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Origin of HAV strains responsible for 2016-2017 outbreak among MSM: Viral phylodynamics in Lazio region

Claudia Minosse1, Francesco Messina1, Anna Rosa Garbuglia1

  • 1National Institute for Infectious Diseases "Lazzaro Spallanzani" I.R.C.C.S., Rome, Italy.

Plos One
|May 30, 2020
PubMed

Insights

Hepatitis A virus (HAV) outbreaks in Europe are linked to specific risk groups, including Men-Who-Have-Sex-With-Men (MSM). This study analyzed HAV sequences in Lazio, Italy, revealing a significant viral expansion and outbreak in 2016-2017, consistent with European MSM-specific epidemics.

Area of Science:

  • * Virology
  • * Epidemiology
  • * Molecular Biology

Background:

  • * Hepatitis A virus (HAV) infections in Europe are often associated with specific risk groups and foodborne transmission.
  • * Sexual transmission of HAV is a significant factor, particularly among Men-Who-Have-Sex-With-Men (MSM), leading to MSM-specific outbreaks in Europe.
  • * Understanding the genetic diversity and transmission dynamics of HAV is crucial for public health interventions.

Purpose of the Study:

  • * To conduct a molecular epidemiologic and phylodynamic analysis of HAV sequences in Lazio, central Italy.
  • * To identify the genetic background and phylogenetic relationships of HAV strains during a large outbreak.
  • * To model HAV infection dynamics and assess the epidemic's scale and continuity with European MSM-specific outbreaks.

Main Methods:

  • * Analysis of HAV sequences collected in Lazio between 2013 and 2018.
  • * Molecular epidemiology to assess genetic diversity and identify viral clusters (VRD_521_2016 and RIVM-HAV16-090).
  • * Phylodynamic modeling to estimate viral population expansion times and effective reproduction number (Re) during the 2016-2017 outbreak.

Main Results:

  • * Low genetic diversity of HAV was observed in Lazio during 2016-2017, with high frequencies of VRD_521_2016 and RIVM-HAV16-090 strains, indicating a significant viral population expansion event.
  • * The initial expansion of these HAV clusters was dated back to 2012.
  • * The effective reproduction number (Re) peaked at 1.73 in mid-2016, correlating with the incidence of acute hepatitis A (AHA) cases in the region, confirming a substantial outbreak.

Conclusions:

  • * The study highlights the magnitude of the HAV outbreak in Lazio during 2016-2017.
  • * Findings demonstrate the epidemic's continuity with ongoing MSM-specific HAV outbreaks in Europe.
  • * The HAV dataset is available on the Nextstrain platform for real-time monitoring of future outbreaks.

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