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Applied and Environmental Microbiology, July 2000, p. 2759-2763, Vol. 66, No. 7
Health Canada, Food Directorate, Bureau of
Microbial Hazards, Ottawa, Ontario, Canada K1A
0L2,1 and Department of
Biochemistry, Microbiology and Immunology, Faculty of Medicine,
University of Ottawa, Ottawa, Ontario, Canada2
Received 16 November 1999/Accepted 10 April 2000
Hepatitis A virus (HAV) is an important pathogen which has been
responsible for many food-borne outbreaks. HAV-excreting food handlers,
especially those with poor hygienic practices, can contaminate the
foods which they handle. Consumption of such foods without further
processing has been known to result in cases of infectious hepatitis.
Since quantitative data on virus transfer during contact of hands with
foods is not available, we investigated the transfer of HAV from
artificially contaminated fingerpads of adult volunteers to pieces of
fresh lettuce. Touching the lettuce with artificially contaminated
fingerpads for 10 s at a pressure of 0.2 to 0.4 kg/cm2
resulted in transfer of 9.2% ± 0.9% of the infectious virus. The
pretreatments tested to interrupt virus transfer from contaminated fingerpads included (i) hard-water rinsing and towel drying, (ii) application of a domestic or commercial topical agent followed by water
rinsing and towel drying, and (iii) exposure to a hand gel containing
62% ethanol or 75% liquid ethanol without water rinsing or towel
drying. When the fingerpads were treated with the topical agents or
alcohol before the lettuce was touched, the amount of infectious virus
transferred to lettuce was reduced from 9.2% to between 0.3 and 0.6%
(depending on the topical agent used), which was a reduction in virus
transfer of up to 30-fold. Surprisingly, no virus transfer to lettuce
was detected when the fingerpads were rinsed with water alone before
the lettuce was touched. However, additional experiments with water
rinsing in which smaller volumes of water were used (1 ml instead of 15 ml) showed that the rate of virus transfer to lettuce was 0.3% ± 0.1%. The variability in virus transfer rates following water rinsing may indicate that the volume of water at least in part influences virus
removal from the fingerpads differently, a possibility which should be
investigated further. This study provided novel information concerning
the rate of virus transfer to foods and a model for investigating the
transfer of viral and other food-borne pathogens from contaminated
hands to foods, as well as techniques for interrupting such transfer to
improve food safety.
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Contamination of Foods by Food Handlers:
Experiments on Hepatitis A Virus Transfer to Food and Its
Interruption
*
Corresponding author. Mailing address: Health Canada,
Food Directorate, Bureau of Microbial Hazards, Sir F.G. Banting
Research Centre, Ross Ave., Tunney's Pasture, Postal locator no.
2204A2, Ottawa, Ontario, Canada K1A 0L2. Phone: (613) 957-0908. Fax:
(613) 941-0280. E-mail: Sabah_Bidawid{at}hc-sc.gc.ca.
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