I have 2 questions to ask
Almost all mamals do have nipples just like it is in human female/males.
The number of mamarian nipples in cats are normaly 6 to 8 but it can vary from 4 to 10 and the numbers are not always even.
More about this here:https://kittyclysm.com/cat-nipples/ if you google cat nipples you will find a lot of information about it.
So the answer to your question is this is not related to fleas it is just mamarian nipples and both female and male cats have them.
(mamarian nipples are the same as breast nipples)