[Investigation on the rate of urinary excretion of leptospires among cattle naturally infected with Leptospira interrogans].

Urine samples of Leptospires from cattle were detected by polymerase chain reaction (PCR) and isolation. Positive rates by Southern-blot and agarose gel electrophoresis of PCR amplification productions were 13% and 11% respectively. Positive rate of isolation was 3.1%. Various positive rates by PCR for cattle urine from different areas were discovered. Average rate of urinary excretion of Leptospires among cattle that naturally infected with Leptospira interrogans was 13.2%. Data showed that cattle was a major source of infection of Leptospirosis in some parts of China. According to the comparsion of results between PCR and isolation, we believe that PCR is a sensitive, rapid and simple method for the investigation on source of infection of Leptospirosis.