Barth Charlotte, Straubinger Reinhard K, Müller Elisabeth, Sauter-Louis Carola, Hartmann Katrin
Clinic of Small Animal Medicine, LMU University of Munich, Munich, Germany.
Vet Clin Pathol. 2014 Jun;43(2):180-4. doi: 10.1111/vcp.12131. Epub 2014 Mar 5.
Anaplasma phagocytophilum is common in dogs, but the best way to diagnose an infection is still not determined. Antibody detection assays are frequently used in veterinary practice. Additionally, polymerase chain reaction (PCR) is available for detection of A phagocytophilum DNA. It is still unknown, how well different diagnostic methods correlate.
The aim of the study was to compare 2 antibody detection assays, an immunofluorescence assay (IFA) and the ELISA SNAP4Dx, and to determine the correlation of these assays by evaluating the sensitivity and specificity compared with PCR as a direct detection method of the organism.
Sera of 200 prospectively included dogs were tested for antibodies to A phagocytophilum using IFA and SNAP4Dx. DNA of the organism was detected by PCR on whole blood. Sensitivity, specificity, and predictive values, including their 95% confidence intervals, were calculated for IFA and SNAP4Dx in relation to PCR.
Four of 200 animals were PCR-positive. Sensitivity of IFA and SNAP4Dx was 100% (95% CI 51.01-100). Specificity of IFA was 52.9% (95% CI 50.42-64.17) and that of SNAP4Dx, 57.4% (95% CI 45.83-59.70). Agreement of the 2 antibody tests was fair (κ 0.334).
Immunofluorescence assay and SNAP4Dx were very sensitive and therefore can be useful as screening tests for A phagocytophilum infection. However, the specificity was low, and agreement between both antibody tests was insufficient. This could be due to either false-positive antibody test results, or false-negative PCR results in dogs that were actually infected.
嗜吞噬细胞无形体在犬类中很常见，但诊断感染的最佳方法仍未确定。抗体检测方法在兽医实践中经常使用。此外，聚合酶链反应（PCR）可用于检测嗜吞噬细胞无形体DNA。不同诊断方法之间的相关性如何仍不清楚。
本研究的目的是比较两种抗体检测方法，即免疫荧光试验（IFA）和ELISA SNAP4Dx，并通过评估与作为该病原体直接检测方法的PCR相比的敏感性和特异性来确定这些方法的相关性。
使用IFA和SNAP4Dx对200只前瞻性纳入的犬的血清进行嗜吞噬细胞无形体抗体检测。通过对全血进行PCR检测该病原体的DNA。计算IFA和SNAP4Dx相对于PCR的敏感性、特异性和预测值，包括其95%置信区间。
200只动物中有4只PCR呈阳性。IFA和SNAP4Dx的敏感性为100%（95%CI 51.01-100）。IFA的特异性为52.9%（95%CI 50.42-64.17），SNAP4Dx的特异性为57.4%（95%CI 45.83-59.70）。两种抗体检测方法的一致性一般（κ 0.334）。
免疫荧光试验和SNAP4Dx非常敏感,因此可用作嗜吞噬细胞无形体感染的筛查试验。然而，特异性较低，两种抗体检测方法之间的一致性不足。这可能是由于抗体检测结果假阳性，或实际感染犬的PCR结果假阴性。
