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Encephalitozoon cuniculi (E. cuniculi)

A common cause of head tilt in Rabbits


1. What are E. cuniculi  and where are they found?

E.cuniculi are microscopic protozoan parasites that are often found in the kidneys and brain. Lungs, heart, and liver can also be infected. The infective spores are passed in urine for up to 3 months after initial infection.


2. What is the route of transmission?

E.cuniculi spores are often ingested or inhaled through food or soil contaminated with infected urine. The spores are environmentally resistant and can survive on the ground for several weeks or months.


3. What are the clinical signs of E. cuniculi infection?

Signs depend on what organs are infected. Infection may lead to cysts in the brain. This can cause some or all of the following signs:

·      Head tilt

·      Nystagmus (fast, repetitive eyeball movements)

·      Inability to balance eg rolling

·      Seizures

However some rabbits can carry these organisms and not show any signs of illness. A stressful event can lead to the sudden development of symptoms.


4. How is E. cuniculi diagnosed?

The clinical signs (head tilt) are most commonly used to diagnose this disease. Other causes of head tilt such as trauma, ear infections, and abscesses need to be ruled out. Blood tests can be used to confirm the presence of the parasite by determining high or increasing levels of antibodies. It can be difficult to distinguish between acute, chronic or past infection without repeated blood tests. A young rabbit up to 4 weeks old may have antibodies passed through blood by its mother. If infected after this age, the young rabbit’s antibodies gradually rise and reach highest levels at 14 weeks of age.


5. What is the treatment for E. cuniculi infection?

Treatment involves drugs such as Fenbendazole to kill the parasite. However killing the parasite does not usually decrease the clinical signs of head tilt. Anti-inflammatories may help reduce the severity of the head tilt.

Treatment of secondary infections with antibiotics may also be necessary.


6. How is E. cuniculi infection prevented?

·        The enclosure should be cleaned thoroughly daily and then disinfected.

·        Quarantine all new rabbits for 6-12 weeks or until they are tested for E.cuniculi.

·        Place food and water bowls off the ground to prevent contamination.


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