On 23/09/2012 17:12, Chris Hogg wrote:
On Sun, 23 Sep 2012 16:36:01 +0100, Farmer Giles
wrote:

On 23/09/2012 16:04, Chris Hogg wrote:
On Sun, 23 Sep 2012 14:11:23 +0100, Farmer Giles
wrote:

I'm thinking of growing a serious quantity of watercress in my garden.

We have a small river running at the bottom of it that I plan to
utilise. I don't actually mean growing it in the river, because I'm
concerned about liver fluke infestation as it flows through sheep
pasture a short way upstream, but using the water from it.

The thing is that, despite a lot of searching, I'm not sure how liver
fluke is transmitted via watercress - ie is it taken up by the plants or
do the flukes somehow attach themselves to it? If it is the latter,
would some kind of filtering remove them?

Anyone here know about this?

Don't think much of your searching ability!

Probably on a par with your politeness and tact.


Lots of info out there if
you google for watercress liver-fluke uk. See for example
www.torrens.org.uk/FFF/Fluke.html and many more.

Yes, I have found lots of information about the fluke, but none of it is
very clear about how the parasite passes from the plant to the person
who eats it - ie does one have to eat the flukes themselves, or their
eggs, or is it transmitted in other ways? Also, as I asked, can they be
removed by filtering?

From my first link:

"The adult fluke lays its eggs which pass out in the hosts faeces and
hatch into a larval form (miracidia) which, if the faeces are
deposited in water, swim around and infect water snails (mainly
lymnaea truncatula but probably other species as well). Having
infected the snail, the larva develops until it is ready for the next
stage of its life when it develops into multiple cercaria which leave
the snail host and attach themselves to plants growing in the water
such as grass or watercress, where they encyst.

The life cycle is completed when the grass (or other plant material)
is eaten. The encysted cercariae come to life in the gut, migrate
through the gut wall and travel to the liver where the adult fluke
develops."

What more do you want?

Oh dear, how many times do I have to say that I don't intend to grow it
*in* the water! I wanted to know (but please don't 'trouble' yourself to
attempt another 'reply'!) that can whatever it is that transmits the
parasite be filtered out.




I also read that it's illegal to grow watercress commercially in river
water, and that the water has to be of drinking quality; see
http://www.thewatercresscompany.co.uk/docs/Media_17.pdf.


I wasn't talking about growing it *in* river water - as I made quite
clear - but about using river water to grow it. It is perfectly legal to
abstract a fairly large quantity of water from streams and rivers for
horticultural purposes. As for it having to be of drinking quality, that
sounds like nonsense. What is 'drinking quality' - does that include
rainwater collected in a butt? If so, then I wouldn't like to drink it!

There are legal standards for the quality of drinking water. Google
for drinking water standards uk.


There may be, but most sources of water in which watercress is grown
commercially would not meet them.

Anyway, and leaving that side, why do some people respond to questions
on usenet as if the questioner has knocked on their door at 2.00am
demanding immediate assistance? If you don't know the answer, or find
the question too stupid for words, why bother to attempt a reply?

I've been posting on usenet for many years, but recently I've stopped
posting to all newsgroups - except this one, and I'll do that when I've
finished writing this bit - because they all seemed to have become
populated either with nutters or with those who appear to be in a
permanent bad mood.

Cheerio.