The cat roundworm Toxocara cati can infect humans as well. In other words your cat could transmit a roundworm infestation to you1. Although, to the best of my knowledge, it is relatively rare.
Europeans are recommended to administer monthly deworming pills to dogs and cats under the European Scientific Council Companion Animal Parasites (ESCCAP) advice. They ascertained that people dewormed their cats 2.2 times per year on average. This is clearly well short of once a month.
They also ascertained that 54% of cats fell into the highest risk group in terms of the risk of acquiring a worm infestation. Incidentally, 93% of dogs also fell into the highest risk group.
The conclusion is that improved treatment compliance is required in order to reduce the zoonotic (transference of a disease from animal to human and vice versa) risk to humans and to improve cat and dog health.
1. Other endoparasites are also zoonotic: Toxocara spp., Echinococcus spp., Taenia spp., Dipylidium caninum, Dirofilaria spp. and Thelazia callipaeda.
2. The study referred to for this information: Survey of European pet owners quantifying endoparasitic infection risk and implications for deworming recommendations. Published November 1st 2018 on ncbi.nlm.nih.gov.
P.S. My cat catches and eats mice from time to time. I stopped deworming him a long time ago and I feel guilty but he looks in rude health. His coat is great and there is nothing wrong with him health wise. But I will get some more deworming pills and administer them. I hate to say it but I am not convinced that he needs deworming monthly.