Viruses

Viruses are even smaller than bacteria. They consist of genetic material surrounded by a protein layer. Unlike bacteria, they can’t reproduce or multiply unless they are inside a living cell, but they can be carried on almost any surface and can survive for days or even months. Viruses are inactive or dormant until they enter a living cell. Then they use that cell to make more viruses and release them into the organism. The new viruses can then enter new cells and continue to multiply.

Because viruses do not multiply in food like bacteria, foodborne viral diseases are usually caused by contamination from people, food contact surfaces, or, in the case of seafood, contaminated water.