Question from a student 20150505

Q:

I am a student of FNSC3180 this semester. I would like to ask 2 questions about final exam materials.

1/ what are the differences of Kuru’s disease, CJD and vCJD ? 

2/ In B9 of Paper 2012, part B, why shouldn’t we use data in pH 4.0 condition to calculate? The reason why I think like this is that the question stated that the food with actual pH 4.5 was reported wrongly as pH 4.0 . It also said “ some of the batch of pig knuckles was canned already, using the canning process designed for pickled pig knuckles of pH4.0” Therefore, when it comes to the part B to calculate the no. of D in the PROBLEMATIC canning process for these target organism, I was thinking of using data from pH 4.0 condition.

A:

1. All three have the same symptoms of spongiform encephalopathy.

Major differences:

Kuru's disease: Onset times vary, source of prion identified to be the tissues of dead relatives consumed by the patients

CJD: Onset among old people, average 68 years

vCJD: Onset among young people, median 28 years old

there are also other characteristics differentiating the two but we do not need to go into the details here.

2. When the food is heated, the real D value working is always the one linked to the food's condition. No matter how we set the heating protocols for whatever condition we target, what is ACTUALLY working is linked to the characteristic of the food. So when the food is actually pH 4.5, The D value to use is the one at pH4.5.