Early diagnosis of bubonic plague using F1 antigen capture ELISA assay andrapid immunogold dipstick

Plague is still prevalent in more than 20 countries. Two F1 antigen diagnos tic assays tan immuno-capture ELISA and an immunogold chromatography dipsti ck) were evaluated using bubo aspirates, serum and urine specimens from pat ients suspected with plague. The specificity of the two F1 assays was found 100 %. Using bacteriology as a gold reference diagnostic assay, 52 patients were Y ersinia pestis culture positive and 141 negative. The sensitivity of the F1 ELISA test was 100 % in bubo, 52 % in serum and 58 % in urine specimens. I n culture negative patients, the F1 antigen could be found in 10 % bubo asp irates;, 5 % serum and 7 % urine specimens of culture negative patients for whom a seroconversion for anti-F1 antibodies was also observed. The sensitivity of the dipstick assay was 98 % on bubo aspirates specimens. Compared to the ELISA test, tbe agreement rate was 97.5 % and the correlat ion coefficient tau = 0.90 (p < 10(-3)). In conclusion, the diagnosis of bubonic plague has to be performed on bubo fluid rather than on serum or urine specimens. Both the F1 ELISA and the di pstick assays are valuable tools for an early diagnosis and for the surveil lance of plague.