Australia's 10th confirmed case of influenza A H1N1 (swine flu) has appeared in Adelaide in South Australia - the first case for that state.
The 15-year-old girl is the second Australian to contract the disease by way of person-to-person with her parents and brother.
The health department says the girl has not travelled overseas recently but has travelled interstate.
The school the girl attends, Eynesbury College in Adelaide, has been closed for a week, with around 400 students told to remain at home and the college's principal, John Warren, says 40 of the girl's Year 10 schoolmates will be given antiviral treatment as a precaution and are not considered to be at any great risk.
South Australian health officials say the girl was given anti-viral treatment on Tuesday but tested positive to the H1N1 strain late yesterday; they say she is young and healthy and can be expected to make a full recovery.
Health authorities say a precautionary approach has been adopted in order to limit the spread in Australia.
Victorian health officials say they are expecting more cases of swine flu to appear in the state after two more cases were confirmed last night and test results are pending for another nine suspected cases.
To date in Victoria 6 people are now reported to have the virus in the state - a 10-year-old girl and a 25-year-old man are the latest confirmed cases - a female classmate of a young boy with the disease was last night also reported to have contracted the virus.
Victoria's acting chief health officer Rosemary Lester says health officials are trying to trace passengers on the 25-year-old man's flight, which arrived from Los Angeles last Tuesday.
The girl is a pupil at the Clifton Hill primary school, where there has been a cluster of swine flu cases which have been traced to the Dicksons family , who recently returned from a holiday in California, who were confirmed to have the H1N1 human swine-flu virus - Danny, 10, and younger brother Adam, 9, went to school on Monday while they were infectious and older brother Josh, 12, played sport last weekend and came into contact with some young players.
The school will remain closed until next week while government health officials carry out a pre-emptive strike against the virus at a number of schools and sporting venues.