Staphylococcal Enterotoxin B
1:05 AM // 0 comments // sb blogger // Category: Biological Toxins , Staphylococcal Enterotoxin B , Weapons //Site of Action
The toxin acts by stimulating the immune system in a process very similar to that used by agents causing colds and other respiratory problems. This explains why it generates symptoms similar to a cough or cold. Technically, the toxin is a superantigen that causes an extremely strong response from the immune system, notably the release of cytokines. It is the release of cytokines that is responsible for most of the effects of the toxin.
Source
Food poisoning strains of Staphylococcus, especially S. aureus or S. pyogenes. About 40% of strains of S. aureusproduce at least some exotoxin. There are 10 known forms of Staphylococcal enterotoxin of which SEB is the most suitable for weapons use.
Symptoms, Treatment, Decontamination | |
Syndrome Name | Staphylococcal enterotoxin B poisoning |
Symptoms | A sudden onset of fever (39.5°C-41.1°C), chills, headache, myalgia, and nonproductive cough. Some patients may develop shortness of breath and retrosternal chest pain. Fever may last 2 to 5 days, and cough may persist for up to 4 weeks. Patients may also present with nausea, vomiting, and diarrhea if they swallow toxin. The effects on those exposed while under stress, such as soldiers in combat appear to be much more severe. Exposure can lead to vasodilation and a pathological drop in blood pressure, respiratory distress, shock and death within 40-60 h of exposure. Although SEB is not generally considered lethal, high levels of exposure can lead to septic shock and death. Toxicity can be potentiated by small levels of other Staphylococcal toxins. |
Onset of Symptoms | 3-12 hours after exposure to an aerosol. |
Rapid diagnostic assay | Precipitin tests. A rapid test known as a SMART Ticket is available to US armed forces. |
Supportive Care |
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Inactivation | Soap and water or 0.5% hypochlorite for 10-15 minutes. The toxin is heat stable. |
International Disease Classification Codes for Staphylococcal enterotoxin B Poisoning | ||
Disease | ICD-9-CM | ICD-10 |
Staphylococcal food poisoning | 005 | A05.0 |
Toxicity |
Staphylococcal enterotoxin B is not generally regarded as lethal. Orally, 25 micrograms of toxin induces vomiting in humans. However, it is much more toxic to people under stress, such as tired or wounded soldiers in the field. |
Chemical Properties | |
Structure | A protein of about 240 amino acids with a molecular weight of about 28,000 |
CA Name | Staphylococcal enterotoxin B |
Trivial Names |
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Registry Number | Sequences of the protein are registered at:
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Molecular Formula | Not applicable |
Molecular weight | Approx. 28,000 |
Solubility | Soluble in water |
pKa in water | |
Complete synthesis | Chemical synthesis is impractical. Toxin can be manufactured by fermentation of Staphylococcus aureus, which is relatively easy to culture, or a producer microorganism expressing the cloned gene for the toxin. |
Agent Properties
Staphylococcal enterotoxin B is a relatively robust protein that is easily aerosolized and that is stable in aerosol form. The producer organism is widespread and a common source of food poisoning that is relatively easy to culture. Although fairly rapidly disabling, the toxin has a very high lethal dose making it attractive to the military. However, stress and exhaustion can make the toxin much more lethal. 
Diagnosis of an attack is fairly difficult as there are no clear symptoms or tests for the toxin and it may be easily confused with the early stages of an attack with a live agent, such as anthrax or tularemia. Victims stabilize and begin to improve within a day or so rather than continuing to deteriorate. In essence, an attack can only be detected by watching it develop.
Tests by the United States in 1968 showed that an aerosol distributed from a single aircraft could cover an area about twice the size of metropolitan Los Angeles with about 30% of people in the area becoming casualties.
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