UTILITY OF IGM TITERS WITH IGG AND C-REACTIVE PROTEIN QUANTITATION IN THE DIAGNOSIS OF SUSPECTED ENCEPHALITOZOON CUNICULI INFECTION IN RABBITS

The objective of this study was to evaluate the utility of measuring IgM, IgG, and C-reactive protein (CRP) levels in rabbits with suspected Encephalitozoon cuniculi (ECUN) infection. Serum samples from 130 pet rabbits were submitted from veterinary clinics within the United States. Participating veterinarians completed a questionnaire that was used to classify rabbits as either non-ECUN suspect (n = 36) or suspected of having ECUN infection (n = 94). An enzyme-linked immunosorbent assay was used to detect IgG and IgM titers against ECUN. In addition, an immunoturbidimetric assay was used to detect CRP. In all, 50% of non-ECUN-suspect rabbits were IgG positive vs 95% of ECUN-suspect rabbits. When comparing the results from the 2 groups, higher titers of IgM and IgG and elevated CRP levels were observed in the ECUN-suspect group (P < 0.05). When examined alone, the positive predictive values of IgM, IgG, and CRP varied from 88% to 90%. The use of combinations of these tests decreased the sensitivity of the diagnostic panel but increased the specificity resulting in a positive predictive value ranging from 92% to 100%. These data suggest that the use of multiple immunological tests appears helpful in diagnosing ECUN in rabbit patients exhibiting clinical signs consistent with infection. Copyright 2015 Elsevier Inc. All rights reserved.