Systematic STI screening in unaccompanied migrant minors: a 6-year experience with urine-based NAAT

Systematic screening for sexually transmitted infections (STI), beyond serology, is not standard in arrival protocols for unaccompanied migrant minors (UMM). In 2020, our center incorporated urine-based nucleic acid amplification tests (NAAT)-based screening into the existing serology-based protocol (HIV, syphilis, hepatitis B/C), and we describe the additional diagnoses of STI identified through NAAT. We conducted a retrospective observational descriptive study (2020-2025) of 226 UMM (99.6% male) in Madrid undergoing serological screening for HIV, syphilis, hepatitis B and C, with additional urine-based multiplex PCR (NAAT) screening for STI. Urine-based NAAT, performed in 163/226 participants (72.1%), identified six positive cases (3.7%, 95% CI 1.4-7.8%) of C. trachomatis, M. genitalium, or Ureaplasma spp. Of these, four patients (2.5%, 95% CI 0.7-6.2%) had actionable infections that were treated. Serology identified no HIV (0/218) or hepatitis C cases (0/212), one syphilis case (0.5%, 95% CI 0.0-2.6%, 1/209), and three chronic hepatitis B cases (1.4%, 95% CI 0.3-3.9%, 3/221). None of the cases had symptoms recorded.

Urine NAAT identified six infections (four actionable) not detectable by serology. However, three of eight patients with actionable infections were lost to follow-up, highlighting that the benefit of systematic screening depends on strengthening linkage-to-care alongside testing.

• Serological screening (HIV, syphilis, hepatitis B/C) is standard in arrival health assessments for unaccompanied migrant minors, but systematic STI screening beyond serology is not routinely protocoled. • Systematic screening is especially valuable in this population, as follow-up is often limited by care fragmentation and transfers between reception centers.

• Urine-based NAAT screening identified additional STI in patients with no symptoms recorded, that were not detectable by serology alone.