Cryptosporidium (Cryptosporidium parvum), are not viruses, but a parasitic protozoan and are much larger then bacteria. Here is a good web site for more information. Pete

http://vm.cfsan.fda.gov/~mow/chap24.html

Yeah... and there's anecdotal evidence that oocysts will settle out in still water - apparently they are denser than water. So maybe one could greatly reduce the number of oocysts ingested in emergency situations simply by letting water sit for a few hours and then carefully decanting off the upper region of water?

You wouldn't happen to have some lying around the lab that you could confirm my theory with, would you, Pete? Giardia or Crypto or both?

As we've discussed previously, it requires a certain quantity of ingested oocysts to cause problems - a few / several won't bother most folks at all. And some folks seem to be unaffected by fairly large numbers - huge variability in folks vulnerability...

The problem is protozoans cannot be cultured as they are obligate intracellular parasites. We do receive mice that are infected with Giardia and/or Entomebia and/or other protozoans and we are able visualize their non-cystic state with a phase-contrast microscope from intestinal/cecal contents. However, we do not stain for the cysts, nor do we collect them for any additional studies.

It would be logical to believe the cysts would eventually sink to the bottom, as it is likely their density is greater than water. However, it might not take much movement to re-suspend them. I would not rely totally upon that method.

Pete

We have an electrically operated RO system in our RV. We are able to provide power with our solar array as well as run all of our other needed electrical stuff. The process is slow, but it provides for our needs.

The system is one of the under sink models purchased from Sams Club. The brine is fed back into the supply tank. This method has worked for years and we have the membrane checked abour once a year. Had to replace the membrane once after several years because of damage done to it during handling. It was still functioning well.

RO is nice in the southwestern US as there are many dissolved salts in the water. Now I hate to drink anything else.

For an interesting article on living with Giardia, see
http://www.getlostmagazine.com/mcbee/2004/0404giardia/giardia.html

And several of the sites I have visited on Giardia & Crypto indicate that trouble can be caused by as little as one cyst. You can be treated multiple times, and still might have the cysts lying dormant, waiting for a nice, stressful period in your life to flare up again.

YUCK!

Sue

Sue,

Sounds like fun... but seriously, the "one cyst" is kind of like the golden BB that brings down an aircraft - it can happen, but... plenty of evidence that a measurable portion of the population is highly resistent and the "average" person (if there is such an animal) has to ingest some larger number - 30? 50? - whatever - before getting sick. Or maybe it's "don't drink the water in Months with an "R" " or...

Good thing we're variable like that or one bug would wipe out the species next week... wait, was was that about only 2 varieties of wheat grown now...

I don't worry about it, in any event.

Tom