From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.bio.food-science
Subject: Re: re Eggs and Salmonella
Date: Thu, 11 Sep 1997 13:50:10 +0100

In article <01bcbe3c$6bcc5640$142e5ba5@micro312.tamu.edu>, Alex Castillo
<castillo@tamu.edu> writes

>Bacterial growth increases the risk, yes; however I would not say that raw
>eggs are hazardous only when you allow for bacterial growth. This just
>makes them more hazardous. Even though low numbers of Salmonella in a food
>may not cause disease, many outbreaks have been reported where the
>infective dose was quite low.

We almost never actually know the infective dose. The relevent samples
have been consumed. We might know what bacterial load similar foods
nearby have, but this is not the same thing. We presume that it would be
the same, but the variability is likely to be very high.

>In addition, different host factors such as
>achlorhydria or an insufficient immune system may favour a Salmonella
>infection even with very low numbers of this pathogen.

Of course. However most of these outbreaks seem to happen in functions
where a lot of people have been fed. Having been to such functions I am
always struck by how often a buffet is spread out under hot lights in
heated rooms for extended periods before, and indeed whilst, it is being
consumed. Given an anisotopic bacterial loading (and things at very low
level often seem to be anisotopic) and a few hours to grow in an ideal
medium, the bacterial loading in random individual items may be rather
high.

I note that 20 years ago, when preservatives were usual, this was much
less of a problem.

--
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"