Legionnaires' Disease Associated in Potting Soils

[Paul Tyerman]

Duncan et al,

I cehcked into this about a year or two ago.  As far as I could find out at
that time, there has only been one known case that they are fairly certain
was due to Potting Mix..... the others were possibly from potting mix but
no evidence could be found to prove it.  At the time what Ii could
basically find out was that there was really very little substance to the
reports of the link between potting mix and legionnaire's disease.  At that
time there was no single case that could be conclusively linked the potting
mix!  Even those 3 links that were sent in the email implied that the cases
were thought to have come from the potting mix, but no tests had been done
to confirm the same strains etc, although they were more certain than most
information I could find at the time.

I'm sure there is legionella bacteria in a lot of damp areas, but that
doesn't mean that we automatically catch it by being in contact with it.
Because potting mix has a certain type in it, and we have that type does
not mean that it actually was passed to us by the potting mix, but rather
full testing need to be done to ascertain how close the strains were etc.
Sort of like any type of virus/common cold has different strains and are
constantly mutating...... they can be close to each other but not have
passed from one to the other because they are a different strain. I'm not
sure I am explaining this well.  Sorry.

Basically, you are far more likely to catch it in an old building who don't
clear out their airconditioning unit than you are from potting mix.
Basically in the very small event that there was legionella bacteria in
your potting mix bag you'd need to open the bag and inhale the first breath
to have any chance of getting it.  I take the precaution just for safety of
holding my breath whenever I open a potting mix bag, then facing away to
take my next breath.  I figure I'd rather be safe than sorry.  I suffer
from Chronic Fatigue and have a very poor imune system because of it, so if
there was ANY chance of catching it from potting mix then I would
definitely have done so (that sounds fatalistic, but given how my health
has been the last few years there are good reasons for me to say this <grin>).

I noticed that someone on this list said that they had it and they were
very ill.  I do not discount that they would be ill from legionnaires
disease, as it is DEFINITELY an aweful disease...... but did your case come
from potting mix, or was that just all you could work out it came from?  I
would be really interested to know, because if there have been definite
cases tracked and confirmed in potting mix then I'd love to hear more about
it.  It is something that has interested me, but I'm not a chemist or
virologist or anything like that <grin>.  I just use so much potting mix
myself that I would like to know for sure one way or the other.

Hopefully this is of interest to some of you reading it.

Cheers.

Paul Tyerman
Canberra, Australia

P.S.  Arisaema-wise they are pretty much all fully dormant here in very
early winter in Australia.... except a single Arisaema jacquemontii that
has decided that after our VERY strange summer and autumn drought and water
restrictions etc it is now going to shoot.  The flower should open within
the next few days and will certainly be the first one I have EVER had
flower at this time of year before.  It'll be flowering at the same time as
so many of you in the Northern Hemisphere will have it in flower as well!!
Cool eh?