· All the cases of botulism reported in the literature are due to accidental poisoning. Though botulinum toxin could possibly serve as a potent homicidal poison, its use for nefarious purposes has fortunately been non-existent so far. Most cases of foodborne botulism result from eating improperly preserved home-canned foods, and are virtually confined to Western countries, even though some incidents have recently been reported from Iran, Russia, Japan, and even India.
· Contrary to popular opinion, outbreaks of botulism are generally not associated with multiple cases per occurrence. However, there have been some reports of mass poisoning.
· An international outbreak of botulism food poisoning in 1989 was traced back to whitefish contaminated by C. botulinum type E sold in a New York delicatessen. Five people were hospitalised, one of whom died. Laboratory confirmation was obtained in 3 of the cases. All cases, which occurred in the US and Israel, were traced to the consumption of ribbetz, a freshwater whitefish soaked in brine, dried, and preserved by refrigeration.
· Only 2% of foodborne botulism outbreaks are due to canned foods originating from the commercial food processing industry, while 4% are associated with food purchased in restaurants, and the remaining (more than 90%) cases result from faulty home-canning. Vegetables with or without meat, are the causative agents in about 70%, meat in 17%, and fish in 13% of cases. Although home-made canned foods remain the major sources of botulism outbreaks, of late there has been an increase in commercially prepared products causing botulism outbreaks. Due to recent inno- vations in methods of preserving food products by using vacuum-packed and refrigerated or heat-treated foods at an inadequate temperature, the development of neurotoxino- genic Clostridium has increased in both the US and Europe.
· Types A, B, and E are the common strains involved in botu- lism outbreaks. The case fatality ratio for type A is abou 12%, while for types B and E, it is approximately 10%. A few cases have recently been reported to have been caused by other Clostridium species—Cl. baratii and Cl. butyricum.
· Although most cases of botulism recover completely, espe- cially when prompt treatment is administered, a few may be associated with long-term sequelae such as dysgeusia, dry mouth, constipation, dyspepsia, arthralgia, exertional dyspnoea, and easy fatiguability.
· Recently, a fourth type of botulism (apart from foodborne, wound, and infant types) was identified by the Centers for Disease Control in the USA, which affects patients older than 1 year in whom no particular food source can be implicated. This has come to be called “Infant type adult botulism”. Risk factors for this type include recent antibiotic therapy, gastric achlorhydria, and previous intestinal surgery.
· Botulinum toxin is today finding an important place in therapeutics, being used for the treatment of a number of neurological and ophthalmological disorders. It is also said to be useful in controlling hyperhydrosis. Botulinum toxin Type A (BTA) has been used to treat blepharospasm, stra- bismus, cervical dystonia, and moderate to severe glabellar lines. Some of the side effects reported with its use have included the following: headache, ptosis, dysphagia, upper respiratory tract infection, flu-like syndrome, and nausea.
Diplopia, ectropion, and lower eyelid droop have been less commonly reported.
· Of late, botulinum toxin misuse as a bioterrorism agent is gaining notoriety. The toxin can be easily delivered by aerosol, or used to contaminate food or water supplies. If inhaled, the toxin produces clinical symptoms that are similar to foodborne intoxication; however, time to onset may be delayed. The toxin is relatively easy to produce, and is highly lethal in small quantities. In recent history, countries and/or terrorist organisations (e.g. Iraq during thePersian Gulf War and the Aum Shrinrikyo in Tokyo) havebeen known to produce botulinum toxin as part of their offensive weapons programme.