Objectives Trichomonas vaginalis (TV) is the most common curable STI worldwide and is associated with increased risk of HIV acquisition and serious reproductive morbidities. The prevalence of TV infection is very low in Australian cities, and this is thought to be at least partly due to incidental detection and treatment of TV in women participating in the cervical cytology screening programme. In 2017, the national cervical screening programme will transition to a new model based on testing for high-risk (HR) human papillomavirus (HPV), with a reduced frequency and commencement at an older age. We model the potential impact of this transition on TV prevalence in Australia.
Methods A mathematical model was developed to describe the transmission of TV in the general population and used to evaluate scenarios that capture the switch from cytology-based screening to HR HPV testing. Under these scenarios, individuals with asymptomatic TV who test negative for HR HPV will remain undiagnosed and untreated. We estimate the change in TV prevalence expected to occur due to the switch from cytology to HR HPV testing and changes to the frequency and age at commencement of screening.
Results Our results suggest that with the transition to HR HPV testing, TV prevalence may increase from the current ~0.4% to 2.8% within 20 years if TV testing coverage is not increased and HR HPV prevalence does not decline further. If HR HPV prevalence continues to decline at its current rate with ongoing vaccination, TV prevalence is predicted to increase to 3.0% within this time frame.
Conclusions Our modelling suggests that in a setting like Australia, where TV can be detected incidentally through cytology-based cervical screening, a transition to HPV testing is likely to result in increasing TV prevalence over time unless additional measures are implemented to increase TV testing and treatment.
- mathematical model
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Handling editor Katy M E Turner
Contributors BBH and DGR developed and collaborated in the writing of the manuscript. BBH and CPR were involved in the design and implementation of the model. RJG, BD, JSH and MGL were involved in providing expert opinions on cervical screening and HPV. RB and JSH were involved in providing expert opinions on transmission of Trichomonasvaginalis and laboratory practice. All coauthors revised the manuscript before submission.
Funding DGR and BBH are supported by a National Health and Medical Research Council Program Grant (568971). The Kirby Institute is funded by the Australian government Department of Health and Ageing, and is affiliated with the Faculty of Medicine, University of New South Wales.
Disclaimer The views expressed in this publication do not necessarily represent the position of the Australian government.
Competing interests BBH reports grants from the National Health and Medical Research Council during the conduct of the study; CPR reports personal fees from The Kirby Institute during the conduct of the study; MGL reports grants from Boehringer Ingelhiem, Gilead Sciences, Merck Sharp & Dohme, Bristol-Myers Squibb, Janssen-Cilag, ViiV HealthCare, and personal fees from Gilead Sciences, Sirtex, outside the submitted work; DGR reports grants from the National Health and Medical Research Council during the conduct of the study; RJG, BD and JSH have nothing to disclose.
Provenance and peer review Not commissioned; externally peer reviewed.