In article , says...

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?


http://www.patient.co.uk/doctor/Fasciola-Hepatica.htm

quote

" Life cycle

Immature eggs are discharged in the biliary ducts and in the stool. The eggs release
miracidia, which invade a suitable snail intermediate host.
In the snail the parasites develop into cercariae, which are released from the snail and
encyst as metacercariae on aquatic vegetation or other surfaces.
Mammals become infected by eating contaminated vegetation. Humans become infected by
ingesting contaminated freshwater plants, especially watercress.
After ingestion, the metacercariae encyst in the duodenum and migrate through the
intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts,
where they develop into adults. The adult flukes live in the large biliary ducts of the
mammalian host.
Human infection by consumption of raw liver from infected sheep, goats, and cows has also
been reported."

Liverfluke in farm livestock is on the increase in UK.

In UK it should only be grown in potable water ( drinking standard, not, untreated
river/garden water). If someone unwell is planning to consume a serious quantity of raw cress
for health reasons, it might be unwise to increase the risk of other zoonotic health problems
such as e coli and campylobacter.

AIUI zoonoses are not the only risk to human health from eating raw watercress .New Zealand
(where maori eat a LOT of cress) is currently concerned about the levels of bacteria, metals
and pesticides being taken up by watercress, in the land-runoff that enters rivers.

http://www.ncbi.nlm.nih.gov/pubmed/15108742


Janet.