The Republic is not immune to a possible bioterrorist attack, the US Secretary for Health, Tommy Thompson, stressed in Dublin recently. He was launching a telemedicine initiative between the National Cancer Institute in the US and St Luke's Hospital, Dublin. There are half a dozen biological agents which are regarded as high priority, both in terms of their potential public health impact and their ease of dissemination and transmission. One of these is Clostridium Botulinum toxin, which causes a disease.
How many people availing of Botox injections realise the agent used to free them of wrinkles is exactly the same as a toxin which could feature in a bioterrorism attack? But the agent in cosmetic use is a much diluted and purified version of the botulinum toxin. Nevertheless, the neurotoxin used in Botox is one of four types of botulinum known to cause severe illness in humans. As such, it is of interest to terrorist organisations, such as al-Qaeda, who we are told are currently planning attacks against targets in the West.
Clostridium Botulinum is a bacteria which, unlike many other bugs, thrives in an oxygen-free environment. When it grows it produces a potent toxin that attacks the nervous system. This neurotoxin blocks the usual action of neurotransmitters, paralysing muscles throughout the body.
In the case of Botox, this effect is deliberately used to paralyse the facial muscles which make us frown, so temporarily getting rid of wrinkles and furrows. Symptoms in a full-blown case of botulism are very different and usually appear within 12-36 hours of exposure. The disease can be fatal in 5-10 per cent of cases.
The characteristic early symptoms and signs are marked fatigue, weakness and vertigo. These are followed by blurred vision, dry mouth and difficulty swallowing and speaking. If the toxin has been ingested then vomiting, diarrhoea and abdominal swelling may 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. Paralysis may make breathing difficult. If untreated, paralysis of the diaphragm and throat muscles can lead to death from respiratory failure.
Most naturally occurring cases of botulism happen when the organism is allowed to grow and produce toxin in food which is eaten without sufficient cooking to inactivate the toxin. This happens most often with lightly preserved foods such as fermented, salted or smoked fish and meat products. A preservative low in acid is another risk; Clostridium Botulinum will not grow in acidic foods. But the toxin is destroyed by normal cooking processes. However, from the terrorists' perspective, it is the possibility of introducing a neurotoxin into the water supply or releasing it into the atmosphere that makes it an attractive agent. Normal water treatment processes quickly inactivate the toxin, so the poisoning of public water supplies on a large scale is regarded as less likely than the possible release of airborne spores.
Laboratory workers have been accidentally exposed to inhalational botulism. In such cases, the neurological symptoms are similar to those seen in food-borne botulism, but the onset of symptoms may be quicker, possibly occurring less than one hour after exposure. On a positive note, person-to-person transmission does not occur.
Antibiotic treatment is not needed, but those affected must be admitted to hospital for the intravenous administration of anti-toxin. Some victims will require ongoing respiratory assistance in the form of mechanical ventilation, which may be required for weeks before independent breathing returns. One interesting "side-effect" from the widespread use of botulism toxin as a cosmetic agent is the reported improvement in symptoms reported by patients with chronic headache. In one study, 40 out of 100 patients who had a course of injections for wrinkles said they noticed complete relief from headaches. Doctors now think Botox may bring relief by relaxing tensed muscles.
Dr Houston can be contacted at mhouston@irish-times.ie. He regrets he cannot answer individual queries