The Centre for Health Protection is investigating the year's third imported case of leptospirosis - an infectious disease caused by bacteria found in the waste of infected animals - involving a 28-year-old man.

The patient came down with fever, stomach upset and leg swelling on July 10. He was admitted to Yan Chai Hospital on July 15 and discharged on July 22.

The man had travelled to Sabah, Malaysia with his friends from June 24 to July 2, but his friends did not have similar symptoms.

There were 10 leptospirosis cases reported last year, three in 2006 and seven in 2005. Risk of infection can be minimised by covering open wounds properly and avoiding contact with urine of live mammals and objects contaminated by them as well as polluted water.

The disease is normally not transmissible among people, and the incubation period is usually five to 14 days. Click here for details.