PLoS ONE (Jan 2012)

Factors associated to duration of hepatitis a outbreaks: implications for control.

  • Nuria Torner,
  • Sonia Broner,
  • Ana Martinez,
  • Cecilia Tortajada,
  • Patricia Garcia de Olalla,
  • Irene Barrabeig,
  • MariaRosa Sala,
  • Neus Camps,
  • Sofia Minguell,
  • Josep Alvarez,
  • Gloria Ferrús,
  • Roser Torra,
  • Pere Godoy,
  • Angela Dominguez,
  • Hepatitis A Surveillance Group of Catalonia, Spain

DOI
https://doi.org/10.1371/journal.pone.0031339
Journal volume & issue
Vol. 7, no. 2
p. e31339

Abstract

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Even though hepatitis A mass vaccination effectiveness is high, outbreaks continue to occur. The aim of this study was to investigate the association between duration and characteristics of hepatitis A outbreaks. Hepatitis A (HA) outbreaks reported between 1991 and 2007 were studied. An outbreak was defined as ≥2 epidemiologically-linked cases with ≥1 case laboratory-confirmed by detection of HA immunoglobulin M (IgM) antibodies. Relationships between explanatory variables and outbreak duration were assessed by logistic regression. During the study period, 268 outbreaks (rate 2.45 per million persons-year) and 1396 cases (rate 1.28 per 10(5) persons-year) were reported. Factors associated with shorter duration were time to intervention (OR = 0.96; 95% CI: 0.94-0.98) and school setting (OR = 0.39; 95% CI: 0.16-0.92). In person-to-person transmission outbreaks only time to intervention was associated with shorter outbreak duration (OR = 0.96; 95% CI: 0.95-0.98). The only variables associated with shorter outbreak duration were early administration of IG or vaccine and a school setting. Timely reporting HA outbreaks was associated with outbreak duration. Making confirmed HA infections statutory reportable for clinical laboratories could diminish outbreak duration.