Abstract: Objective To conduct a field epidemiological investigation and analysis on a local case of leptospirosis in Shenzhen, providing a reference for the prevention and control of leptospirosis in urban areas. Method An epidemiological investigation and laboratory testing were conducted on a leptospirosis case reported in Nanshan District, Shenzhen on November 13, 2024, along with rodent density monitoring at potential exposure risk sites of the patient. Real-time PCR was used to detect Leptospira nucleic acid in the blood and urine samples of the case, as well as in the blood, liver, spleen, kidney tissue, and urine samples of the captured rodents, and in stream water samples. Result The early symptoms of the patient were not obvious. Six days after the onset of the disease, the patient was diagnosed as a suspected leptospirosis case based on Hirsch reaction, and then he was diagnosed as leptospirosis typhi by metagenomic next-generation sequencing and nucleic acid detection. According to the epidemiological investigation, the patient had gone to W scenic spot on foot and traced the creek three times one month before the onset of the disease, during which he was pierced by branches, and the wounds were soaked in creek water. The epidemiological investigation team set up 203 traps along both banks of the stream in the W scenic area and captured 19 rats. The positive rate of leptospira was 36.84%. No other infected persons were identified. Conclusion This patient with leptospirosis has sufficient evidence of local infection. The infection site was determined to be the W scenic area. The mode of infection is through contact with water contaminated by urine of rodents through wounds.

Key words: Leptospirosis, Hirsch reaction, Urban preventionand control, Anepidemiological survey