Swine flu deaths will be inevitable, the NSW chief health officer said on Thursday.

The number of confirmed swine flu cases in western Sydney is six, with 44 suspected cases.

The number of confirmed cases in NSW almost doubled in one day to 33, up from 18.

Twenty-four of those were from the Pacific Dawn cruise ship, from which 2000 passengers disembarked from on Monday.

Chief health officer Kerry Chant said another 324 people are undergoing tests.

``The overseas experience is that in a small number of cases deaths have occurred,'' Dr Chant said.

``So if this goes across the Australian community, one would expect that some members of the community will unfortunately die as a result of this.''

Dr Chant said with no vaccine to protect vulnerable people, the swine flu virus could be deadly.

All reported cases in the state were people who had either been on the Pacific Dawn or had returned from overseas after visiting an affected country, with no reported cases of local transmission, Dr Chant said.

``It is possible that there is community transmission or some cases that we haven't detected, but we are doing all we can to look for it,'' she said.

``It is likely we will see an increase in the number of cases as we move into the next few weeks.''

Three crew on the Pacific Dawn cruise ship have tested positive to the virus will return to Sydney on Monday, three days ahead of schedule.

Anyone who has returned from the Mexico, USA, Canada, Japan or Panama in the past week should look out for symptoms including fever, cough, tiredness, muscle aches, sore throat, chills, shortness of breath, runny nose and headaches.

Symptoms will generally appear between two to four days after exposure.

Anyone who has recently returned from the affected areas and who develop any symptoms of breathing difficulties should contact their local public health unit, general practitioner or emergency department.