher among females than for combined (figure not shown). This trend was also found in Ontario data. Increasing rates in older adults may be associated with higher divorce rates, 23,24 increased availability of internet dating websites, and sexual risk taking behaviours Note: Age specific rates are suppressed when counts are less than 5, represented by a blank space in the graph. Sources: Integrated Public Health Information System, Durham Region, , Extracted February 2011; Population Estimates, , intellihealth, Ministry of Health and Long-Term Care By Municipality For 2007 to 2009 combined, chlamydia rates were highest in Ajax, followed by Oshawa, Pickering, and Whitby. Rates were lowest in Clarington and North Durham (Scugog, Brock, and Uxbridge) (Figure 6). Females consistently had the highest chlamydia rates across Durham Region municipalities compared to males. Oshawa followed by Ajax had the highest rates among females whereas Ajax followed by Pickering had the highest rates among males. North Durham had the lowest rates among both males and females. These patterns may reflect higher rates of testing and therefore higher detection of cases in the southern municipalities rather than simply higher rates of infection. Rate per 100, Figure 6: Chlamydia Incidence Rates by Muncipality & Sex, Durham Region, Combined Pickering Ajax Whitby Oshawa Clarington North Durham* Males Females Total Durham Region Municipality Sources: Integrated Public Health Information System, Durham Region, , Extracted February 2011; Population Estimates, , intellihealth, Ministry of Health and Long-Term Care *North Durham includes Brock, Port Perry, and Uxbridge 5

6 Health Consequences The consequences of untreated chlamydia infection in females include pelvic inflammatory disease (PID), which can lead to infertility, ectopic pregnancy, and chronic 1,25 pelvic pain. Sequelae for males may include chronic urethritis (urethral inflammation), epididymitis (inflammation of testicles), and prostatitis (prostate inflammation), which may lead to sterility and 3,4 difficulty passing urine. Most cases of PID are caused by bacteria, chlamydia or gonorrhea most commonly, that move from the vagina or cervix into the uterus, fallopian tubes, ovaries, or pelvis. From 2005 to 2009, medical services and day procedures for PID among females 15 year and older have been steadily decreasing in Durham Region (Figure 7). This may reflect changes in treatment practices where females with chlamydia and other STIs are being diagnosed and are seeking treatment earlier and preventing long term consequences such as PID. However, inpatient hospitalizations remained relatively stable indicating little change in these more serious cases. Finally, emergency department visits increased between 2007 and 2009; the reasons for this increase are unclear. Ontario data showed similar trends (figure not shown). Females who were between years old had the highest rates for PID consultations compared to any other age group for medical services, inpatient discharges, and day procedures (figure not shown). Similar trends were observed for Ontario. Figure 7: Health Services Visits for PID Among Females Aged 15 & Over, Durham Region, Rate per 100, Day Procedures ED Visits Medical Services Inpatient Discharges Source: Ambulatory Visits, Hospital In-Patient Data, Medical Services, Population Estimates, , intellihealth, Ministry of Health and Long-Term Care, Extracted March

7 Prevention Condom Use The use of barrier methods of contraception (i.e., condoms) has been shown to be associated with a reduced risk of infection compared 26,27 to oral contraceptives. Similarly, having unprotected sex in the past three months has been found to significantly increase the risk of contracting chlamydia compared to 28 those having protected sex. Results from the Canadian Community Health Survey (CCHS) show approximately 50% of Durham Region respondents aged had sexual intercourse during the past 12 months. There were no changes between 2003, 2005, and and Durham Region figures were relatively similar to those of Ontario (Figure 8). Percent sexually active* 60% 50% 40% 30% 20% 10% 0% Figure 8: Sexual Activity in the Past 12 Months, Durham Region & Ontario, 2003, 2005 & Durham 51% 53% 50% Ontario 48% 47% 44% Source: Canadian Community Health Survey 2003, 2005, & *Respondents include those years of age. Percent that used a condom** Figure 9: Condom Use by Sex, Durham Region & Ontario, 2003, 2005 & % 80% 70% 60% 50% 40% 30% 20% 10% 0% Durham Males 45% 50% 72% Durham Females 38% 50% 34% * * * Ontario Males 57% 61% 63% Ontario Females 49% 53% 50% Source: Canadian Community Health Survey 2003, 2005, & *Interpret with caution as coefficient of variation is between 16.6 and 33.3%. **Respondents include those years of age who were sexually active in the past 12 months, not currently married or in a common-law relationship, and who had more than one partner in the past 12 months. Respondents to the CCHS who were sexually active in the past 12 months, not currently married or in a common-law relationship, and who had more than one partner in the past 12 months were asked about condom use. In , 72% (95%CI: 55-84%) of Durham Region males and 34% (95%CI: 19-53%) of Durham Region females used a condom the last time they had sexual intercourse (Figure 9). Although this difference was significant for Durham Region only in , Ontario data showed that males were significantly more likely than females to report using a condom the last time they had sexual intercourse in all time periods. Although condom use among Durham Region males increased from 2003 (45%, 95%CI: 31-60%) to (72%, 95%CI: 55-84%), the increase was not statistically significant. Ontario estimates showed a similar pattern (57%, 95%CI: 53-61% vs. 63%, 95%CI: 59-66%). 7

8 Percent that used a condom** 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Figure 10: Condom Use by Age, Durham Region & Ontario, Durham 84% 73% 27% * Ontario 79% 69% 43% Age Source: Canadian Community Health Survey *Interpret with caution as coefficient of variation is between 16.6 and 33.3%. **Respondents include those years of age who were sexually active in the past 12 months, not currently married or in a common-law relationship, and who had more than one partner in the past 12 months. Condom use decreased with age in Durham Region and Ontario (Figure 10). In particular in , only 27% (95%CI: 15-44%) of Durham Region adults years old used a condom the last time they had sexual intercourse, compared to 78% (95%CI: 61-89%) of year olds. Similar numbers were seen for Ontario and in the 2003 and 2005 CCHS. A contributing factor may be the fact that this group is largely excluded from prevention 23 programs. Furthermore, many older adults who have come out of long-term relationships feel contraception is no longer an issue, contributing to the infrequent use of 29 condoms among older adults. Number and Type of Partners Sexual activity with multiple partners increases the probability of encountering an infected partner. The risk of being infected with chlamydia has been found to increase with the number of lifetime sexual partners 30 that females have. Moreover, having new or casual sexual contacts is associated with increased risk, possibly due to a reduced familiarity 31 of sexual history between partners. In the CCHS the majority of individuals in Durham Region aged who were sexually active in the past 12 months (89%, 95%CI: 85-92%) indicated having only one sexual partner in that past year (Figure 11). Results were comparable to Ontario data. Percent of sexually active** 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Figure 11: Number of Sexual Partners in the Past 12 Months, Durham Region & Ontario, Partner 2 Partners 3 Partners 4+ Partners Durham 89% 5.8% 2.7% 2.7% * * * Ontario 87% 6.4% 3.3% 3.1% Source: Canadian Community Health Survey *Interpret with caution as coefficient of variation is between 16.6 and 33.3%. **Respondents include those years of age. Number of Partners 8

9 What is Durham Region Health Department Doing About Chlamydia? Durham Region Health Department operates sexual health clinics in Oshawa, Pickering, and Port Perry. These clinics offer assessment, counseling and treatment as well as referral services for STIs. Clinics also provide services to contacts of confirmed STI cases. HIV testing and counseling, for both anonymous and Point of Care, is available. Free condoms are supplied at all clinics and antibiotics for treatment of STIs are provided at no cost. Individuals considered at risk for hepatitis B are offered hepatitis B vaccine. Anyone can book an appointment for clinics. All information shared is kept private and confidential. In addition, DRHD promotes healthy approaches to prevent the spread of STIs in the community. Curriculum support resources are being developed in collaboration with teachers in Durham Region. Clinic information is provided to health care providers, community agencies and school boards to increase awareness in individuals of services available. DRHD receives reports of all positive chlamydia cases and implements surveillance activities, including the collection, analysis, interpretation, and dissemination of information. DRHD records case and contact management information on iphis, a provincial reporting database. In addition to collaborating with physicians to ensure case management meets Canadian and provincial guidelines, DRHD provides education and counseling to confirmed cases of chlamydia and other STIs, including prevention, transmission, risk of complications as well as assisting in partner notification and follow-up. Data Sources and Data Notes Population Estimates Source: Ontario Population Estimates, , Ontario Ministry of Health and Long-Term Care, intellihealth ONTARIO, Extracted: October Reportable Disease Data Source: integrated Public Health Information System (iphis), Durham Region, , Extracted: March Each board of health is responsible for collecting case information on reportable communicable diseases. This information is summarized for provincial and national surveillance. Physicians, nurses, other regulated health professionals, hospitals and laboratories are required by law to report all cases of chlamydia to the local medical officer of health. This information is collected in iphis (Reportable Disease Information System (RDIS) prior to 2005) and is kept strictly confidential. The most common source of case identification is through laboratory notification of confirmed test results (serology, microbiology cultures, etc.). There may be considerable under-reporting of cases because an infected person with mild or no clinical symptoms may not seek medical care and/or laboratory testing may not be performed. Ontario iphis data for are preliminary and therefore subject to change. These data have not been cleaned and may also include duplicate cases. Sexual Health Clinic Data Source: DRHD Sexual Health Clinic Database, , Extracted: March DRHD maintains information about all clients attending their sexual health clinics in an MS Access database. The database does not contain any identifying information about clients but captures details of their visit and services received for the purposes of program monitoring, planning and evaluation. 9

10 Data Sources and Data Notes Canadian Community Health Survey (CCHS) Source: Canadian Community Health Survey, 2003, 2005 and , Statistics Canada, Share File, Ontario Ministry of Health and Long-Term Care. The CCHS is a federal survey conducted by Statistics Canada to provide cross-sectional health information at regional, provincial, and national levels. The target population of the CCHS is residents aged 12 years and older in all provinces and territories, excluding populations on Indian Reserves, Canadian Forces Bases, and some remote areas. Data collection is done by a combination of computer-assisted personal and telephone interviewing. Estimates with counts less than 10 or a bootstrap coefficient of variation (C.V.) greater than 33.3% have been suppressed. Estimates with a C.V. of % have been identified as marginal and should be used with caution because they are based on a small number of respondents and have high sampling variability. The 95% confidence interval (CI) is used to reflect the amount of variability or precision that is around an estimate, such as an odds ratio. Smaller CIs indicate greater precision, usually as a result of a larger sample size. The confidence intervals presented can be interpreted as being 95% likely to include the true value if every resident was surveyed. In charts, the 95% confidence interval is represented by an error bar ( I ) around each point or bar. A statistically significant difference means the difference is not likely due to chance and refers to a difference between two percentages where the confidence intervals do not overlap. Hospitalization Data Source: Hospital In-Patient Data, , Ontario Ministry of Health and Long-Term Care, IntelliHEALTH ONTARIO, Extracted: March In-patient hospitalization data capture all hospital separations; a separation may be due to discharge home, death or transfer to another facility. The most responsible diagnosis (MRD) is the one diagnosis which describes the most significant condition of the patient which caused the stay in hospital. The International Classification of Diseases (ICD), specifically ICD-10-CA is used to code the diagnosis. All hospitalizations for PID were selected using ICD-10- CA codes N70-N74 (includes salpingitis and oophoritis; inflammatory disease of uterus, except cervix; Inflammatory disease of cervix uteri; other female pelvic inflammatory diseases; and female pelvic inflammatory disorders in diseases classified elsewhere) as the MRD. Ambulatory Care Data Source: Ambulatory Visits, , Ontario Ministry of Health and Long-Term Care, IntelliHEALTH ONTARIO, Extracted: March Ambulatory care data representing utilization of ambulatory services in Ontario's hospitals includes but is not limited to emergency department (ED) visits and day surgery visits. The patient's main problem or diagnosis is coded using ICD-10-CA. ED visits and day surgery visits for PID were selected using ICD-10-CA codes N70-N74 (includes salpingitis and oophoritis; inflammatory disease of uterus, except cervix; Inflammatory disease of cervix uteri; other female pelvic inflammatory diseases; and female pelvic inflammatory disorders in diseases classified elsewhere) as the main problem. Medical Services Visits Source: Medical Services, , Ontario Ministry of Health and Long-Term Care, IntelliHEALTH ONTARIO, Extracted: March Medical services information in IntelliHEALTH ONTARIO is obtained from the Ontario Health Insurance Plan (OHIP) Approved Claims file. This file contains service and payment information for both feefor-service claims submitted by physicians and other licensed health professionals and some of the shadow billings by providers in organizations covered by alternate payment arrangements. Diagnoses are coded using OHIP Diagnosis Codes, a coding system unique to OHIP and based on loosely on the ICD. All medical service visits for PID were selected using OHIP Diagnosis Codes 614 (includes acute or chronic salpingitis, oophoritis or abscess, pelvic inflammatory disease) & 615 (includes acute or chronic endometritis). This combination of codes likely underreports visits for PID since some of the visits coded as 616 (includes cervicitis, vaginitis, cyst or abscess of bartholin's gland, vulvitis), cervicitis in particular, could also have a diagnosis of PID. In addition OHIP does not collect any geographic information on the patient, therefore residence of the patient is based on their address recorded in the Registered Persons Database and many of these have not been updated since they were first entered in the early 1990's. 10

11 References 1. Navarro C, Jolly A, Nair R, Chen Y. Risk factors for genital chlamydial infection. Can J Infect Dis May;3(3): York Region Community and Health Services. Chlamydia and Gonorrhea Focus Report. Newmarket: York Region; [cited 2011 February]. Available from: fu3blpzmk75chh/sti+focus+report+web.pdf. 4. Kwong JC, Crowcroft NS, Campitelli MA, Ratnasingham S, Daneman N, Deeks SL, Manuel DG. Ontario burden of infectious disease study advisory group; Ontario Burden of Infectious Disease Study (ONBOIDS): An OAHPP/ICES reprt. Toronto: Ontario Agency for Health Protection and Promotion, Institute for Clinical Evaluative Sciences; Wong T, Singh A, Mann J, Hansen L, McMahon S. Gender differences in bacterial STIs in Canada. BMC Women's Health Aug 25;4(Suppl 1):S Weir E. Upsurge of genital Chlamydia trachomatis infection. CMAJ Oct 12 [cited 2011 February];171(8):855. Available from: 8. Somani J, Bhullar VB, Workowski KA, Farshy CE, Black CM. Multiple drug-resistant Chlamydia trachomatis associated with clinical treatment failure. J Infect Dis Apr;181: Misyurina OY, Chipitsyna EV, Finashutina YP, Lazarev VN, Akopian TA, Savicheva AM, Govorun VM. Mutations in a 23S rrna gene of Chlamydia trachomatis associated with resistance to macrolides. Antimicrob Agents Chemother Apr;48: th 10. Last JM. A Dictionary of Epidemiology. 4 ed. New York: Oxford University Press; Ontario Ministry of Health and Long-Term Care. Infectious Diseases Protocol, Appendix B: Provincial Case Definitions for Reportable Diseases. Toronto, ON: Queen's Printer for Ontario; 2009 [cited 2011 May 24]. Available from: progstds/idprotocol/appendixb/appendix_b.pdf. 13. Doherty J. Establishing priorities for national communicable disease surveillance. Can J Infect Dis Med Microbiol Jan;11(1): Public Health Agency of Canada. Report on sexually transmitted infections in Canada. Ottawa: Public Health Agency of Canada; 2008 [cited 2011 March]. Available from: 7. Public Health Agency of Canada. Canadian Guidelines on Sexually Transmitted Infections. Ottawa: Public Health Agency of Canada; 2010 [cited 2011 February]. Available from: Public Health Agency of Canada Canadian Sexually Transmitted Infections Surveillance Report. CCDR [cited 2011 February];33S1: Available from: Health Protection and Promotion Act, R.S.O [cited June 2011], c. H.7, s.25. Available from: Rekart ML, Brunham RC. Epidemiology of Chlamydia infection: are we losing ground. Sex Transm Infect Apr;84: Miller WC. Epidemiology of Chlamydia infection: are we losing ground. Sex Transm Infect Apr;84:

12 Key Resources Durham Region Health Department. Focused report on Adolescent Sexual Health: health/health_statistics/focused reportadolescenthealth.pdf Durham Region Health Department. Infectious Diseases at a Glance: health/health_statistics/infectious diseaseataglance.pdf Health Canada, Chlamydia: public/pub/std/shlam.html Ontario Ministry of Health and Long- Term Care. Sexually Transmitted Diseases, Chlamydia public/pub/std/chlam.html Public Health Agency of Canada. Sexual transmitted Infections Pamphlet, Chlamydia: /std-mts/chlam-eng.php For more information, contact: DURHAM REGION HEALTH DEPARTMENT 605 Rossland Road East (905) or Fax: (905) References 17. Vickers DM, Osgood ND. Current crisis or artifact of surveillance: insights into rebound chlamydia rates from dynamic modeling. BMC Infectious Diseases Mar 16;10(70): Division of Sexual Health Promotion and STD Prevention & Control. STD Data Tables: Reported Genital Chlamydia Cases and Rates in Canada by Age Group and Sex, Ottawa: Bureau of HIV/AIDS, STD & TB, Health Canada; Berman SM, Hein K. Adolescents and STDs. In: Aral SO, Sparling PF, Mardh PA et al, eds. Sexually Transmitted Diseases. New York, McGraw-Hill; P Panchaud C, Singh S, Feivelson D, Darroch JE. Sexually Transmitted Diseases among Adolescents in Developed Countries. Fam Plann Perspect. 2000;32(1): Cates W. The epidemiology and control of sexually transmitted diseases in adolescents. J Adol Health Care Oct 1;1(3): Bolan GA, Ehrhardt AA, Wasserheit JN. Gender perspectives and STDs. In Holmes KK, Sparling PF, Mardh PA, Lemon SM, Stamm WE, Piot P et al., editors. Sexually transmitted diseases. New York: McGraw-Hill, P Bodley-Tickell AT, Olowokure B, Bhaduri S, White DJ, Ward D, Ross JDC, Smith G, Duggal HV, Goold P. Trends in sexually transmitted infections (other than HIV) in older people: analysis of data from an enhanced surveillance system. Sex Transm Infect Aug;84: Jena AB, Holdman DP, Kamdar A, Lakdawalla DN, Lu Y. Sexually transmitted diseases among users of erectile dysfunction drugs: analysis of claims data. Ann Intern Med Jul 6;152: Haggerty CL, Gottlieb SL, Taylor BD, Low N, Xu F, Ness RB. Risk of sequelae after Chlamydia trachomatis genital infection in women. J Infect Dis Jun 15;201(S2):S Harrison H, Costin M, Meder J, et al. Cervical Chlamydia trachomatis infection in university women: Relationship to history, contraception, ectopy, and cervicitis. Am J Obstet Gynecol Oct 1;153: Mosure DJ, Berman S, Kleinbaum D, Halloran ME. Predictors of Chlamydia trachomatis infection among female adolescents: A longitudinal analysis. Am J Epidemiol Nov 15;144: Han Y, Coles F, Hipp S. Screening criteria for Chlamydia trachomatis in family planning clinics: Accounting for prevalence and clients' characteristics. Fam Plann Perspect Jul-Aug;29: Jaleel H, Allan S, Wade AAH. Sexually transmitted infections in the elderly. Sex Transm Inf Dec 7;75: McCormack WM, Rosner B, McComb DE, Evrard JR, Zinner SH. Infection with Chlamydia trachomatis in female college students. Am J Epidemiol Jan;121: Laumann EO, Gagnon JH, Michael RT, Michaels S. The social organization of sexuality: Sexual practices in the United States. Chicago: The University of Chicago Press; Information available in alternate formats. Aug. 2011