Work

HIV epidemic and needs beyond fast-track cities: a transmission network analysis to study the dynamics of HIV clusters in a French region near Paris

Year: 2026

Type: article

Abstract: ABSTRACT The Centre-Loire Valley region is a low-density demographic and medical region near the fast-track city of Paris, with persistent elevated rates of positive HIV testing. We investigated the role and characteristics of transmission clusters in the HIV dynamics in this region for appropriate local response. HIV pol gene sequences collected in Centre-Loire Valley over a decade (2010–2020) were included in a phylogenetic analysis combined with epidemiological data. Putative transmission clusters were inferred using HIV Transmission Cluster Engine methods. Risk factors of being part of a cluster were studied using multivariate logistic regression models. Of the 1,305 participants, 579 (44%) were born in France, mainly from sub-Saharan Africa; 494 (38%) were women; 433 (33%) were men who have sex with men (MSM); and 694 (53%) were heterosexuals. Migrants had lower CD4 cell count at diagnosis than those born in France (296 vs 443, P < 0.01), likely due to delayed time to diagnosis. A total of 86 clusters were identified (clustering rate of 21%), including 33 of size ≥3 involving 170 participants (3–16 per cluster). MSM (OR 2.16, P < 0.01) and higher viral load (OR 1.21, P < 0.01) were risk factors of clustering. Individuals born abroad were clearly not detected in clusters, contrary to those born in France (OR 0.03, P < 0.01). Among large clusters, persistent virological control was achieved in a median of 75% of participants vs 83% outside clusters ( P < 0.01). Molecular epidemiology showed that MSM were part of local transmission networks but not heterosexual migrants, suggesting distinct epidemic features and needs. IMPORTANCE To end the HIV epidemic, it will also be necessary to halt the spread of the virus beyond large metropolitan areas, where resources are more limited and epidemiological trends are more difficult to grasp. In this study, we showed how molecular epidemiology could be used at the regional level to inform HIV surveillance and support decision-making for an appropriate local response. This could be especially helpful when national databases are lacking. We investigated the role and characteristics of transmission clusters in the HIV dynamics of the Centre-Loire Valley region, a low-density demographic and medical region near Paris, with a focus on migrants. We found that men who have sex with men (MSM) were part of local transmission clusters but not heterosexual migrants, suggesting distinct HIV epidemics and needs. Epidemic control would require further implementation of pre-exposure prophylaxis and treatment as prevention for MSM to slow the dynamics of HIV clusters locally, and generalized access to HIV screening for migrants.

Source: Microbiology Spectrum

DOI: 10.1128/spectrum.02542-25