Seroprevalence of Encephalitozoon cuniculi and Toxoplasma gondii antibodies and risk-factor assessment for Encephalitozoon cuniculi seroprevalence in Finnish pet rabbits (Oryctolagus cuniculus)

BACKGROUND: Neurological signs, such as head tilt, torticollis, paralysis, and seizures, are common in rabbits. Differential diagnoses include two zoonotic infections caused by the microsporidial fungi Encephalitozoon cuniculi and the apicomplexan protozoa Toxoplasma gondii. Both infections are mainly latent in rabbits but may cause severe or even fatal disease. Although several international studies have reported the seroprevalence of these pathogens in different commercial rabbit populations, similar prevalence studies and risk-factor analyses among family-owned pet rabbits are uncommon and lacking in Scandinavia. We sought to estimate the seroprevalence and possible risk factors for E. cuniculi and T. gondii among Finnish pet rabbits. We used ELISA to measure E. cuniculi IgG seroprevalence of 247 rabbits and modified direct agglutination test for T. gondii seroprevalence of 270 rabbits. Samples were collected as part of the Finnish Pet Rabbit Health Research project. Internet-based questionnaires (n = 231) completed by the rabbit owners were used for risk-factor analysis. RESULTS: The apparent seroprevalence of E. cuniculi was 29.2% and true seroprevalence of T. gondii 3.9%. Risk factors were analysed only for E. cuniculi due to the low T. gondii seroprevalence. The final multivariable logistic regression model revealed that rabbits spending the whole summer outdoors had a higher risk of being E. cuniculi seropositive than rabbits with limited outdoor access. Additionally, rabbits living in households with only one or two rabbits had higher risk of being E. cuniculi seropositive than those in multi-rabbit households. CONCLUSIONS: Nearly one third of Finnish pet rabbits participating in this study had E. cuniculi IgG antibodies, indicating previous exposure to this pathogen. The prevalence is similar to that reported previously in clinically healthy rabbit populations in UK and Korea. While the seroprevalence of T. gondii was low (3.9%), antibodies were detected. Therefore, these zoonotic parasitic infections should be considered as differential diagnoses when treating rabbits.