Hepatitis A Associated with Green Onions
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《新英格兰医药杂志》
To the Editor: The report by Wheeler et al. (Sept. 1 issue)1on an outbreak of hepatitis A arouses concern because of the number of people infected from a single contaminated food and because of the severity of the disease, reflected in the rates of hospitalization (26 percent) and fulminant hepatitis (0.7 percent). All 13 of the restaurant employees with a positive test for the IgM antibody to the hepatitis A virus had symptomatic hepatitis, whereas none had mild or asymptomatic infection. As stated in the accompanying editorial by Di Giammarino and Dienstag,2 the older age of people with the infection in developed countries, as compared with those in developing countries, may explain this severity. But this outbreak also involved 28 children 12 years of age and younger (12 percent), and 37 children (28 percent) were included in the control group. Since most children infected with the hepatitis A virus remain asymptomatic,3 it would have been interesting to know the hepatitis A virus serologic status of the control subjects. In fact, an absence of anti–hepatitis A virus antibodies among the control subjects, excluding asymptomatic infections, would confirm the uncommon virulence of this outbreak, whereas even a low prevalence of immunity to hepatitis A virus would reduce the number of exposed but uninfected subjects, thus increasing the odds ratio for onion consumption in patients as compared with controls.
Laura Milazzo, M.D.
L. Sacco Hospital
20157 Milan, Italy
laura.milazzo@virgilio.it
References
Wheeler C, Vogt TM, Armstrong GL, et al. An outbreak of hepatitis A associated with green onions. N Engl J Med 2005;353:890-897.
Di Giammarino L, Dienstag JL. Hepatitis A -- the price of progress. N Engl J Med 2005;353:944-946.
Cuthbert JA. Hepatitis A: old and new. Clin Microbiol Rev 2001;14:38-58.
To the Editor: Is there any solution for epidemics of hepatitis A associated with contaminated green onions besides universal hepatitis A virus vaccination? High hydrostatic-pressure processing can inactivate the hepatitis A virus without damaging the flavor of raw vegetables,1 but the related costs may be high. Alternatively, although the hepatitis A virus cannot multiply in foods, it persists because of its adsorption capacity on the surface of some fresh vegetables (lettuce, raspberries, green onions, etc.).2 Thus, washing or chlorination does not guarantee a reduction in viral contamination; adsorption protects so efficiently that even refrigeration does not affect the survival of several types of virus in green onions.3 Hence, instead of cleaning the green onions by rinsing them with plain water, the restaurant employees should give them another washing and another peeling of the outer layer (the first one having been removed during harvesting) — a time-consuming process. After that, the green onions can be slowly washed in chlorinated water and then rinsed with plain water, at which point they are ready for consumption.
Salvador Vale, M.D.
Indesalud
24010 Campeche, Mexico
svalemayorga@yahoo.com.mx
References
Calci KR, Meade GK, Tezloff RC, Kingsley DH. High-pressure inactivation of hepatitis A virus within oysters. Appl Environ Microbiol 2005;71:339-343.
Croci L, De Medici D, Scalfaro C, Fiore A, Toti L. The survival of hepatitis A virus in fresh produce. Int J Food Microbiol 2002;73:29-34.
Kurdziel AS, Wilkinson N, Langton S, Cook N. Survival of poliovirus on soft fruit and salad vegetables. J Food Prot 2001;64:706-709.
Laura Milazzo, M.D.
L. Sacco Hospital
20157 Milan, Italy
laura.milazzo@virgilio.it
References
Wheeler C, Vogt TM, Armstrong GL, et al. An outbreak of hepatitis A associated with green onions. N Engl J Med 2005;353:890-897.
Di Giammarino L, Dienstag JL. Hepatitis A -- the price of progress. N Engl J Med 2005;353:944-946.
Cuthbert JA. Hepatitis A: old and new. Clin Microbiol Rev 2001;14:38-58.
To the Editor: Is there any solution for epidemics of hepatitis A associated with contaminated green onions besides universal hepatitis A virus vaccination? High hydrostatic-pressure processing can inactivate the hepatitis A virus without damaging the flavor of raw vegetables,1 but the related costs may be high. Alternatively, although the hepatitis A virus cannot multiply in foods, it persists because of its adsorption capacity on the surface of some fresh vegetables (lettuce, raspberries, green onions, etc.).2 Thus, washing or chlorination does not guarantee a reduction in viral contamination; adsorption protects so efficiently that even refrigeration does not affect the survival of several types of virus in green onions.3 Hence, instead of cleaning the green onions by rinsing them with plain water, the restaurant employees should give them another washing and another peeling of the outer layer (the first one having been removed during harvesting) — a time-consuming process. After that, the green onions can be slowly washed in chlorinated water and then rinsed with plain water, at which point they are ready for consumption.
Salvador Vale, M.D.
Indesalud
24010 Campeche, Mexico
svalemayorga@yahoo.com.mx
References
Calci KR, Meade GK, Tezloff RC, Kingsley DH. High-pressure inactivation of hepatitis A virus within oysters. Appl Environ Microbiol 2005;71:339-343.
Croci L, De Medici D, Scalfaro C, Fiore A, Toti L. The survival of hepatitis A virus in fresh produce. Int J Food Microbiol 2002;73:29-34.
Kurdziel AS, Wilkinson N, Langton S, Cook N. Survival of poliovirus on soft fruit and salad vegetables. J Food Prot 2001;64:706-709.