Here's an interesting fact did you know that roundworms can lay dormant in the cats body which has an effect on females as when they become pregnant the hormonal change indicates to the pupas that they can now infect the foetus via nipples/milk. This can lead to to a severe infection!!
Roundworms can also infect humans euuuuuuwwwwww! & that most of us may have a had a roundworm infection without our knowledge!
So 'prevention definitely better than cure' imo