Evaluation of a standardized F1 capsular antigen capture ELISA test kit for the rapid diagnosis of plague

Rapid detection of soluble F1 capsular antigen in serum, bubo fluid or urine of patients proved to be a valuable tool in the presumptive diagnosis of plague. We evaluated a F1 capsular antigen capture ELISA resembling a commercially available test kit. The minimal detectable concentration was 4 ng/ml. The specificity was 100% when investigating 47 sera from healthy Malagasy subjects and 98.4% when 365 sera from German blood donors were studied. Sensitivity was determined on sera (n=11) and buboes (n=18) from bacteriologically confirmed Malagasy plague patients. Sensitivity was 90.1% for serum and 100% for buboes. A standardized F1 capsular antigen capture ELISA test kit might be well suited for the early detection of plague particularly in non-endemic areas where clinical microbiological laboratories have only limited access to alternative techniques for rapid identification of Yersinia pestis.