North American Fruit Explorers mailing list at ibiblio

[Lucky Pittman <lucky.pittman@murraystate.edu>]

At 12:22 PM 7/23/2004 -0400, Doc L wrote:
> I thought it acted to plug up the insects' respiratory spiracles.  I've
> heard it works on intestinal worms as a vermifuge by penetrating their
> tender little bodies.  Some of the "Earth Children" may have used it for
> this purpose. Under the microscope it looks like what it is; remains of
> diatoms, some with sharp spicules but most are tiny siliceous particles.

Doc & all,
I have to deal with this almost  on a daily basis - especially with the 
upsurgence of goat production in this area, and the immense problem 
gastrointestinal parasites (Haemonchus contortus, in particular) pose to 
sheep & goats in this area.  I'm constantly encountering folks who've been 
snookered in by the DE snake-oil salesmen touting it as a 'safe, 'natural', 
or 'organic' means of parasite control.
Lots of information on DE out there on the Internet, but if you'll look - 
not even with a jaundiced eye - you'll see that all the 'success stories' 
are merely anecdotal tales - no controlled comparisons between DE-treated 
animals/untreated controls/anthelminthic-treated animals; and to add to 
that confusion, even in the few quasi-scientific comparisons that have been 
done, there's been no determination as to whether they were using an 
anthelminthic preparation that the resident population of nematode 
parasites had already become totally resistant to.

On the surface, the DE theory sounds plausible - you've got these tiny 
little diatom skeletons with razor-sharp edges that lacerate the nematodes' 
cuticle, causing them to dessicate and die.
However, on further examination, that fails because:
1) These 'worms' are living in a fluid environment - either in the lumen of 
the gut, or, in some instances, in intestinal crypts or encysted in the 
submucosa - so, even if they happened to receive a 'laceration', they're 
not going to dessicate.
2) Since these worms are in a liquid environment, I've got serious doubts 
about any diatom fragments causing 'lacerations' - yeah, if you put some 
worms between two boards, sprinkled 'em with DE, and rubbed the boards back 
& forth against one another, it would probably do the trick, but in a fluid 
medium, I'd expect the DE particles to just float along, causing no damage.
If they're so damaging to the chitinous cuticle of an intestinal parasite, 
why wouldn't they cut the epithelial lining of the intestinal tract of the 
animal to shreds?
3)I'm not so sure but that the 'food grade' DE that's recommended for this 
use has been milled to such a fine consistency that any spicules/sharp 
edges are no longer present in effective configurations.

I have seen documented incidences in which 'outbreaks' of urolithiasis 
(urinary stones) have occurred in feedlot steers & lambs when DE was 
incorporated into their ration as a 'dewormer'.  It's high in minerals, and 
in those cases, it skewed the Calcium:Phosphorus ratio in the ration so far 
out of whack that stones precipitated, causing urethral blockages.
I'd be inclined to bet that any 'improvement' in condition noted in the 
testimonials could probably be attributed more to improved 
mineral/micronutrient supply, provided by the DE, than to any effect it 
might have on intestinal parasites.

And, finally, on the vast majority of webpages touting the greatness of DE 
- you'll see that they're usually ready and willing to sell you some, for a 
healthy sum.

Lucky