RESUMEN
The utility of IgA class antibodies for the serodiagnosis of cat scratch disease (CSD) was evaluated by developing an indirect immunofluorescent assay (IFA) using an antigen obtained by co-cultivating Bartonella henselae ATCC 49882 with Vero cells. Served for evaluation were 101 sera from patients serologically confirmed as CSD with IgG-IFA ≥1:256, and 144 sera from patients clinically suspected of CSD but not serologically confirmed. The sensitivity of the newly developed IgA-IFA in detecting the confirmed cases was 57.4% (58/101), and 75.0% in combination with IgM-IFA. As for the non-confirmed cases, IgA-IFA turned 8.3% cases (12/144) positive, 10 of whom were subsequently diagnosed as CSD of early stage from clinical courses and/or by repeated testing. The 12-case gain was regarded as a significant improvement. Hence, the diagnostic rate of early-stage CSD is expected to be increased by routinely performing IgA-IFA in addition to conventional IgG/IgM-IFA.