Control of Foodborne Viruses at Retail - Retail Food Safety - page 64

2012 ; Richards 2012 ), a more comprehensive look at how these viruses spread by
water, food users, and handlers as well as animals, follows.
Water contamination : The introduction of sewage, manure, and other biosolids into
the watershed can contaminate water sources used in food production. Several stud-
ies have shown the capability of viruses to survive in sewage (Ehlers et al. 2005 ;
Kokkinos et al. 2011b ; Muniesa et al. 2009 ; Sattar and Westwood 1976 , 1977 , 1979 ;
Wei et al. 2010 ) even after treatment (Myrmel et al. 2006 ; van den Berg et al. 2005 ;
Villar et al. 2007 ) and the association with a risk for foodborne illness (Alcala et al.
2010 ; Ceballos et al. 2003 ; Ceylan et al. 2003 ; Cheong et al. 2009 ; Fiona Barker
et al. 2013 ; Kokkinos et al. 2011a ; Mathijs et al. 2012 ; Meng 2013 ; Steele and
Odumeru 2004 ; Tierney et al. 1977 ; Ueki et al. 2005 ). The incorporation of manage-
ment strategies to focus on the use of safe water has thus been identifi ed as a neces-
sary step in improving food safety (Godfree and Farrell 2005 ; Keraita et al. 2008 ;
Westrell et al. 2004 ). Yet in many areas of the world, maintaining a safe supply of
water can be diffi cult (Alcala et al. 2010 ; Ehlers et al. 2005 ; Kokkinos et al. 2011a ),
leaving regulatory offi cials facing a conundrum between the need for production
and the maintenance of safety.
Food workers and handlers : Food workers and handlers are an important part of
bringing foods to retail; however, these individuals also post a threat to the food,
particularly when they themselves are infected with a foodborne virus. One study
revealed that norovirus can reach as high as 10 10 virus particles per gram of fecal
matter (Atmar et al. 2008 ) while symptoms are being experienced. Lower levels can
be found even before symptoms have begun (Gaulin et al. 1999 ) and for several
weeks after symptoms have subsided (Gallimore et al. 2004 ). With the infectious
dose of this particular virus being less than 100 particles (Teunis et al. 2008 ), the
chance for contamination leading to infection is particularly high. Yet the most
likely chance for contamination in this case occurs at the foodhandling stage, which
is the last step before food products are provided to the consumer. As Michaels et al.
( 2004 ) and Mokhtari and Jaykus ( 2009 ) have both shown, food handlers represent
the most likely reservoir leading to high levels of viral contamination and subse-
quent infections to the consumer.
Zoonotic transmission : While the most recent concerns with zoonotic transmission
of pathogens such as avian infl uenza, SARS, and Nipah (Chmielewski and Swayne
2011 ; Guan et al. 2003 ; Smith et al. 2011 ) are due to close contact with live animals,
the impact of animals on the contamination of the food supply cannot be under-
stated. For example, the increase in HEV infections has been directly attributed to
the zoonotic potential of the virus from swine (Banks et al. 2010 ; Berto et al. 2012 ;
Bouwknegt et al. 2007 ; Casas et al. 2011 ; Di Bartolo et al. 2008 ; Fu et al. 2010 ;
Leblanc et al. 2010 ; Pavio et al. 2010 ; Scobie and Dalton 2013 ). The presence of the
virus not only in the liver of swine, but also their feces, suggests that this particular
virus could cause infection either through the traditional fecal-oral route or through
the bloodborne route during processing. In contrast, within the context of the viruses
identifi ed by the FAO/WHO, there is little evidence to demonstrate the likelihood of