Encephalitozoonosis in Rabbits

Encephalitozoonsis is an infection that can affect the kidneys, eyes and nervous system of rabbits. It’s caused by an organism called Encephalitozoon cuniculi or E. cuniculi, a small microsporidian parasite that’s intracellular (it has to live within another cell).

Encephalitozoonosis can affect rabbits, mice, hamsters, dogs, cats, guinea pigs and humans. It usually causes a latent condition in rabbits, meaning that most infected rabbits will show no symptoms.

How could my rabbit become infected with encephalitozoonosis?

istock_000008563562_extrasmallRabbits get infected in two ways:

  • From the urine of other infected animals. For example, your rabbit may eat a contaminated food source containing spores of this organism that have been passed in the urine. The spores reproduce in the new host (your rabbit, for instance), until they too are passed in the urine.
  • From the mother. E. cuniculi can be passed by the mother to the unborn baby (in utero infection). In utero infections may reside in the lens of the eyes.
“Rabbits get infected in two ways: from food contaminated with the urine of an infected rabbit, or from the mother.”

What are the symptoms of encephalitozoonosis in rabbits?

Most infected rabbits don’t show any signs or symptoms until the rabbit is perhaps older, stressed or immunocompromised. In addition, some rabbits may not develop problems even though they’re infected.

If your rabbit is infected and symptoms do develop, you may see any of the following. If left untreated, the disease can progress and produce more severe symptoms.

  • Heavy white cataracts in one or both eyes
  • A head tilt due to its involvement with the nervous system
  • Twitching eyes (nystagmus)
  • Anorexia (absence of appetite)
  • Difficulty walking
  • Tremors and seizures

How does my veterinarian diagnose encephalitozoonosis in rabbits?

Your veterinarian can make a presumptive diagnosis based on clinical signs and eliminating other diagnoses. Sometimes a diagnosis is presumed based on a rabbit’s response to treatment.

In addition, your veterinarian may run blood tests, which may be positive (but only that the rabbit has been exposed to the organism; not that it’s infected).

It’s possible to make a more definite diagnosis after an animal has passed away. If there’s more than one rabbit in the household, this is helpful so the other rabbits can be treated.

How does my veterinarian treat this infection?

Currently there are no particularly effective drugs to treat the disease; however, this may change in the near future as different drug protocols are being used with various degrees of success. At present, your veterinarian may try a variety of treatments to support sickly animals, and any cataracts can be surgically removed. However, infected rabbits often have little to no response to medical treatment.

If the rabbit declines in health, humane euthanasia may be a loving consideration.

Do I have to worry about Encephalitozoonosis affecting me and my family?

Encephalitozoonosis infections in humans are poorly understood. The condition has been described in a few cases in people, and it’s reported that very young, elderly and immunocompromised people are most at risk. This underlines the importance of always washing your hands after handling any animal and before eating or preparing food.

"This underlines the importance of always washing your hands after handling any animal and before eating or preparing food."

If you have any doubts about your rabbit and his/her health, we encourage you to consult a veterinarian who’s familiar with rabbit care.

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