What Now :
Female roundworms lay eggs inside your cat's gut, and your cat passes them in the feces. It may take up to several weeks or a month for them to become infective. Once they develop into the infective larva stage, they can remain infective for years.

Preventing Infection :
Deworming females prior to pregnancy would make sense, except that medications do not affect dormant worms that reactivate during pregnancy, just in time to infect the kittens.

Containing the worm population requires containing your cat and keeping him or her indoors, and control of the pest population. Cats at highest risk are those that roam and hunt.

Although common, roundworm infections are usually not nearly as serious for your cat as compared to other intestinal parasites. In fact, your cat can have a case of roundworm and still appear quite healthy.

Unfortunately, if the intestines become blocked by a large enough number of worms, roundworm can become life-threatening.

Kittens in particular are at risk. In addition, adult cats with compromised immune systems or certain pre-existing conditions will be at risk, as are older cats.