I’m very sorry your bun got EC. It can be a grave disease, as you know, and it’s not known why some buns recover and some buns dont.

In my opinion, a doe that has tested positive for EC should not be bred. The babies have a high likelihood of getting infected in the womb. I dont know if all babies absolutely will become infected, but it is clear that infected does can pass the parasite on to her fetuses in the womb.

EC is quite common, but how common it is, is not fully known, because most buns never display symptoms. Several symptoms are also easily mistaken for something other than EC. EC “attacks” organs with high blood flow, for example the kidneys and the heart, and causes damage there. We most often think of EC as a neuro disease, but it can affect many other organs beside the nervous system, for example the gut.

I dont think female rabbits are more at risk than male rabbits.

I am really sorry you went through this.

I agree with Bam, no animal that is a marked carrier of any disease should be bred. There is not a certainty that the babies will have it, but they are very likely to pick it up from her.

EC is opportunistic in most cases. Lots of rabbits (like the mother) can host it, and never actually be effected by it, because their immune system can keep it in check. For whatever reason, some rabbits are not as resilient and become ill with it almost immediately upon exposure to the disease. Others, carry it asymptomatically,  until their immune system is otherwise compromised (stress/other illness) and then the disease becomes active in them. Sometimes there is no obvious reason as to what triggers that immune weakness. It can be something as simple as moulting, getting a fright or just the changing of the season.

I would advise looking for a different breeder altogether if I were you.