E. cuniculi

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What is it?

Encephalitozoon cuniculi (E. cuniculi) is a parasite that lives inside living cells, found in rabbits and other species. The disease it causes is Encephalitozoonosis which results in severe damage to the brain, kidneys and/or eyes.

Why is it important?

It is a common disease in pet rabbits (52% of UK rabbits showed positive to exposure on blood testing in 2009). The infection is spread via spores excreted in the infected rabbit’s urine (also faeces and mucus, at lower levels).

What’s the risk?

Rabbits become infected by eating or inhaling the spores, they are also passed during pregnancy from the doe (mother) to kit (baby).

The infection appears to be within the pet rabbit population only (although wild rabbits can be infected). This is thought to be due to the toileting habits of wild rabbits, which reduce exposure to urine, and therefore minimise the spread of the infection. The spores can survive in the environment at 22oC for a minimum of 4 weeks.

What happens to the rabbit?

Once the spores are in the body they are carried in the bloodstream and settle in certain organs. Clinical signs can be severe and mainly affect one or more of the following three body systems: the central nervous system (brain), kidneys or eyes.

The exact symptoms can depend on whether the infection was recent (acute) or a while ago (chronic).

Acute infection can show very severe signs:

  • Loss of balance
  • Head tilts
  • Seizures
  • Sudden death
  • Chronic:

  • Swaying or head-nodding when resting (may appear to be ‘nodding off’)
  • Staring at the sky/ceiling for no reason
  • Change in behaviour/aggression
  • Deaf/Blind
  • Urinary incontinence/uneaten caecotrophs
  • Wobbly/loss of balance
  • Kidney infection:

  • Drinking/urinating more
  • Urinary incontinence
  • Kidney failure (on blood or urine tests by your vet)
  • Eye infection:

  • Cataracts
  • Blindness
  • Floating white/yellow bits in the eye
  • A painful eye (holding it closed/uneven pupils)

  • How do you know what’s going on?

    Blood samples can be taken to test for antibodies to the disease; however, a positive result will only confirm a rabbit has been exposed to E. cuniculi at some point in its life, not whether it is currently infected.

    A test can be run on urine called a PCR which detects E. cuniculi DNA, however infected rabbits will shed the spores irregularly and you may get a test result which is falsely negative.

    In the event of sudden death, a post mortem can be carried out and samples sent off for testing – this is of particular importance if there are other rabbits in the household which may be at risk.

    Diagnosis is made by a vet based on a collection of clinical signs, response to treatment and/or blood or urine testing.

    What can be done?

    Treatment options aim to reduce shedding of spores and repeat exposure to them. Fenbendazole is currently the only drug available proven to resolve infection in positive rabbits and prevent infection in newly exposed animals, it must be used for a minimum of 28 consecutive days. This will treat the infection, but the associated signs (neurological, mobility, urinary etc.) need specific treatment alongside this so please see your vet urgently; do not start treatment with fenbendazole without seeking advice first.

    What can I do to protect my pet?

    Control and prevention of the disease can be difficult as chronically infected rabbits don’t always show signs. Always monitor closely for any indication of infection - see a vet urgently if you have any concerns.

    Take care introducing new rabbits – some may have signs of previous or current infection with E. cuniculi such as head tilts, drinking or urinating more, cataracts in the eyes etc. whereas some may show no signs at all. Blood tests can be taken to check for exposure to disease before introduction to reduce the chance of exposing a negative rabbit to a positive one. If blood testing is not an option then treat with fenbendazole (again, for at least 28 days) before introduction.

    Good hygiene can limit exposure to urine and faeces when under treatment. Although spores can survive for over 4 weeks in the environment, they can be eradicated with certain disinfectants following a deep clean.