Brotes De Hepatitis A Asociados Al Consumo De Arandanos

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An outbreak of hepatitis A associated with consumption of raw blueberries.
L Calder * G Simmons* C Thornley† P Taylor* K Pritchard* G Greening† J Bishop‡ Address for correspondence and reprints: Lester Calder Public Health Community Services Auckland District Health Board Private Bag 92 605 Symonds St AUCKLAND 1 Telephone: 64 9 623 4620 Fax: 64 9 630 7431 E-mail: lesterc@adhb.govt.nz. Wordcount: Text including tables, excluding title page, figure and references 2959 References 383 Running head: Blueberries and hepatitis A

* †

Public Health, Community Services, Auckland District Health Board Kenepuru Science Centre, Institute of Environmental Science & Research Limited ‡ Ministry of Health
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2Summary

The aim of this report is to describe the epidemiology, investigation and control of a hepatitis A (HAV) outbreak in New Zealand. Descriptive and analytical epidemiology, virology, product traceback and an orchard investigation were carried out. A case-control study involving 39 cases revealed that 56% of cases had consumed raw blueberries, as compared with 14% of controls (odds ratio7.6; 95% confidence intervals 2.6 – 22.4). Traceback of product through retailers and wholesalers implicated a single commercial orchard. DNA sequencing showed more than 90% similarity between HAV obtained from cases’ faeces and that found in product from the orchard. Sanitary audit of the orchard revealed multiple opportunities for contamination of product by pickers. This outbreak highlightsthe need for food safety programmes in the berry fruit industry.

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Introduction
The incidence of notified hepatitis A in New Zealand has declined in recent decades, from a rate of 145.7 per 100,000 population in 1971 1 to 1.6 in 2001 2. Overseas travel is currently the most common risk factor reported bynotified cases, followed by consumption of known or potentially contaminated food or water 2.

In the first three months of 2002 in Auckland, New Zealand, there was a sharp increase in the number of cases of hepatitis A notified to the public health office. An increase was also reported from other health districts in New Zealand. The aim of this report is to describe the epidemiology,investigation and control of this outbreak.

Methods

Epidemiologic investigation A case was defined as someone notified to a public health office in New Zealand with an acute illness with the following features: symptoms (including fever, malaise, anorexia, nausea or abdominal discomfort; jaundice or raised serum aminotransferase levels); and serum IgM antibodies against HAV (anti-HAV IgM). Unnotifiedcases were identified by obtaining positive anti-HAV IgM results from hospital and community laboratories. Cases reported between 1 January and 31 May 2002 were described in terms of time, place and person characteristics, and common risk factors for hepatitis A infection.

A hypothesis that blueberries were the source of illness was tested by a case-control study. Cases reported between 1 Januaryand 10 April 2002 were eligible for enrollment in the study.

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4 Controls were obtained for each case by telephoning sequentially the phone numbers on a randomly selected page of the telephone directory for the district in which their case resided. A new page was used for obtaining each control. It wasintended to obtain two controls for each case. Potential controls were excluded if they were under 16 years of age; had had hepatitis of any kind (because it was impractical to exclude only those with confirmed previous hepatitis A); had received hepatitis A vaccination; had received an injection of immunoglobulin in the past six months; did not speak English; or were unable to answer questions (e.g....