HIV Transmission Patterns Among Immigrant Latinos Illuminated by the Integration of Phylogenetic and Migration Data

Abstract

Latinos represent a growing proportion of HIV cases in North Carolina (NC). Understanding how immigrants are involved in local HIV transmission is important to guide interventions. We used phylogenetics to characterize Latino involvement in local HIV transmission chains. Transmission clusters were identified from maximum-likelihood phylogenies constructed with HIV pol sequences from 177 Latinos and 1,496 non-Latinos receiving care in NC. Highly supported clusters involving one or more Latinos were characterized. Migration data were obtained from interviews and chart review. Factors associated with cluster membership were identified using log-binomial regression. Most Latinos were male (76%), immigrants (83%), and had HIV-1B (99%). Immigrants were more likely to report heterosexual risk (67% vs. 23%) than U.S.-born Latinos (p < 0.01). We identified 32 clusters that included one or more Latinos; these involved 53 Latinos (30%) and 41 non-Latinos. Immigrant and U.S.-born Latinos were equally likely to be in clusters, but immigrants were more likely to be in clusters with another Latino (78% vs. 29%; p = 0.02). Cluster composition by ethnicity and risk behavior varied by cluster size; larger clusters contained fewer immigrants and more men who have sex with men (MSM). Factors associated with immigrant membership in local transmission clusters included age <30 years [RR 2.34 (95% CI 1.47-3.73)], Mexican origin [RR 2.55 (95% CI 1.29-6.88)], and residing in the United States longer before diagnosis [RR 1.53 (95% CI 1.09-2.15), per 10 years]. While some Latinos immigrate with HIV infection, many immigrants are involved in transmission networks after arrival, particularly MSM. HIV testing and prevention interventions must consider this heterogeneity and may be better targeted by integrating phylogenetic analyses.

FIG. 1.

Maximum-likelihood phylogenetic tree showing the HIV transmission clusters (n = 32) involving ≥1 Latino sequences from initial tree built with sequences from 177 Latinos and 1496 non-Latinos (only clusters involving Latino sequences with bootstrap support >90% and supported by confirmatory analyses are shown here). Nodes defining clusters are labeled with bootstrap support generated by RAxML. Larger clusters (n ≥ 3 members) are labeled C1–C10. Small cluster “pairs” (n = 2 members) that are heterosexual (HET) are labeled P1–P12 and men who have sex with men (MSM) are labeled P13–P22). Sequences with transmitted drug resistance (TDR) are labeled with identified mutations. *Cluster pairs (n = 5) involving partners immigrating from the same country and where partnerships began prior to immigration. Clusters involving women (n = 14) are highlighted in gray.