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Viruses can be pathogenic to cells because they kill cells, cause a loss of special function of cells, or proliferate in the cell. All the damages that viruses cause take place at the cell level. During loss of special function, viral infection may induce the cells to relinquish their specialized functions. This can be a major problem if such cells have specialized activity and function in a vital organ. Proliferation at the expense of host cells can produce tumors or cancers in the host.
Food borne viruses are transmitted enterically, shed with feces, and infect by being ingested. Viruses can enter the food supply in several ways, such as infected food handlers or contamination by sewage. More than 100 known enteric viruses are excreted and find their way to sewage.
Foodborne Viruses and Human Diseases
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Virus
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Human Disease (Common Source)
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Hepatitis A
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Hepatitis A (shellfish, vegetables, milk)
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Hepatitis E
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Hepatitis E (indistinguishable from hepatitis A disease, water- borne, person to person)
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Norwalk-like
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Gastroenteritis (salads, raw oysters, clams)
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Rotavirus
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Gastroenteritis (transmitted by the fecal–oral route, person-to-person spread through contaminated hands)
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Caliciviruses
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Acute nonbacterial infectious gastroenteritis and viral gastroenteritis (fecal–oral routes via person-to-person contact or ingestion of contaminated foods and water)
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Astroviruses
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Viral gastroenteritis is usually a mild illness characterized by nausea, vomiting, diarrhea, malaise, abdominal pain, headache, and fever (fecal–oral routes via person-to-person contact or ingestion of contaminated foods and water)
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Preventive measures are the recommended means to avoid virus-induced food borne diseases. The virus cannot grow in food, but appears to be more stable in food than water. For example, in water at neutral pH, viruses are destroyed by temperatures above 85 0C but can survive pasteurization temperature in food.
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