Does Your Patient Have a Foodborne Disease?

David W.K. Acheson, MD, FRCP


April 01, 2002

In This Article

Vomiting as the Major Presenting Symptom

Sudden onset of nausea and vomiting is usually caused by ingestion of a preformed toxin, such as S aureus enterotoxin, B cereus toxin, or a chemical irritant. Both toxins lead to vomiting as the primary symptom. In the case of S aureus toxin, symptoms usually begin 1-6 hours after ingestion, with nausea, vomiting, and abdominal cramps. Fever or diarrhea may occur in a minority of patients. S aureus toxin is heat-stable and often associated with consumption of prepared food, such as dairy products, produce, meats, eggs, and salads, that have been prepared by a food-handler.[4] Usually, the food-handler contaminates the product that, when keptat room temperature, allows multiplication of the organisms and subsequent production of toxins. Vomitus and food can be tested for the enterotoxin, but the diagnosis is usually clinical.

B cereus can also produce a heat-stable enterotoxin, which is typically found in starchy foods, such as rice.[5] The preformed B cereus enterotoxin causes rapid (within 1-6 hours) onset of nausea and profuse vomiting. The disease is usually self-limiting, although it has been very rarely associated with acute hepatic necrosis.[6] Diagnosis is usually clinical, although reference laboratories have the capability of testing food or vomitus for the toxin. Because these are preformed toxins, there is no risk of spread to others. However, identification of the contaminated food is important to prevent exposure to others.

Another group of foodborne diseases that typically causes vomiting as the predominant symptom are infections with Norwalk-like viruses. Norwalk-like viruses (also known as small, round, structured viruses) are now considered to be one of the most common causes of foodborne disease, and they typically manifest as nausea, vomiting, and watery diarrhea.[7] Norwalk-like viruses have been associated with large outbreaks on cruise ships, are readily transmitted from the vomitus of an infected person, and may be transmitted in aerosol form.[8] It is usually self-limiting, and no routine diagnostic assays are available. Reverse transcriptase polymerase chain reaction-based assays and electron microscopy can be used in reference settings. Shellfish are known to harbor Norwalk-like viruses, but otherwise these viruses are usually transmitted by food contaminated by a food-handler. Exposure to prepared food, such as salads, sandwiches, and fruit, are therefore risk factors.