Hepatitis A and Human Norovirus
Dr. Gibson introduced and gave an overview of the two most relevant enteric viruses in food safety—human Norovirus and Hepatitis A—on which Dr. Jaykus later elaborated. The viruses share several characteristics, such as being resistant to environmental degradation, having a low infectious dose, and shedding from infected individuals at high concentrations. The enteric viruses are also highly persistent on foods and are difficult to inactivate. According to Dr. Jaykus, the viruses can persist on surfaces for days to weeks at room temperature; on foods in water, the viruses can persist for weeks to months if refrigerated, and indefinitely if frozen. Although viral persistence is strong for enteric viruses, the viruses’ survivability depends on the surface, matrix, and temperatures to which they are subject.
Hepatitis A is more common in low-income countries and its common modes of transmission are ready-to-eat (RTE) foods, fresh and frozen produce, and LMFs. Hepatitis A has a public health impact of over 37,000 foodborne cases in the U.S., annually. Norovirus, which causes approximately 5.5 million cases of foodborne illness in the U.S. each year, is mainly transmitted through foods at restaurants due to contamination by infected food handlers; soft, red fruits are also associated with Norovirus due to being hand-harvested. Foods that are handled by humans during harvesting, processing, or preparation are common vehicles for Norovirus as the pathogen can remain infectious and shed from infected individuals for up to eight weeks.
In dry environments, the enteric viruses can transfer between surfaces at a rate of 5–10 percent; in moist environments, the viruses’ rate of transferability increases to over 95 percent. Hepatitis A and Norovirus have also shown to be effective at attaching and sticking to existing biofilms.