Nicola Stephens

Public health policies and management strategies for genital Chlamydia trachomatis infection

Genital Chlamydia trachomatis is a sexually transmissible bacterial infection that is asymptomatic in the majority of infected individuals and is associated with significant short-term and long-term morbidity. The population prevalence of the infection appears to be increasing. C. trachomatis is of public health significance because of the impacts of untreated disease on reproductive outcomes, transmission of other sexually acquired infections, and the costs to health systems. At the individual level, C. trachomatis infection is readily treatable with antibiotics, although antibiotic resistance appears to be increasing. At the population level, public health control of spread of infection is more problematic. Approaches to control include primary preventive activities, increased access to testing and treatment for people with or at risk of infection, partner notification and treatment, and screening either opportunistically or as part of an organized population screening program. A combination of all of the above approaches is likely to be required to have a significant effect on the burden of disease associated with genital chlamdyia infection and to reduce population prevalence. The development of a vaccine for genital chlamydia infection could significantly reduce the public health burden associated with infection; however a vaccine is not expected to be available in the near future.

Chlamydia trachomatis in Tasmania 2001-2007: rising notification trends

Objectives: To investigate trends in notification rates of Chlamydia trachomatis in Tasmania, Australia, by population sub‐groups, from 1 January 2001 to 31 December 2007.

Improving public health surveillance of chlamydia: analysis of population-level positivity trends

UNLABELLED Background Chlamydia remains Australias most frequently notified communicable disease; however, interpretation of notification data is difficult without knowledge of testing practices. This study examined the value of reporting positivity trends. METHODS Tasmanian population-level chlamydia laboratory tests and notification data from 2001 to 2010 were compared. RESULTS Notifications, tests and positivity increased, most significantly in males and females aged 15-29 years. CONCLUSIONS Analysis of chlamydia positivity trends can inform the development, monitoring and evaluation of prevention and control activities and improves the interpretation of notification trends. After allowing for testing effort, an increase in chlamydia infections in young people was found.

Epidemic forecasts as a tool for public health: interpretation and (re)calibration

Objective: Recent studies have used Bayesian methods to predict timing of influenza epidemics many weeks in advance, but there is no documented evaluation of how such forecasts might support the day‐to‐day operations of public health staff.

Testing for chlamydial infection: are we meeting clinical guidelines? Evidence from a state-level laboratory data linkage analysis for 15- to 29-year-olds

Background Clinical guidelines recommend annual chlamydia tests for all sexually active people aged 15-29 years. This study measured adherence to these guidelines and compared testing rates to the projected levels required to reduce chlamydia prevalence. METHODS All chlamydia tests conducted in Tasmania during 2012-13, for residents aged 15-29 years, were linked. Data linkage allowed individuals who had multiple tests across different healthcare settings to be counted only once each year in analyses. Rates of testing and test positivity by age, sex, rebate status and socioeconomic indicators were measured. RESULTS There were 31899 eligible tests conducted in 24830 individuals. Testing coverage was higher in females (21%, 19404/92685) than males (6%, 5426/98123). Positivity was higher in males (16%, 862/5426) than females (10%, 1854/19404). Most tests (81%, 25803/31899) were eligible for a rebate. Positivity was higher in females with non-rebatable tests (12%, 388/3116 compared with those eligible for a rebate (9%, 1466/16285). More testing occurred in areas of middle disadvantage (10%, 9688/93678) compared with least (8%, 1680/21670) and most (10%, 7284/75460) (both P<0.001) disadvantaged areas. Higher test positivity was found in areas of most-disadvantage (11%, 822/7284) compared with middle- (10%, 983/9688) and least- (8%, 139/1680) disadvantaged areas. CONCLUSIONS Chlamydia testing rates are lower than recommended levels. Sustaining the current testing rates in females aged 20-24 years may reduce population prevalence within 10 years. This study meets key priorities of national strategies for chlamydia control by providing a method of monitoring testing coverage and evidence to evaluate prevention programs.

Chlamydia retesting and retest positivity rates: results from a state-wide laboratory data linkage study in Tasmania, 2012–13

Background Chlamydia re-infection increases the likelihood of adverse long-term sequelae. Clinical guidelines recommend retesting at 3-12 months for individuals with positive results, to detect re-infections. Retesting and test positivity levels were measured in young people who previously tested positive for chlamydia infection. METHODS All chlamydia tests conducted during 2012-13 in Tasmanian residents aged 15-29 years were linked. Retesting and retest positivity rates were calculated by sex, age, socioeconomic indicators and test timeframe. RESULTS Retesting rates were higher in females than males at 3 months (14.5%, n=242/1673 vs 10%, n=71/721) (P<0.01) and 12 months (27%, 265/968 vs 24%, 98/410) (P=0.24). The retesting rate was higher in females living in areas of most disadvantage (35.5%, 154/434) compared with areas of middle and least disadvantage (26% 139/534) (P<0.01). Males were more likely than females to retest positive at 3 months (35%, 25/71 vs 23%, 55/242) (P<0.01); retest positivity at 12 months was 32% in both sexes (males 98/140; females 265/968). Retest positivity was higher in males living in areas of least disadvantage (43%, 3/7) compared with middle (24%, 16/67) (P=0.27) and most (27%, 10/37) (P=0.09); and higher in females living in areas of least disadvantage (39%, 7/18) compared with middle (24%, 29/121) (P<0.01) and most (31%, 48/154) (P=0.02). CONCLUSIONS Retesting rates are low in Tasmania and retest positivity is high, reinforcing the importance of promoting safer sex practices, partner notification and treatment, and retesting.

Geographical differences in Chlamydia trachomatis testing in 15-29 year-olds in Tasmania: Findings from a statewide laboratory data linkage study.

Clinical guidelines for testing for Chlamydia tra- chomatis (chlamydia) infection recommend annual screening of all sexually active people aged 15 to 29 years. 1 Lower chlamydia testing rates have been reported in areas in Australia with less access to ser- vices. 2 The Australian Bureau of Statistics’ (ABS) Remoteness Structure of the Australian Standard Geo- graphical Standard divides Australia into regions that share common characteristics of remoteness. 3 Under the ABS structure, Tasmania has no major cities and its mainland population is classified as residing mostly in inner (65%) and outer (33%) regional areas with a small proportion (1.5%) residing in remote areas. 3 Due to its small geographical size compared to other Australian states, it has been suggested that chlamydia testing rates in Tasmania are less influenced by geo- graphical location; 4 however, this has not been previ- ously explored at a state-wide level. The aim of this study was to describe geographical differences in chlamydia testing in young people in regional and remote Tasmania to inform clinical practice.

Exploration of testing practices and population characteristics support an increase in chlamydia positivity in Tasmania between 2001 and 2010

Objective: The proportion of positive chlamydia tests in young people in Tasmania increased significantly between 2001 and 2010. While female positivity rates increased steadily, male positivity rose steeply to 2005 then stabilised. Crude positivity rates can be influenced by a variety of factors making interpretation difficult. Unique Tasmanian datasets were used to explore whether symptom status, reason for testing or sexual exposure could explain the observed positivity trends.