E.Cuniculi & Your Rabbit

Over the weekend we sadly had a rabbit who very likely died of an E.Cuniculi infection. We thought it would be a good idea to compile some information which can be useful for rabbit owners. Thank you to our nurse Amy Davison for putting this together.

What is E.Cuniculi?

E.cuniculi, or Encephalitozoon Cuniculi, is a tiny protozoan parasite, which lives inside a rabbit’s body and causes encephalizoonosis.

All rabbit owners should be aware of it as it can, occasionally, infect humans, especially if they are already susceptible to illness (i.e. immunosuppressed, the young and the elderly).

E.cuniculi infection has been diagnosed in rabbits in Europe, Africa, America and Australia. In the UK the parasite is common in laboratory and pet rabbits, but rare in the wild.

Encephalitozoon cuniculi.jpgphoto from dailyparasite.blogspot.co.uk

How is it transmitted?

Once a rabbit has E.cuniculi it passes on the infection through spores in its urine. Other rabbits pick up the disease by eating these spores in urine-contaminated food and water. Unborn kits — baby rabbits — may also be infected during pregnancy.

Once the parasite has entered a rabbit’s body it is carried in the blood to organs such as the liver, kidney and central nervous system (brain and spinal cord). This results in rupture of these cells, inflammation and clinical signs, primarily in the liver, kidney, brain and spinal cord. Only a small percentage — around 6% — of pet rabbits ever show signs of the disease. Some of these rabbits do not survive.

How can I tell if my rabbit has E.cuniculi?

If kits are infected during pregnancy, affected spores are able to cross into the eye. Later on in the rabbit’s life (6months to 2years) these spores multiply and erupt causing cataracts and lens rupture. This results in inflammation within the eye (uveitis), which is a serious and painful condition.

Clinical signs in adult rabbits can include:

  • neurological disease — head tilt, unsteadiness, weakness of the hind legs, neck spasm and urinary incontinence
  • kidney disease
  • eye disease

Other causes of head tilt and neurological disease in rabbits should be ruled out, such as spinal trauma, inherited congenital abnormalities (‘splay leg’), abscesses, middle ear infections, listeria infection, toxoplasma infection and lead toxicity.

bunny head tilt.jpgPhoto from http://www.kingswoodvets.co.uk

Diagnosis, treatment and prognosis

A blood test can be performed to measure antibodies, however the helpfulness of this is limited as it only tells us that the rabbit has been exposed to E. cuniculi at some stage in its life. In a recent study, over 50% of healthy rabbits were found to have E. cuniculi antibodies, which makes interpretation of blood results difficult.

So, if the rabbit is showing signs of disease that are suggestive of encephalitozoonosis, a positive test does not necessarily mean that the parasite is causing these signs.

More information indicating the stage of infection and immune response can be obtained by taking two blood samples one month apart. Rising antibody levels between the two blood samples is suggestive of a current, active infection or flare up. Unfortunately, if the antibody levels are the same at the first and second blood sample, then no true conclusion can be reached.

If the antibody levels to E. cuniculi are falling between samples, then this is suggestive that the rabbit is recovering from a recent infection. This would imply that a treatment regime is having a positive effect.

In affected rabbits the inflammation and release of spores results in clinical signs, particularly affecting the target organs (brain, spinal cord and kidney).

When clinical signs are advanced, only supportive care can be implemented as there is currently no treatment that will reverse the damage already caused by the parasite. Symptomatic treatment can be provided to support the signs of bladder or nervous system disorders.

Treatment is aimed at reducing inflammation, using anti-inflammatory drugs such as steroids and killing the parasite. Treatment generally involves anti-inflammatory medication together with an anti-parasiticide (Panacur) which is taken daily for 28 days.

Response to therapy is dependent on the severity of the infection at the time of diagnosis, if left untreated the infection can prove fatal.

The organism can survive in the environment (e.g. a house or a hutch) for one month. However, the parasite is sensitive to routine disinfectants such as bleach 1-10% for a minimum of 30 seconds.

Control and Prevention

In an ideal world, all rabbits would be blood tested at birth and kept isolated until the test results were known (generally two to three weeks). Only rabbits testing negative for the disease would be kept meaning a disease-free colony could be established. However, it is not an ideal world….

These are some of the scenarios that should be used to control E.cuniculi:

  • You have a new single rabbit

Either pre-emptively treat it once daily for 28 days or blood test it, if negative repeat in one month, if either test positive, treat for 28 days once a day.

  • You have one or more rabbits and are concerned they might be infected

Blood test all the rabbits, if negative repeat in one month. If either test is positive, treat all the rabbits once a day for 28 days. If negative do not introduce any more rabbits without testing or treating it, or treat all rabbits in the household once daily for 28 days. Clean and disinfect the environment on a weekly basis during the 28 days.

  • You have a group of rabbits and one is found to be infected with E.cuniculi

All rabbits in the group should be treated with Panacur for 28 days. The rabbits’ environment should be cleaned and disinfected each week, until the end of treatment.

  • A new rabbit is to be added to a ‘clean’ group of rabbits

Treat the new rabbit for 28 days with Panacur and keep it separate from the others, for at least the first 14 days.

The more rabbits you keep together, the greater the risk of infection. Given this, we recommend that all rabbits coming into a large group are treated for 28 days with Panacur. Once this treatment is complete, they should be kept in clean accommodation, with other previously treated rabbits.


If you are concerned about this parasite, or have any other health questions regarding your bunny, then please do get in contact with us by calling your local surgery.





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