Symptoms can occur between hours or weeks after eating contaminated food. Symptoms typically don’t develop for several days after eating contaminated food. Symptoms of viral or parasitic illnesses may not appear for several weeks after exposure. Symptoms usually last only a day or two, but in some cases can persist a week to 10 days. For most healthy people, foodborne illnesses are neither long-lasting nor life-threatening.
However, they can be severe in the very young, the very old, and people with certain diseases and conditions (immune disorders, including HIV infection, liver disease, diabetes, etc.)