Assessment of the effect of long-term serum storage for retrospective serologic diagnosis of canine monocytic ehrlichiosis (Ehrlichia canis)

Comp Immunol Microbiol Infect Dis. 2024 Apr 2;108:102170. doi: 10.1016/j.cimid.2024.102170. Online ahead of print.ABSTRACTThere is currently sparse information on the possible effect of long-term storage of serum specimens for the retrospective serodiagnosis of canine monocytic ehrlichiosis (CME). The aim of this study was to assess the agreement between the original serologic outcome and the results of a repeat indirect fluorescent antibody (IFA) assay for the detection of IgG antibodies against E. canis. A secondary aim was to compare the diagnostic performance of two commercially available point-of-care (POC) immunochromatographic (IC) assays. Archived serum samples originally tested as positive (n=66) or negative (n=19) for E. canis IgG antibodies and kept frozen at -20°C for a median of 22 years, were retrospectively examined by IFA and by two POC IC assays. Cohen's Kappa coefficient (0.748, p < 0.0001), indicated a substantial agreement between the original and repeat serologic testing results. An almost identical high sensitivity and moderate specificity were established for the two POC IC assays. Canine serum specimens on long-term storage may still be of value for seroepidemiologic surveys investigating the exposure to E. canis.PMID:38581930 | DOI:10.1016/j.cimid.2024.102170
Source: Comparative immunology, microbiology and infectious diseases. - Category: Allergy & Immunology Authors: Source Type: research