Botulism

Botulism is an acute toxic disease caused by ingestion of food containing Clostridium botulinum exotoxin. It was first discovered in 1793 in Wildbad, southern Germany, after people became ill from eating spoiled sausages; the name derives from botulus, Latin for sausage. Four clinical types are now recognized: foodborne botulism, infant botulism, wound botulism, and inhalational botulism. All present mainly with neurological symptoms and have a high case fatality rate.

Common Symptoms

Weakness; sore throat; eye muscle paralysis; diplopia; ptosis; fatigue; dizziness; nausea; loss of light reflex; vertigo

Causes and Pathogenesis

(1) Etiology: Clostridium botulinum was first isolated by van Ermengem in 1897 during a food poisoning outbreak in Belgium. The organism is 2 to 4 μm long and 0.5 to 2 μm wide, with 4 to 8 flagella, motile, non-encapsulated, growing anaerobically and readily forming spores. Young cells are Gram-positive; older spore-forming cells are Gram-negative. The bacterium is widely distributed in nature as spores in soil, vegetables, fruits, and grains, and in animal feces. Spores are highly heat-resistant, remaining active after 6 h of boiling; autoclaving at 120°C requires 20 min to kill, dry heat at 180°C requires 5 to 15 min. It is not sensitive to common disinfectants; 5% phenol or 20% formalin takes 24 h, and 10% hydrochloric acid takes 1 h to kill. Botulinum toxin is an exotoxin secreted by C. botulinum, essentially a polypeptide. Based on antigenicity, it is classified into 8 types: A, B, C (Ca, Cb), D, E, F, and G. Types A, B, and E mainly cause human disease; types F and G are occasionally reported; types C and D mainly cause disease in wild waterfowl, cattle, horses, ducks, chickens, and minks. Among known chemical and biological toxins, botulinum toxin is extremely potent; the lethal dose for humans is about 2 μg. It is a neurotoxin with the highest affinity for neural tissue for type A, followed by E, then B. The toxin resists gastric acid but is heat-sensitive, destroyed by 30 min at 80°C or 10 min at 100°C. Under dry, sealed, dark, room-temperature conditions, toxin can persist for years; toxin in canned foods contaminated by C. botulinum can remain toxic for a long time. The toxin and its formalin-treated toxoid are antigenic; inoculated animals produce antitoxic serum that neutralizes homologous toxin. (2) Pathogenesis: Human ingestion of food contaminated with C. botulinum exotoxin is not destroyed by gastric acid or digestive enzymes. Botulinum toxin exists intracellularly as a non-toxic precursor, activated by its own activating enzyme; intestinal trypsin also has activating effect. After being broken down into smaller molecules by proteolytic enzymes in the stomach and small intestine, the exotoxin is absorbed into the bloodstream, reaching motor nerve synapses and cholinergic nerve endings. Its action has two stages: first, the toxin reversibly binds to the nerve terminal surface and can be neutralized by corresponding antitoxin; second, at the acetylcholine release site, it irreversibly binds to adjacent receptors, inhibiting release of the neurotransmitter acetylcholine, preventing muscle contraction and causing sustained paralysis of eye muscles, pharyngeal muscles, and skeletal muscles. Pathological changes are nonspecific and do not necessarily reflect severity; the more severe the poisoning, the faster the death and the milder the tissue changes. Autopsy occasionally shows degeneration of cranial nerve nuclei and anterior horn cells, meningeal congestion and edema, and congestion and small thrombi in the liver, spleen, kidney, and other organs. Infant botulism occurs in infants under 6 months; the mechanism differs: no toxin is detected in the food ingested, but C. botulinum and its toxin are found in the stool, suggesting that ingestion of spores or vegetative cells (which contain no exotoxin) leads to intestinal proliferation and exotoxin production, absorbed through the intestinal mucosa to cause symptoms.

Treatment

Drug therapy, supportive therapy

Preventive Measures

Professional guidance: 1. Strictly enforce food management laws; conduct hygiene inspections of canned foods, hams, and cured meats. Salted fish, bacon, and sausages must be thoroughly steamed, boiled, or fried before eating. Fermented or spoiled foods are prohibited. Canned foods with bulging lids or signs of deterioration must not be sold. 2. Do not eat spoiled or deteriorated food. 3. If co-diners develop botulism, asymptomatic individuals may be given 1000 to 2000 U of polyvalent serum prophylactically and observed. Those who must frequently eat canned food may receive prophylactic C. botulinum toxoid, 1 ml subcutaneously once weekly for 3 doses. 4. In wartime, the enemy may disseminate botulinum toxin aerosol or contaminate water sources with crystalline toxin; necessary personnel should receive active immunization.

Department to Visit

It is recommended to visit the Emergency department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.