From http://www.straightdope.com/columns/010119.html:
Isn’t it both? I guess he meant to say “worm” instead of parasite.
(post edited to fix link)
[Edited by Arnold Winkelried on 01-20-2001 at 06:34 PM]
I believe you are correct. Ringworm is a parasitic fungus, so that the final word should be “worm,” not “parasite.” Perhaps Cecil or his minions should edit the column? 
Incidentally, I got a “404: not found” error when I clicked on The Ryan’s link. The one above worked in “Preview.”
There needs to be a space on both sides of the URL for the link to work. The Ryan has a colon immediately after “html”.
A parasite, by definition, is an organism which makes its living off of a creature of a different species, to the detriment of that creature.
This is why fetuses are not parasites 
Yeah, Cecil meant worms.
Methinks “Morbid Curiosity” mistook “ringworm” for “roundworm”. Intestinal roundworms (i.e. usually ascarid nematodes) can be fairly large and fairly mobile, but I doubt they could go all the way up to the nose, because of the tight closure of the oesophagus-gastric junction (the cardia), even under anesthesia. As a veterinarian, I can tell you that many animals with roundworm infections get operated upon, and I’ve never heard of worms popping out of an animal’s nares.
Are roundworms the ones which, at some point in the life cycle, enter the throat and are then swallowed? I was pondering over that possibility.
Parasite
From Webster’s Revised Unabridged Dictionary (1913) [web1913]:
…
(Bot.)
(a) A plant obtaining nourishment immediately from other plants to which it attaches itself, and whose juices
it absorbs; – sometimes, but erroneously, called epiphyte.
(b) A plant living on or within an animal, and supported at its expense, as many species of fungi of the genus {Torrubia}.
(Zo["o]l.)
(a) An animal which lives during the whole or part of its existence on or in the body of some other animal, feeding upon its food, blood, or tissues, as lice, tapeworms, etc.
(b) An animal which steals the food of another, as the parasitic jager.
(c) An animal which habitually uses the nest of another, as the cowbird and the European cuckoo.
I don’t see where the host has to be an organism of another species. Hence, a fetus and/or embryo is also a parasite.
I got that definition from a parasitologist. If you want to ignore the species issue, a fetus/mother interaction would be +/0, which makes it commensalism, not parasitism. Which is another reason a fetus is not a parasite
barbitu8, I followed your link, entered “parasite”, and got the following:
Since the fetus contributes to the survival of the parent (in the sense of perpetuating the genes) it’s not a parasite.
It’s funny that I got a different definition, but mine was obviously old, being from a 1913 dictionary. Anyway, the fetus does not contribute to the survival of the parent, but to the species. The parent can do just fine w/o it. We’re just quibbling over definitions, anyway. No one, other than me, looks upon a fetus or embryo as a parasite.
You, and my mom.
No. That was after you were born.
Have you been talking to her?
Fixed. The Boss said, “I don’t care what I SAID, you know what I MEANT.”
This Boss character–he giving you a hard time? You want we should lean on him a little? Don’t say anything–just cough twice–we’ll take it from there. No permanent marks, either.