In recent years, a global increase in the number of reports of human vibriosis involving V. cholerae non-O1/O139 (NOVC) and other Vibrio spp. has been observed. In this context, the Belgian National Reference Center for Vibrio conducted an assessment of the presence of Vibrio spp. in recreational waters. Water sampling was performed monthly in different lakes in Wallonia and Flanders, including the North Sea. The collected water was then filtrated and cultured, and Vibrio spp. was quantified according to the Most Probable Number (MPN). Presumptive colonies were confirmed via MALDI-TOF, and PCR for virulence genes was applied if justified. No Vibrio spp. was found in the analyzed water bodies in Wallonia. However, NOVC was isolated from three different lakes in Flanders and from coastal water. In addition, V. alginolyticus and V. parahaemolyticus were also detected in coastal water. No clear impact of the pH and temperature was observed on Vibrio spp. occurrence. Our study demonstrates the presence of Vibrio spp. in different bathing water bodies, mostly in the north of Belgium, and supports the recommendation to include Vibrio spp. as a water quality indicator for bathing water quality assessment to ensure the safety of water recreational users in Belgium.

The international spread of HIV-1 sub-subtype A6 raises concerns due to its association with contraindications for long-acting injectable formulations of cabotegravir (LA-CAB) and rilpivirine (LA-RPV). This study investigated its increasing proportion in Belgium, assessing transmission dynamics and potential migration links. Additionally, genotypic drug resistance in the Belgian HIV-1 sub-subtype A6 population were analyzed and four automatic subtyping tools were compared. A dataset of 4764 HIV-1 protease and reverse transcriptase (RT) sequences from newly diagnosed, treatment-naïve individuals in Belgium (2013–2022) was analyzed. A combination of phylogenetic analysis and online subtyping tools identified 136 sub-subtype A6 sequences. The increase in the proportion of HIV-1 sub-subtype A6 observed in Belgium since 2020 reflects changing transmission patterns, especially among Belgium-born men having sex with men, and cannot be solely linked to the recent influx of Ukrainian migrants. Of these sub-subtype A6 sequences, less than 10% showed LA-CAB + LA-RPV resistance, mainly due to E138A within RT. HIVdb and ANRS reliably assessed resistance in this therapy-naïve cohort, and HIVdb, COMET, and SmartGene^® produced concordant subtyping results. While algorithm choice has little impact at low resistance prevalence, further research is necessary and HIVdb and ANRS remain more suitable for ongoing clinical and research use.

We report a case of confirmed virological failure on long-acting cabotegravir/rilpivirine (LA-CAB/RPV) in a patient with HIV-1 subtype B who met all eligibility criteria, maintained long-term viral suppression, and received all injections on schedule, with retrospective liquid chromatography-tandem mass spectrometry showing adequate plasma drug levels. Retrospective next-generation sequencing of proviral DNA revealed the non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance-associated mutation 188L in peripheral blood mononuclear cells 41 months prior to LA-CAB/RPV initiation, despite its absence in baseline plasma genotyping. This finding suggests that resistant variants may have been transmitted and archived from the start or selected during a brief NNRTI-based regimen. Mutational profiles differed across compartments, and the use of provirus-aware bioinformatic filters helped to down-weight resistance calls supported mainly by reads harboring frameshifts, stop codons or hypermutation-related APOBEC signatures within the sequenced regions, thus enhancing interpretability in a real-world clinical setting. This case illustrates how NGS, assisted by recent proviral sequence filtering tools, can be used to better select or offer individualized follow-up to individual undergoing injectable treatment. Trial registration PBMCs and gut-associated lymphoid tissue biopsies were prospectively collected from people living with HIV enrolled in two clinical studies conducted at the University Hospital of Liège, Belgium: the EDIT study (ClinicalTrials.gov identifier: NCT05351684) and the IDOLTIB study (ClinicalTrials.gov identifier NCT04034862)