Encephalitozoon cuniculi in pet rabbits

Encephaliitozoon cuniculi found among pet rabbits from North Yorkshire, UK

source: F.M. Harcourt-Brown and H.K.R. Holloway
Veterinary Record vol 152 no 14, April 5 2003
starts p 427, 5 pages long

Encephalitozoon cuniculi is one of the Encephalitozoon species, and mainly affects rabbits, usually infected by eating food contaminated with infected urine. E cuniculi spores can survive at room temperature for four weeks minimum. Spores multiply in cells, which rupture to release them, causing inflammation, which in turn can lead to lesions. E cuniculi infections can affect other animals such as guinea pigs, hamsters, cats, dogs and humans, with infections reported for AIDs patients whose immune system is suppressed. Infected rabbits may show no symptoms. The most common symptom in rabbits is a head tilt due to vestibular disease. E cunicli can also cause kidney disease, cataracts and uveitis. Laboratory rabbits undergo screening, with infected animals culled.

This study reports testing of 125 pet rabbits by a N Yorks veterinary practice, England, from 1997 -2002, with subsequent treatment of affected rabbits. Rabbits showing symptoms of E cuniculi accounted for 87 of the total. Rabbits living with seropositive companions accounted for 12, and 26 of the sample underwent tests during a health check.

Treatment varied according to the symptoms, with no parasiticidal treatment initially given, until 1998, when fenbendazole and albendazole were used. Fenbendazole alone was used from 2001, in line with a study published that year. Owners decided whether rabbits with no symptoms should be treated.

Eight rabbits were seropositive of the 12 tested because a companion was seropositive, while six (23%) were seropositive of the 26 tested during a more general health check. Neurological signs affected 38 rabbits, and 20 of these lived over six months, with many still showing symptoms but less severely affected. Five rabbits did not receive treatment for neurological signs and still survived, three of them recovering completely. Seven rabbits just suffered ocular lesions, and all of these survived. Three rabbits with renal failure were euthanased.

Antibodies were found in 74 of the total of 125 rabbits, though the results did not differentiate between rabbits with active or latent infections, and those that had simply had an antibody response but no longer had an infection. Little work has been carried out on treating rabbits with Encepalitozoonosis. Some rabbits with neurological symptoms were treated with corticosteroids to prevent an inflammatory response, though corticosteroids could hamper recovery, since they are immunosuppressive.

E cunciuli appears to be an important cause of disease affecting pet rabbits in the UK. More research is needed on how the disease spreads, and there is a need for diagnostic tests as well as licenced products to prevent and treat the disease, especially given its zoonotic potential.