Contamination of foods by food handlers: Experiments on hepatitis A virus transfer to food and its interruption

Hepatitis A virus (HAV) is an important pathogen which has been responsible for many food-borne outbreaks, HAV-excreting food handlers, especially tho se with poor hygienic practices, can contaminate the foods which they handl e. Consumption of such foods without further processing has been known to r esult in cases of infectious hepatitis. Since quantitative data on virus tr ansfer during contact of hands with foods is not available, we investigated the transfer of HAV from artificially contaminated fingerpads of adult vol unteers 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/cm(2) resul ted 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 c ommercial topical agent followed by water rinsing and towel drying, and (ii i) exposure to a hand gel containing 62% ethanol or 75% liquid ethanol with out water rinsing or towel drying. When the fingerpads were treated with th e topical agents or alcohol before the lettuce was touched, the amount of i nfectious 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 v irus transfer of up to 30-fold. Surprisingly, no virus transfer to lettuce was detected when the fingerpads were rinsed with water alone before the le ttuce was touched, However, additional experiments with water rinsing in wh ich 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 diff erently, a possibility which should be investigated further. This study pro vided novel information concerning the rate of virus transfer to foods and a model for investigating the transfer of viral and other food-borne pathog ens from contaminated hands to foods, as well as techniques for interruptin g such transfer to improve food safety.