Contamination of Foods by Food Handlers: Experiments on Hepatitis A Virus Transfer to Food and Its Interruption

Abstract

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/cm 2 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.Hepatitis A is a common form of acute viral hepatitis in many parts of the world. It is responsible for significant worldwide morbidity and occasional mortality (21, 27). Outbreaks of hepatitis A occur periodically throughout the world, and fecally contaminated food and water are the main vehicles (4). Although less than 10% of the cases of hepatitis A in the United States are associated with food-borne outbreaks (7), substantial costs are incurred by both society and the food industry as a result of these outbreaks (11). The foods implicated in these outbreaks include shellfish (13,14,18,22,28,31), sandwiches, dairy products, baked products, salads, fruits, and vegetables (9, 15). Examples of such outbreaks include the outbreak in Denver, Color., in 1992, in which more than 5,000 individuals were exposed to hepatitis A virus (HAV) due to consump...

Early infection and asymptomatic spread of hepatitis A virus in a public child care center in Rio de Janeiro, Brazil: should attending children under two years of age be vaccinated?

“…Nucleotide sequencing of a sample collected from that staff member revealed that the HAV genotype (subgenotype IA) was identical to that observed in the other 13 strains isolated in samples collected from individuals in the various classrooms, suggesting that this handler-food can have been a source of transmission (Figure). Previous studies have shown that HAV-excreting food handlers can contaminate the food they handle (Bidawid et al 2000, Fiore 2004). The second potential source of HAV infection is the children infected with subgenotypes IA and IB who attend the child care center but live in areas with poor sanitary conditions.…”

Scientific Opinion on an update on the present knowledge on the occurrence and control of foodborne viruses

“…In addition, transfer of HAV from artificially contaminated fingerpads of adult volunteers to pieces of fresh lettuce was observed by (Bidawid et al, 2000b). Touching the lettuce with artificially contaminated fingerpads for 10 s resulted in transfer of 9.2 % +/-0.9 % of the infectious virus.…”

“…Bidawid et al, (2000b) found that 3 kGy was needed in order to achieve 1 log reduction of HAV on lettuce or strawberries. Mallett et al, (1991) reported that 2.0 kGy was able to reduce HAV by 1 log in oysters and clams.…”

Scientific Opinion on the risk posed by pathogens in food of non‐animal origin. Part 2 (Salmonella and Norovirus in berries)

“…Viruses can be transferred from the hands onto food items or food preparation surfaces, particularly under moist conditions (Bidawid et al, 2000). It has been stated (EFSA Panel on Biological Hazards (BIOHAZ), 2011b; CAC, 2012) that persons with symptoms of gastroenteritis should be excluded from working in food production until the symptoms have subsided, e.g.…”