Urine as a sample type to understand Chlamydia prevalence in the Belgian population
Chlamydia prevalence is underrepresented
Chlamydia trachomatis (C. Trachomatis), known as chlamydia, is a common sexually transmitted infection (STI). However, as most infections are asymptomatic, they are commonly underdiagnosed. For example, in Europe the distribution and prevalence of chlamydia infections is expected to be higher than reported as many asymptomatic infections are not detected.
Current screening programs are mainly focused on young women between the ages 18 and 25 due to complications and long-term implications the infection can have on reproductive health. Less is understood about the spread in older women and men in general as these groups are not tested for as regularly.
Estimation of prevalence of the infection and its distribution across various ages and genders can help better design prevention and control programs, as well as understand sexual transmission patterns (1).
Belgium study uses urine to understand Chlamydia prevalence across population
In Belgium, routine screening for chlamydia is recommended for sexually active teens and young adults between ages 15–29 as well as for specific high-risk groups such as men who have sex with men.
To better understand the prevalence of genital Chlamydia across all population groups, Sciensano (the Belgian Institute for Health) set-up two studies between 2018-2020. The studies included a representative sample of mixed ages (16–59 years), genders and regions to participate in the screening program (1).
How did the study work?
Both studies used urine samples to analyze for presence of C. trachomatis DNA. Samples were tested at the Institute for Tropical Medicine, Antwerp.
In the first study, a total of 770 participants were included, and in the second, 763 participants. Participants were also asked to provide information about their socio-economic background, and sexual history, to help gain more insights and identify potential risk factors associated with the infection (1).
Participants received a test kit, which included Novosanis’ urine collection device, Colli-Pee®, and instructions for use (1). Colli-Pee® is a self-collection device that allows for volumetric and standardized first-void urine collection (2). A first-void urine specimen has shown to contain higher concentrations of chlamydia than other fractions, highlighting the importance of collecting this fraction of urine for improved diagnostic accuracy. Colli-Pee® also offers better patient comfort compared to a regular urine cup (3).
What were the results of the study?
Through these population-wide prevalence studies using urine, it was shown that overall prevalence of genital chlamydia is low in Belgian population. It was estimated that weighted prevalence of genital chlamydia is 1.54% for the Belgian population between ages 16–59 in study 1 and 1.76% for the population between ages 18–59 years in study 2. No difference in distribution was seen by gender, with a reported prevalence of 1.75–2.25% in men and 1.29–1.32% in women. These results are comparable to other similar studies in Europe (1).
Additionally, the results showed that there was a significant link between increased sexual partners (>3 in the past 12 months), as well as casual sexual relationships and infection rates.
Urine as a sample type is promising in STI-related research
The overall low prevalence and the wide distribution range in age and gender of chlamydia in the general Belgian population can help design and set-up future strategies for screening and prevention. While screening is primarily focused on young females, the results of the study highlight that male populations as well as women over 35 should be considered (1).
This type of study can also be extended to better understand the distribution and prevalence of other STIs. In this regard, first-void urine collected with Colli-Pee® is an exciting approach. Urine collection with the device is simple and can be performed independently at home, avoiding the need for a clinician. This offers the potential to reach a larger group, especially those who would typically not visit a clinic for testing.
Fischer N, Peeters I, Klamer S, Montourcy M, Cuylaerts V, Van Beckhoven D, De Baetselier I, Van der Heyden J, Vanden Berghe W. Prevalence estimates of genital Chlamydia trachomatis infection in Belgium: results from two cross-sectional studies. BMC Infect Dis. 2021 Sep 14;21(1):947. doi: 10.1186/s12879-021-06646-y. PMID: 34521367.
US Preventive Services Task Force, Davidson KW, Barry MJ, Mangione CM, Cabana M, Caughey AB, Davis EM, Donahue KE, Doubeni CA, Krist AH, Kubik M, Li L, Ogedegbe G, Pbert L, Silverstein M, Simon MA, Stevermer J, Tseng CW, Wong JB. Screening for Chlamydia and Gonorrhea: US Preventive Services Task Force Recommendation Statement. JAMA. 2021 Sep 14;326(10):949-956. doi: 10.1001/jama.2021.14081. PMID: 34519796.
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