How long until roundworms gone?

Here's a good article on gastrointestinal parasites of cats:
http://www.ivis.org/advances/Parasit...db_GI/ivis.pdf
It is a bit complex and overwhelming, but it contains a lot of information.

The time it takes from infection until there are adults in the gut producing eggs is 40-60 days. So all larvae that will wind up as adults in the gut should have finished their migration by that time, and from your perspective the cat would be "clear" of the parasite.

I figure you would want the full picture though, coaster, so here it is. Other larvae will encyst in the tissues and remain dormant for several years until they eventually die. These larvae never migrate to the gut however, so they are not a concern. These encysted larvae have no purpose in males or spayed females. In pregnant females, they migrate to the mammary glands and infect the kittens when they nurse.

The fact that Twinkie had a negative fecal in July does not preclude the notion that he has roundworms. If there are only a few worms in the system, it would be pretty difficult to find eggs on a fecal. Also, the fecal may have been done before the parasite had time to get to the gut and produce eggs.

Cats often pick up roundworm from eating mice, but they can also pick them up by ingesting soil contaminated with the eggs. So since the kitties go out on leashes, it is a realistic possibility that any of the three could have picked up a few roundworm eggs.

Heartgard should kill roundworm, several ectoparasites and act prophylactically against heartworm infection. So either your kitties were exposed one last time after the last heartgard application, or some of the little worms managed to escape unharmed.

I know this likely won't make you feel better, but having a low load of GI parasites can be beneficial. You know the whole business with kids that don't eat dirt or hang out around animals tend to develop allergies. Well, the cat's immune system has developed to exist compatibly with a small parasite burden. They are actually treating people with Crohn's disease with small doses of whipworm eggs. Strange but true!

Probably all of our pets have some sort of creepy-crawly on them right now. Did you know that a significant proportion of the human population carries Demodex in the glands in their eyelids? I guess my point is not to get too worried about the fact that a worm was found despite preventative treatment. By all means deworm the kitties, but don't let it get you too frazzled.

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