Objective   To study the feasibility of flaB-PCR in the detection of leptospira existed in animal tissues and to establish a rapid and useful technique for the use of epidemiological investigation of leptospirorosis, which better than those methods traditionally used.

  Methods   A pair of oligonucleotide primers of flaB were synthesized according to the sequence of flaB, which high conserved in Lai strain of leptospira icterohaemorrhagiae.the DNA of leptospira in experimental animal samples and in frog kidney specimens were detected by PCR with this pair of flaB primers.

  Results   The DNA of leptospira interrogans could be amplified specifically by the primers.Whereas, the DNA of other bacteria used in this study had no amplification at all.10 leptospira in samples could give a positive PCR result on 1.5% agarose gel electrophoresis.10 of 26 tissues of experimental animals infected with leptospira were positive by flaB-PCR, the positive rate was 38146%.However only 2 strains were isolated from them and with the positive rate of 7.69%, the difference between flaB-PCR and isolation was significant(χ ²=6.63, P < 0.01).70 specimens of frog kidney from Anhui province were tested by flaB-PCR and isolation synchronously.8 of them were positive by culure and 14 by PCR, the positive rate was 11.43% and 20% respectively.

  Conclusion   flaB-PCR is a high sensitive, specific and rapid detecting mean, which can be used as a powerful tool in surveillance of epidemic situation and epidemiological investigation of leptospirosis.