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QUESTION: Ascaris eggs

p.darben at qut.edu.au p.darben at qut.edu.au
Wed Dec 13 19:39:25 EST 1995

On Fri, 8 Dec 1995, Sa'ad Al-Omari wrote:

> Can Ascaris lumbricoides eggs withstand boiling and remain viable?

Aha ! someone knows how to attract my attention. The simple answer is no, 
they can't. The major permeability barrier (with respect to water soluble 
materials) in Ascaris eggs is the internal lipid or ascaroside layer. The 
free ascarosides which make up this structure melt at around 80-90 C, so 
theoretically, if one can guarantee even distribution of heat throughout 
whatever it is you're boiling, the ascaroside layer is disrupted and the 
egg is freely permeable to water. Assuming the embryo also survives the 
heat treatment, it won't survive the resultant loss of water. Some 
interesting historical papers on the subject :

Ogata (1925) Ann. Trop. Med. Parasit. 19, 301-304
	- eggs killed within seconds at 60-70 C
Manalang (1927) Philip. J. Sci. 33, 249-257
	- significant drop in vitality after 5 minutes at 55 C
Anything by Fouquey, et al (eg. 1957) Bull. Soc. Chim. Biol. 39, 101-132
	- on the physical and chemical properties of the ascarosides
Tarr and Schnoes (1973) Arch. Biochem. Biophys. 158, 288-296
	- for a revised chemical structure


Peter Darben
School of Life Science
Queensland University of Technology,
Brisbane, Q4000,
"No longer making the world safe from pig worms - you're on your own now 

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