C. botulinum causes the following forms of botulisms:(a) food-borne botulism, (b) infant botulism, and (c) wound botulism.
Food poisoning occurs on ingestion of preformed toxins in food contaminated with C. botulinum. The severity of illness varies from a mild to a very serious disease resulting in death within 24 hours. The incubation period is short, varies from 12 to 36 hours after ingestion of the contaminated food.
· Vomiting, nausea, dry mouth, constipation, abdominal pain, blurred vision with fixed dilated pupils are the initial signs. Fever, typically is absent.
· The disease progresses to as bilateral descending weakness of the peripheral muscles, leading to flaccid paralysis.
· Fever, typically is absent.
Death is due to respiratory paralysis and occurs in 1–7 days after onset of the disease. Case fatality varies from 10% to 25%. The use of intensive medical support facilities in the hospitals has reduced the fatality rate, which were as high as 20% seen earlier.
Infant botulism unlike food poisoning is caused by neurotox-ins produced in vivo by C. botulinum that have colonized the gastrointestinal tract of the infants. The initial symptoms are nonspecific and include constipation, lethargy, weakness, weak and altered cry, loss of head control, etc. The condition may progress to flaccid paralysis and respiratory arrest. The infants excrete toxins in their feces. The infant mortality due to infant botulism is relatively very low (11–20%).
Wound botulism occurs following heavy contamination of wounds with soil or water containing C. botulinum spores. The incubation period is 4–14 days with a mean of 10 days. Wound botulism is similar to food-borne botulism except that the incubation period is longer and no gastrointestinal symptoms are present. Often, the wound appears quite benign.