Organisms that cause food poisoning

Different organisms cause illness in different ways. Some multiply in the gut, while others produce toxins before or after food is eaten. Viruses can spread through contaminated hands, surfaces, food or water. Parasites may be acquired from contaminated food or drink. The symptoms overlap: diarrhoea, abdominal cramps, nausea, vomiting and fever can all occur. The type of organism cannot usually be identified from symptoms alone, and the meal that caused illness may not be obvious. A clinician may use the illness pattern, exposure history and, when appropriate, a stool test to guide care.

Take regular sips of water or oral rehydration solution and rest. Eat small amounts when appetite returns. Wash hands with soap and water after using the toilet and before handling food; avoid preparing meals for other people while you have diarrhoea. Do not start leftover antibiotics or anti-parasitic medicine without medical advice, because the correct treatment depends on the organism and some illnesses need only fluids and rest. Record the onset, stool changes, fever, travel, shared meals and medicines.

Seek urgent care for blood in stool, severe or worsening pain, confusion, fainting, very little urine, or inability to drink. Prompt assessment is also needed for high fever with severe weakness. Contact a clinician earlier for pregnancy, infancy, older age or a weakened immune system. Continuing symptoms after travel or after others from the same meal become ill may require testing and public-health advice.

Could testing identify the organism causing my illness? Do I need specific treatment, or is oral rehydration enough? How long should I avoid preparing food for other people?