A recent question:
"I have two rabbits who just tested positive for E. cuniiculi... Can you please tell me how to disinfect my floors and kill the parasites? I don't think bleach is doing it."
Encephalitozoon cuniculi is a strange little bug. It a member of a unique group of organisms called microsporidia. Originally thought to be parasites like Giardia, they are now classified as a type of fungus. Regardless, E. cuniculi is common in the pet rabbit population, causing neurological disease in some rabbits but living in many others without any signs of illness.
Infected rabbits shed E. cuniculi spores in urine, feces and respiratory secretions. Other individuals are infected by ingesting (and possibly inhaling) these spores. Infected rabbits start to shed spores in urine a month or two after infection, and can continue to shed low levels of spores intermittently. This, along with close housing of pet rabbits and movement of rabbits between breeders, stores and owners, explains why, in some studies, up to 75% of tested rabbits have evidence of current or prior infection.
Disinfecting household environments can be tough because of the surfaces that are involved. Encephalitozoon cuniculi is quite hardy and can live in the environment for prolonged periods of time. It is susceptible to a several types of disinfectant, including bleach, 70% alcohol and 1% hydrogen peroxide. In general, bleach is highly effective and is probably the standard for disinfection of surfaces that can tolerate it. Obviously, bleach isn't a good option for many surfaces like carpets. Steam cleaning might help, as much for the thorough cleaning component as for the steam.
One thing to consider is whether aggressive household disinfection is really required. While humans can be infected, infections are uncommon and predominantly occur in people with compromised immune systems, especially those with HIV/AIDS. If there are no high-risk people in the household, I don't think I'd be too aggressive with disinfection. Good hygiene practices involving handling of the rabbits and their cage are probably much, much more important, and its better to focus efforts there. Household disinfection for protection of the rabbits is probably not too useful at this point. I would suspect that all rabbits in the household have already been exposed, and since infected rabbits can continue to shed intermittently, rabbits are a much greater source of infection than the household environment.
More information about E. cuniculi can be found in our archives.