Enhanced HIV-1 surveillance using molecular epidemiology to study and monitor HIV-1 outbreaks among intravenous drug users (IDUs) in Athens and Bucharest

- This enhanced molecular surveillance study revealed important characteristics of two epidemics in Athens and Bucharest.
- The timely discovery of an outbreak and the investigation of its molecular characteristics can provide valuable information, at a very early stage.
- The implementation of phylodynamic models allows estimating of effective reproductive number over time, which is crucial for outbreak investigation.
- Information about the time of origin and emergence in chronic indolent infections (HIV, HCV and HBV) may provide further insights for successful interventions.

BackgroundA significant increase in HIV-1 diagnoses was reported among Injecting Drug Users (IDUs) in the Athens (17-fold) and Bucharest (9-fold) metropolitan areas starting 2011.MethodsMolecular analyses were conducted on HIV-1 sequences from IDUs comprising 51% and 20% of the diagnosed cases among IDUs during 2011-2013 for Greece and Romania, respectively. Phylodynamic analyses were performed using the newly developed birth-death serial skyline model which allows estimating of important epidemiological parameters, as implemented in BEAST programme.ResultsMost infections (>90%) occurred within four and three IDU local transmission networks in Athens and Bucharest, respectively. For all Romanian clusters, the viral strains originated from local circulating strains, whereas in Athens, the local strains seeded only two of the four sub-outbreaks. Birth-death skyline plots suggest a more explosive nature for sub-outbreaks in Bucharest than in Athens. In Athens, two sub-outbreaks had been controlled (Re < 1.0) by 2013 and two appeared to be endemic (Re ∼ 1). In Bucharest one outbreak continued to expand (Re > 1.0) and two had been controlled (Re < 1.0). The lead times were shorter for the outbreak in Athens than in Bucharest.ConclusionsEnhanced molecular surveillance proved useful to gain information about the origin, causal pathways, dispersal patterns and transmission dynamics of the outbreaks that can be useful in a public health setting.