UPDATE: A key element of Fonterra's explanation of the botulism scare is being questioned by a Massey University professor.
“A dirty pipe would not be expected to harbour this organism. This is very unusual," associate Prof Steve Flint says.
In terms of preventing future contamination, the associate professor of food microbiology says, “This is a very unusual incident and until we know more about how this occurred, it is difficult to offer any advice.”
There have been two confirmed cases of botulism in New Zealand, Prof Flint says. "Both were associated with home preserved watercress and boiled mussels back in 1985."
EARLIER: A top academic has spoken out about the health threat posed by Clostridium botulinum found in Fonterra-produced whey, and possible reasons for the dairy cooperative's apparent delay in announcing its discovery.
"Apparently, the source of the bacteria has been traced to a dirty pipe in a processing factory. If this is true, it's a serious lapse in process control and obviously should not have occurred," John Brooks, Professor of Food Microbiology at AUT University says.
"The whey was made in May 2012 and it is unclear why the contamination has taken so long to come to light and why the company has been so slow to inform the government and the public. The company became aware of the contamination in March, but it was not until Wednesday 31st July 2013 that tests confirmed the presence of the bacteria.
"There are some possible explanations for the delay: third parties may have tested the product at some point in their own manufacturing operations and found it; the contamination levels may be very low, resulting in a requirement to test large amounts of product before the contaminants were found. Certainly, once the bacteria had been isolated, using modern methods,it should not have taken long to confirm the identification."
Real and justified threat
"It is not usual to test dairy products for the presence of Clostridium botulinum. When bacteria occur in a product at very low level and very infrequently, testing is ineffective in assuring safety and the cost is prohibitive. An Australian specification for whey protein concentrate does not mention Clostridia.
"The concern about the presence of C. botulinum is real and justified. The bacteria can produce a potent neurotoxin that causes paralysis and death. There have been only a couple of cases in New Zealand in the last 35 years. The toxin is released when the cells sporulate, so growth of the bacteria is necessary for toxin production. Bacteria cannot grow at the low water activity conditions in whey protein powder, but spores could germinate and grow if infant formula containing the contaminated whey protein were made up and then held warm for some period. The other very serious scenario is that infants fed the contaminated formula might then suffer botulism when the spores grow in the intestinal tract."
Hard to kill
Dr Siouxsie Wiles, HRC Hercus Fellow, School of Medical Sciences, University of Auckland, adds, "C. botulinum bacterium produces spores which are very hard to kill and thus help the bacterium survive adverse conditions.
"Botulism is caused by the ability of C. botulinum to produce several neurotoxins which prevent acetylcholine from being released from the motor nerve endings causing flaccid paralysis and symptoms of blurred vision, drooping eyelids, nausea, vomiting, diarrhea and/or constipation and cramps. In severe cases it leads to paralysis of the breathing muscles and causes respiratory failure.
"The toxins are produced when C. botulinum spores germinate and the bacterium starts to actively grow, which it can only do in an environment with no oxygen."
There are three main forms of illness caused by C. botulinum, the Dr Wiles says:
- Foodborne botulism, caused by consuming food or drink contaminated with botulinum toxins,
- Infant botulism, where the gastrointestinal tracts of babies becomes colonised by C. botulinumspores before their protective gut microbes establish are established. This is why parents are advised not to give honey to children under the age of 1,
- Wound botulism, when wounds become infected with C. botulinum spores.
Botulinum toxin A is one of the most toxic substances known to man, Dr Wiles says.
"One kilogram of it would be enough to kill the entire human population.
"[It's] Incredible then that this deadly toxin is voluntarily injected into the faces of millions in the pursuit of youth. They know it by its trade name - Botox. But it's not just used for treating wrinkles, botulinum toxin A is also used to treat spasms, migraines, squints, excessive blinking and excessive sweating."
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