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Hepatitis A and E viruses (HAV and HEV) potentially are transmitted by contaminated food or water. HAV and HEV belong to the families of Picornaviridae and Hepeviridae, respectively, and are nonenveloped viruses with a positive-sense, single-stranded RNA genome. HAV is highly resistant to environmental stresses. The most common risk factor for hepatitis A is personal contact with infected individuals. Foodborne hepatitis A cases in the United States have been caused by contaminated water, raw shellfish, fruits, vegetables, and ready-to-eat foods. HEV infection recently has been associated with the consumption of raw or undercooked meats.

There is a variety of methods available for the rapid detection and identification of viruses by electron microscopy as described in several reviews. The predominant techniques are classified as direct electron microscopy (DEM), immune electron microscopy (IEM), liquid phase immune electron microscopy (LPIEM) and solid phase immune electron microscopy (SPIEM). Each technique has inherent strengths and weaknesses. However, in recent years, the most progress for identifying viruses has been realized by the utilization of SPIEM.