The HIV Epidemic: High-Income Countries

Area of Science:

• Epidemiology
• Virology
• Public Health

Background:

• The human immunodeficiency virus (HIV) epidemic in higher-income nations is primarily driven by receptive anal intercourse, needle/syringe sharing among injection drug users, and vaginal intercourse.
• Alcohol and non-injecting drug use exacerbate sexual HIV vulnerability.
• Advances in diagnostic screening and antiretroviral therapy have significantly reduced blood-product transmissions and mother-to-child transmissions.

Purpose of the Study:

• To investigate the historical origins and transmission pathways of HIV strains in higher-income nations.
• To analyze the evolution of affected subgroups within the HIV epidemic.
• To apply phylodynamic methods for estimating epidemic parameters.

Main Methods:

• Molecular phylogenetic analysis of HIV strains.
• Phylodynamic approaches to estimate sequence evolution rates and network parameters.
• Analysis of epidemiological data on transmission routes and affected populations.

Main Results:

• Molecular phylogenetics confirms historical links between HIV strains from Central Africa to the US and Europe.
• HIV was introduced to Europe both directly from Africa and indirectly via the US, leading to distinct epidemics.
• Specific viral strains are associated with different risk groups and geographic regions, including injection drug use-related epidemics in Eastern Europe.
• Shifting demographics in affected populations, such as an increase in Black and minority ethnic men who have sex with men, were observed.

Conclusions:

• HIV transmission dynamics are complex, involving multiple introduction pathways and evolving risk group associations.
• Phylogenetic and phylodynamic analyses are crucial for understanding HIV epidemic origins, spread, and evolution.
• Continued surveillance and targeted interventions are necessary to address the evolving HIV epidemic.