I had two bunnies with e.cuniculi. Bailey showed symptoms of hind leg weakness as she got older, while Rucy never showed symptoms. Actually, it is estimated that 1 in 4 bunnies have been exposed to e.cuniculi and only a small portion will really show any symptoms.
Also, my understanding about a bunny spreading it via urine is that the e.cuniculi parasite has to be active in the kidneys at the time. I have two very different “contagious” stories. My bunny Rucy, who was e.cuniculi negative at the time I adopted her, later tested positive years later. She had lived with Bailey (before Bailey was symptomatic), for a short time, but they ended up fighting, and so I don’t know if it could be passed that way — through a nasty bite or not, but she could have passed it along via urine as Bailey did start showing symptoms. HOWEVER, Rucy, who then ended testing positive, never had symptoms, and her new mate, Jack who was e.cuniculi negative never became positive, (I had him checked after Rucy passed away). And they had lived together for years and they shared a litter box.