21.   All patients were infected with HIV, the virus that causes AIDS.

22.   But in rare cases, patients have been infected by their surgeons or anesthesiologists.

23.   French health authorities said the incident is only the second known case in which a health professional has infected a patient.

24.   How the patients were infected was a mystery.

25.   However, Dr Lee said with the incubation period of the HIV virus it was difficult to tell by whom a patient was infected.

26.   No other patient was infected, it said.

27.   Tests showed that only about half the patients were infected with either of the two bacteria.

28.   The case, French authorities said, was only the second known case in which a health professional has infected a patient.

29.   The case, French authorities said, was only the second known case in which a health professional infected a patient.

30.   The health authorities which employed Ngosa stressed the risk of him infecting patients was remote.