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.

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 the CDC's diagnostic capacity and enhanced disease surveillance. If used as a bioterrorism agent, SEB would most likely be dispersed as an aerosol producing an incapacitating but rarely lethal pulmonary and systemic syndrome. SEB was weaponized by the United States in the 1960s as an incapacitating agent. Via inhalation, the LD50* for SEB is approximately 0.02 µg/kg.

Whether acquired naturally or as a result of a bioterrorist attack, if SEB is ingested the symptoms include nausea, vomiting, diarrhea, and abdominal pain/cramps. If SEB is inhaled, it presents with sudden onset of high fever (39.5-41 degrees Celsius), myalgias, chills, non-productive cough, and headache. Conjunctivitis may also be noted. The fever may last 2-5 days and the cough may last for up to 4 weeks.

In a bioterrorist attack, inhalation of higher concentrations may result in more severe symptoms such as dyspnea, chest pain, pulmonary edema, and/or ARDS. The incubation period of ingested SEB is 4-10 hours; inhaled SEB is 3-20 hours.

*LD50 (LD = lethal dose) is the amount of a material, given all at once, that causes death in 50% of people.