Hepatitis A outbreak in Italy, 2013: a matched case–control study

C Montaño-Remacha; L Ricotta; V Alfonsi; A Bella; M E Tosti; A R Ciccaglione; R Bruni; S Taffon; M Equestre; M N Losio; V Carraro; S Franchini; B Natter; M Augschiller; A Foppa; C Gualanduzzi; E Massimiliani; A C Finarelli; B M Borrini; T Gallo; V Cozza; M Chironna; R Prato; C Rizzo; Collective Central Task Force on Hepatitis

doi:10.2807/1560-7917.ES2014.19.37.20906

Surveillance and outbreak reports Open Access

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Hepatitis A outbreak in Italy, 2013: a matched case–control study
C Montaño-Remacha^1,2 , L Ricotta^1,3 , V Alfonsi¹ , A Bella¹ , M E Tosti¹ , A R Ciccaglione¹ , R Bruni¹ , S Taffon¹ , M Equestre¹ , M N Losio⁴ , V Carraro⁵ , S Franchini⁵ , B Natter⁶ , M Augschiller⁶ , A Foppa⁶ , C Gualanduzzi⁷ , E Massimiliani⁷ , A C Finarelli⁷ , B M Borrini⁷ , T Gallo⁸ , V Cozza^2,9 , M Chironna¹⁰ , R Prato⁹ , C Rizzo¹ , Collective Central Task Force on Hepatitis¹¹
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Affiliations: ¹ Istituto Superiore di Sanità (ISS), Rome, Italy ² European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, Stockholm, Sweden ³ Dept. of Biomedical and Neuromotor Sciences, University of Bologna, Italy ⁴ Institute Experimental Zooprophylactic of Lombardy and Emilia Romagna, Italy ⁵ Prevention Dept., Province of Trento, Italy ⁶ Prevention Dept., Province of Bolzano, Italy ⁷ Public Health Service - Directorate General for Health and Social Policy - Emilia-Romagna Region, Italy ⁸ Prevention Dept. - ASS4 Medio Friuli, Udine, Italy ⁹ Dept. of Medical and Surgical Sciences, University of Foggia, Italy ¹⁰ Dept. of Biomedical Sciences and Human Oncology, University of Bari, Italy ¹¹ The members of the Central Task Force on Hepatitis A are listed at the end of the article

Correspondence:
C Montaño-Remacha
cmontanno gmail.com
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Citation style for this article: Montaño-Remacha C, Ricotta L, Alfonsi V, Bella A, Tosti M E, Ciccaglione A R, Bruni R, Taffon S, Equestre M, Losio M N, Carraro V, Franchini S, Natter B, Augschiller M, Foppa A, Gualanduzzi C, Massimiliani E, Finarelli A C, Borrini B M, Gallo T, Cozza V, Chironna M, Prato R, Rizzo C, Central Task Force on Hepatitis Collective. Hepatitis A outbreak in Italy, 2013: a matched case–control study. Euro Surveill. 2014;19(37):pii=20906. https://doi.org/10.2807/1560-7917.ES2014.19.37.20906 Received: 30 Oct 2013

Abstract

Between January and May 2013 a hepatitis A (HA) incidence increase was detected in Italy, signalling an outbreak. A retrospective matched case-control study was conducted to identify the source of infection. A case was defined as a resident of any of five regions (Apulia, autonomous province of Bolzano, Emilia-Romagna, Friuli-Venezia-Giulia and autonomous province of Trento), who had symptom onset between 1 January and 31 May2013 as well a positive test for anti-HA virus IgM. We compared each case with four age-and neighbourhood-matched controls. Overall 119 cases and 419 controls were enrolled. Berries were found as the main risk factor for HA (adjusted odds ratio (ORadj): 4.2; 95% confidence interval (CI): 2.5-7.0) followed by raw seafood (ORadj: 3.8; 95% CI: 2.2-6.8; PAF: 26%). Sequencing the virion protein (VP)1-2a region from 24 cases yielded a common sequence (GenBank number: KF182323). The same sequence was amplified from frozen mixed berries consumed by some cases as well as from isolates from Dutch and German HA patients, who had visited some of the affected Italian provinces during the outbreak. These findings suggested berries as the main source of the Italian outbreak. Control measures included voluntary recall of the confirmed frozen mixed berry batches and a trace-back investigation was initiated. The Ministry of Health website recommends frozen berries to be cooked for two minutes before eating. .