Three years ago, a few days before Christmas, the Food Safety News carried a news item stating that a Filipino-branded smoked mackerel wasn’t eviscerated in New York. As such, it may be likely that it could contain spores that cause botulism poisoning.
Under the law in New York, processed fish not eviscerated are prohibited because the spores of a Clostridium botulinum are more likely to be concentrated in the organs and entrails than any other portion of the fish, according to the report.
“Because the fish is uneviscerated, the product may contain with the spores of pathogenic bacteria, which can cause botulism, a serious and potentially fatal food borne illness,” the news item stated.
Clostridium botulinum, the bacterium that causes botulism, is commonly associated with bulging canned goods. The bulging, misshapen cans are due to an internal increase in pressure caused by the gas produced by the bacteria.
The toxins that the bacterium produce are really lethal. “These toxins are called neurotoxins because they damage nerves,” explains The Merck Manual of Medical Information. “Botulism toxins paralyze muscles by inhibiting the release of the neurotransmitter acetylcholine from nerves.”
The good news is that it is relatively rare. “It is an intoxication usually caused by ingestion of the botulism toxins formed in contaminated foods. Person to person transmission of botulism does not occur,” says the World Health Organization (WHO).
The bad news is the spores produced by the bacterium are everywhere and they are heat-resistant. “In the absence of oxygen, they germinate, grown and then excrete toxins,” the WHO says, adding that there are seven distinct forms but only four (types A, B, E and rarely F) cause human botulism. Types C, D and E cause illness in other mammals, birds and fish.
As they are neurotoxic, the toxins affect the nervous system. “Food-borne botulism is characterized by descending, flaccid paralysis that causes respiratory failure,” the Geneva-based United Nations health agency explains.
Early symptoms include marked fatigue, weakness and vertigo, usually followed by blurred vision, dry mouth and difficulty in swallowing and speaking. Vomiting, diarrhea, constipation and abdominal swelling may also occur.
“The disease can progress to weakness in the neck and arms, after which the respiratory muscles and muscles of the lower body are affected,” the WHO says. “There is no fever and no loss of consciousness.”
The above symptoms, however, are not caused by the bacterium itself, but by the toxin produced by the bacterium. Symptoms usually appear within 12 to 36 hours (within a minimum and maximum range of four to eight days) after exposure.
While incidence of botulism is low, the mortality rate is high “if prompt diagnosis and appropriate, immediate treatment [early administration of antitoxin and intensive respiratory care] are not given,” the WHO points out. “The disease can be fatal in 5 percent to 10 percent of cases.”
According to the WHO, the botulinum toxin can be found in variety of foods, including low-acid preserved vegetables, such as green beans, spinach, mushroom and beets; fish, including canned tuna, fermented, salted and smoked fish; and meat products, such as ham and sausage.
Aside from food-borne botulism, there are other types. Infant botulism, for instance, occurs mostly in infants under 6 months of age. This happens when infants ingest the spores which germinate into bacteria that colonize in the gut and release toxins. “In most adults and children older than about six months, this would not happen because natural defenses in intestines that develop over time prevent germination and growth of the bacterium,” the WHO says.
Although rare, wound botulism occurs when the spores get into an open wound and are able to reproduce in an anaerobic environment. This takes up to 2 weeks for the symptoms to appear and it has been associated with substance abuse. Drug addicts, take note!
Another rare type and which does not occur naturally is the inhalation botulism. This one is associated with accidental or intentional events (such as bioterrorism), which results in release of the toxins in aerosols.
“Following inhalation of the toxin, symptoms become visible between one to three days, with longer onset times for lower levels of intoxication,” the WHO says. To prevent further exposure to others, the patient’s clothing must be removed and stored in plastic bags until it can be washed thoroughly with soap and water. The patient is also required to take shower and be decontaminated immediately.
If there is food borne and airborne, there is also waterborne botulism. Theoretically, this type results from the ingestion of the pre-formed toxin, according to the WHO. “However, as common water treatment processes (such as boiling, disinfection with 0.1 percent hypochlorite bleach solution] destroy the toxin, the risk is considered low,” it says.
Meanwhile, adverse effects of the pure toxin have been reported as a result of its medical and/or cosmetic use in patients. The bacterium found in botulism is the same bacterium that is used to produce Botox, which makes women look 10 years younger.
The taming of the poisonous botulism toxin was made possible through biotechnology. “Without biotechnology, this toxin and probable biological weapon of mass destruction would have been a menace,” said a press release disseminated by Biolife News Service.
The biotechnologists who worked on botulinum reportedly took away the toxic genes, altered their makeup and eventually used the modified protein for treatment of various ailments.
Meanwhile, the WHO says food-borne botulism can be prevented if only people will follow good practice in food preparation, particularly during heating/sterilization and hygiene. The spores can be killed by very high temperature treatments such as commercial canning.
The WHO also recommends the five keys to safer food, which are: keep clean, separate raw and cooked, cook thoroughly, keep food at safe temperatures, and use safe water and raw materials.
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