by Gary Finnegan: HIV is easier than ever to prevent, detect and treat. Yet while life expectancy for people with the virus have improved over the past decade, the disease is proving difficult to stamp out and continues to spread in Europe.
The resurgent HIV epidemic among men who have sex with men (MSM) in the Netherlands is driven by several large, persistent, self-sustaining, and, in many cases, growing sub-epidemics shifting towards new generations of MSM, according to new research published in PLOS Medicine by the HIV Monitoring Foundation in Amsterdam, in collaboration with Imperial College London.
The researchers performed phylogenetic analysis, which uses genetic differences among viruses isolated from different individuals to derive patterns of HIV transmission, and mathematical modelling to determine whether the introduction of new strains or the spread of already circulating strains is responsible for the ongoing HIV epidemic occurring among MSM in the Netherlands.
The researchers took advantage of a large national observational HIV cohort, the ATHENA cohort, which includes anonymized data from HIV-infected patients followed longitudinally since 1996 in the 27 HIV treatment centers in the Netherlands. The study included 5,852 participants among whom the researchers were able to identify 106 large HIV transmission clusters. Ninety-one of which were primarily among MSM.
The researchers found that at least 54 (59%) of these 91 transmission clusters were already circulating before 1996, when combination antiretroviral therapy was introduced, and that they have persisted to the present. About a third of new HIV infections diagnosed among MSM since 1996 have involved viruses included in these long-lived clusters.
Although the average age at diagnosis for MSM within each of the clusters increased over the study period at a rate of 0.45 years/year, the average age at diagnosis was lower at initiation of new clusters and only increased by 0.28 years/ year.
“The analysis suggests that the epidemic amongst [MSM] is dispersed amongst a large number of self-sustaining or growing transmission clusters, many of which persisted throughout the 1990s, before increases in risk behaviour became widespread,” say the authors.
“Our study highlights that many different sub-epidemics have independently persisted for decades, despite the widespread availability of treatment, steadily increasing rates of diagnosis, and increasing tendency for early treatment initiation. The fastest growing sub-epidemics are the newest ones, which also tend to be amongst the youngest men.”