Staphylococcal enterotoxin B (SEB) is a natural toxin produced by coagulase-positive Staphylococcus aureus. It produces one of the most common forms of food poisoning, a self-limited gastroenteritis, and under natural conditions it is usually ingested when improperly stored food is eaten. Person-to-person transmission of SEB does not occur; however, multiple patients may present that were exposed to the causative foods. SEB also causes nonmenstrual toxic shock syndrome.

SEB is classified as a Category B bioterrorism agent by the CDC. Category B agents are those that are moderately easy to disseminate, result in moderate morbidity rates and low mortality rates, and require specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance. It is relatively stable and easy to aerosolize. SEB was part of the US bioweapons program until it was destroyed in 1972. SEB is classified as a "superantigen."

The 3 main routes of exposure are ingestion, inhalation, and mucosal. Ingestion is the most common. The patient may appear with nausea and vomiting 1-8 hours after exposure along with diarrhea and cramping abdominal pain. No fever is seen with the foodborne illness, and there is no blood in the stool. Patients may present with tachycardia, hyperperistalsis, and hypotension, depending on the degree of dehydration. Children and the elderly may be more severely affected.

Diagnosis of inhalational exposure should prompt high suspicion of a bioterrorism event. Geographic distribution of the patients becomes important. There is usually an abrupt onset of fever (103°F-106°F [39°C-41°C]) beginning 3-12 hours after exposure that may continue for 3-5 days. Chills, headache, myalgias, and cough may continue for up to 4 weeks. Patients may complain of shortness of breath and chest pain. Large exposures may lead to pulmonary edema and ARDS. In an inhalational exposure, multiple patients of varying ages may present with similar symptoms within a short time frame.

Mucosal exposure is usually seen with BSL laboratory workers who inadvertently expose their conjunctiva or other mucosal surfaces. This will appear as conjunctivitis with some developing gastrointestinal symptoms as well.