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RESEARCH ARTICLE (Open Access)

Epidemiology of notified chlamydia infections, Queensland, 2000–2019

Troy A. Laidlow https://orcid.org/0000-0003-3360-9309 A B * , Kathleen Lynch https://orcid.org/0000-0001-8335-8259 C , Satyamurthy Anuradha https://orcid.org/0000-0002-1006-7191 D , Craig Thompson E , Davoud Pourmarzi A F , Jane Hocking https://orcid.org/0000-0001-9329-8501 G and Stephen B. Lambert https://orcid.org/0000-0002-2709-193X B
+ Author Affiliations
- Author Affiliations

A Australian National University, National Centre for Epidemiology and Population Health, Canberra, ACT, Australia.

B Communicable Diseases Branch, Queensland Health, Brisbane, Qld, Australia.

C The University of Queensland, Centre for Clinical Research, Brisbane, Qld, Australia.

D The University of Queensland, School of Public Health, Brisbane, Qld, Australia.

E Queensland Infection Prevention and Control Unit (QIPCU), Brisbane, Qld, Australia.

F Guilan University of Medical Sciences, Rasht, Iran.

G University of Melbourne, Centre for Epidemiology and Biostatistics, Carlton, Vic, Australia.

* Correspondence to: troy.laidlow@aff.gov.au

Handling Editor: Somesh Gupta

Sexual Health 22, SH25121 https://doi.org/10.1071/SH25121
Submitted: 10 July 2025  Accepted: 1 September 2025  Published: 23 September 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Background

Chlamydia infection is a frequently reported notifiable condition in Queensland, with the highest prevalence observed among young people. Infection can occur in several sites including the anus, eye, pharynx, cervix/vagina, and urethra. Currently, historical trends in chlamydia by site of infection in Queensland are unknown.

Methods

A descriptive analysis of all chlamydia notifications in Queensland, 2000–2019, was performed. Queensland Health statewide notification data were classified as either anorectal, eye, genitourinary, upper respiratory tract, or other/unspecified. The number of chlamydia tests and proportion of tests positive for chlamydia were calculated using Medicare online testing data. Population denominator values were obtained from the Australian Bureau of Statistic’s catalogues.

Results

Over the 20-year period, chlamydia notifications increased, particularly among individuals aged 20–24 years. However, there was a noticeable decline in genitourinary notifications among those aged 15–19 years since 2010. Despite increased testing, the ratio of positive specimens to testing decreased among females aged 15–24 years.

Conclusions

Across the period of our study, there was a substantial and sustained decline in chlamydia notifications in those aged 15–19 years. Further research is required to understand factors that have contributed to this decrease and to guide programs for controlling chlamydia.

Keywords: adolescents, chlamydia, Chlamydia trachomatis, epidemiology, notifiable conditions, Queensland, sexually transmitted infections, surveillance.

References

Australian Government Department of Health and Aged Care. Chlamydia – laboratory case definition (LCD). Canberra: Australian Government Department of Health and Aged Care; 2009. Available at https://www.health.gov.au/resources/publications/chlamydia-laboratory-case-definition?language=en [cited 7 January 2024]

Australasian Sexual Health Alliance. Australian STI management guidelines for use in primary care: Chlamydia. Sydney: The Australasia Society for HIV, Viral Hepatitis, and Sexual Health Medicine (ASHM); 2018. Available at https://sti.guidelines.org.au/sexually-transmissible-infections/chlamydia/ [cited 7 January 2024]

Kirby Institute. Detailed sexually transmissible infection dashboards: Chlamydia. Sydney: Kirby Institute, UNSW Sydney; 2024. Available at https://www.data.kirby.unsw.edu.au/sexually-transmissible-infections [cited 17 December 2024]

National Centre in HIV Epidemiology and Clinical Research. HIV/AIDS, viral hepatitis and sexually transmissible infections in Australia Annual Surveillance Report 2001. Sydney: National Centre in HIV Epidemiology and Clinical Research, The University of New South Wales; 2001.

Australian Government Department of Health and Aged Care. Trachoma: CDNA national guidelines for the public health management of trachoma. Canberra: Australian Government Department of Health and Aged Care; 2014. Available at https://www.health.gov.au/sites/default/files/documents/2020/02/trachoma-cdna-national-guidelines-for-public-health-units.pdf [cited 7 January 2024]

Office of the Queensland Parliamentary Counsel. Public health act 2005. Brisbane: Office of the Queensland Parliamentary Counsel; 2023.

Office of the Queensland Parliamentary Counsel. Public health regulation 2018. Brisbane: Office of the Queensland Parliamentary Counsel; 2018.

Australian Government Department of Health and Aged Care. Chlamydial infection – Surveillance case definition. Canberra: Australian Government Department of Health and Aged Care; 2023. Available at https://www.health.gov.au/resources/publications/chlamydial-infection-surveillance-case-definition?language=en [cited 7 January 2024]

Australian Bureau of Statistics. National, state and territory population. Canberra: Australian Bureau of Statistics; 2020.

10  Australian Government Services Australia. Medicare item reports. Canberra: Australian Government Services Australia; 2022.

11  Chow EP, Fehler G, Read TRH, Tabrizi SN, Hocking JS, Denham I, et al. Gonorrhoea notifications and nucleic acid amplification testing in a very low-prevalence Australian female population. Med J Aust 2015; 202(6): 321-323.
| Crossref | Google Scholar | PubMed |

12  Parra-Sánchez M, Palomares JC, Bernal S, González MT, Sivianes N, Pérez L, Pueyo I, Martín-Mazuelos E. Evaluation of the cobas 4800 CT/NG test for detecting Chlamydia trachomatis and Neisseria gonorrhoeae DNA in urogenital swabs and urine specimens. Diagn Microbiol Infect Dis 2012; 74(4): 338-342.
| Crossref | Google Scholar | PubMed |

13  Fisher C, Kauer S. National survey of Australian secondary students and sexual health 1992–2018: trends over time. Bundoora: Australian Research Centre in Sex, Health & Society, La Trobe University; 2019.

14  Jung J, Biezen R, Goller JL, Hocking J, Chondros P, Manski-Nankervis J. The chlamydia care cascade of young people attending Australian general practices; a descriptive study to assess gaps in care. Sex Health 2023; 20(6): 542-549.
| Crossref | Google Scholar | PubMed |

15  US Centers for Disease Control and Prevention. Sexually transmitted infections treatment guidelines. US Centers for Disease Control and Prevention; 2021. Available at https://www.cdc.gov/std/treatment-guidelines/screening-recommendations.htm [cited 13 March 2024]

16  Australian Government Department of Heath and Aged Care. Fourth national sexually transmissible infections strategy 2018–2022. Canberra: Australian Government Department of Health and Aged Care; 2018.

17  Queensland Government Queensland Health. Queensland sexual health strategy 2016. Brisbane: Queensland Government Queensland Health; 2016.