Hi I have just found out one of my cats has round worms. Thank you so much for your time in answering my questions. These two species of worms are transmitted to humans through the ingestion of roundworm eggs which contain infective larvae. Therefore, in an indoor cat, the best protections against infection are proper deworming of the cat and regular cleaning of the litterpan so that stools are disposed of before any roundworm eggs that might be present become infective. For outdoor cats it may be worthwhile to consider routine deworming or regular checks of the cat's stools for infection.
Dogs can acquire roundworm infections from their mothers while in the uterus.
Therefore, it is important to begin to deworm dogs at 2 weeks of age. To the best of my knowledge cats are not able to transfer roundworm infections to kittens in the uterus and therefore it is usually recommended that deworming begin at about 6 weeks of age in kittens as it takes about that long for the infection to reach the stage where deworming medications are effective. There is some fear that roundworms may be passed by a kitten or puppy licking the owner. While the transmission rate through this avenue of infection is probably very very low it is still a good idea to observe good hygiene and wash hands and faces after playing with the kitten or puppy. Occasionally a physician will advise one of my clients to put their cat outside to reduce the risk of infection with Toxocara or toxoplasmosis.