Prevalence And Risk Factors Of Chlamydia In Hong Kong: A Population-based Geospatial Household Survey And Testing

Abstract

Chlamydia causes infertility and increases the risk of HIV infection, and population-based studies provide essential information for effective infection control and prevention. This study examined chlamydia prevalence and risk factors among a representative sample of 18-49-year-old residents in Hong Kong. Methods: City map of 412 constituency areas were used to construct a sampling frame as primary sampling units and, buildings and residential units were randomly selected using geospatial modeling software. A questionnaire on sexual health and practice was conducted between November 2014 and March 2016, and PCR was used to test the urine for genital chlamydia infection. Prevalence data was weighted according to the 2011 census and risk factors identified through logistic regression. Results: Among the 881 participants (response rate of 24.5%), the overall chlamydia prevalence was 1.4% (95%CI 0.8-2.4%) with those of the males and females at 1.1% (95%CI 0.4-2.8%) and 1.7% (95%CI 0.9-3.1%) respectively. Sexually active women aged 18-26 years had a particularly high chlamydia prevalence (5.3%, 95%CI 1.5-17.1% ). Amongst them, the risk factors of chlamydia infection were younger age (18-26 years; aOR=10.2, 95% CI 1.68 – 62.1); living with fewer people (i.e. 2 or below) (aOR = 3.09, 95% CI 1.10 - 8.73); or, those whose partners had travelled outside Hong Kong in the past 12 months (aOR=5.15, 95% CI 1.21 - 22.0).A core-peripheral distribution of chlamydia prevalence was observed in the territory. Conclusion: Young women have high chlamydia prevalence in Hong Kong. Routine screening for sexually active women aged 18-26 years should be considered. Further research on testing feasibility and linkage to care are urgently needed to reduce sexual risks of the population.