Botulism is food poisoning caused by the exotoxin (neurotoxin) that is secreted by Clostridium botulinum.
Etiology and pathogenesis
Clostridium botulinum is a gram-positive, anaerobic, sporogeneric bacillus that creates exotoxin resistant to heat (cooking for at least 10 minutes destroys it). Exotoxin inhibits the release of acetylcholine at nerve endings, thus causing weakness and easy fatigue of striated and smooth muscles. Clostridium is located in the soil, it is a saprophyte that produces spores in natural surroundings, whereas under anaerobic conditions (canned foods) it may multiply and produce exotoxin. The production of toxins is possible at temperatures of 3 degrees C, even when conditions are not strictly anaerobic (low oxygen concentration). Of the seven types of exotoxin (A, B , C , D , E , F and G), four have effects on man (A, B , E and F). The most common poisonings are exotoxins A and B, while type E mainly associated with seafood poisoning. Poisonings by type F exotoxin are rare but possible.
Clinical presentation
Symptoms of the disease can occur 12-36 hours (several hours to 8 days) after ingestion of contaminated food; one third of patients will have the symptoms indicating acute alimentary intoxication (nausea , vomiting and diarrhea), while others will immediately experience muscular weakness, rapid fatigue, pronounced dryness of mucous membranes of the mouth, constipation followed by bulbmotor symptoms (double vision, inhibition of the reaction of the pupil to light, ptosis, etc.). Swallowing and speech are weakened, tendon reflexes are preserved, consciousness also. Neurological symptoms usually afflict both sides of the body, they are symmetrical and weakness is spread from head muscles downwards. The disease can be fatal due to it affecting respiratory muscles or aspiration pneumonia due to paralysis of the muscles of the pharynx.
There is no fever, and the pulse rate is within normal range unless concomitant infection with other pathogens occurs.
Exotoxin of Clostridium can enter the body through wounds in the skin when the wound is infected by spores of Clostridium botulinum.
With botulism in infants, child’s intestine was colonized by spores of Clostridium. This is an infection in the true sense of the word as opposed to intoxication in adults.
Diagnosis and differential diagnosis
Diagnosis is based on clinical presentation, and is established by the discovery of toxins in the blood (neutralization in mice) or proof of Clostridium in the guinea pig food. Electromyography may help in some cases.
By differential diagnosis, botulism can be confused with Guillain-Barré syndrome, poliomyelitis, myasthenia gravis, etc.
Prognosis
The prognosis is different depending on the epidemic, lethality is 16-65%, death usually occurs from 4 to 8 days of illness.
Treatment
The treatment comprises of administration of a trivalent serum (antitoxin A, B, E) iv. Starting dose for adults is 500 to 750 ml/day and is repeated the next day if they demonstrate again the toxin in the blood. The serum has a greater prophylactic value in people who ate the same food but are not yet ill. In addition to giving the serum, the stomach should be pumped, given laxatives and enema in order to prevent further absorption of the toxin.
Prophylaxis
Proper preservation of both commercial and domestic products is an essential step in preventing disease. Infants should not be given honey because it may contain spores of Clostridium. Active immunization to toxoid (vaccination) is applicable only in persons who are in professional contact with Clostridium or its toxins.