A good egg ... always cook eggs before serving and don't use cracked ones. Photo: Michel Osullivan

Now NSW Health and the NSW Food Authority have the difficult task of trying to track down the poultry culprits - possibly from a large Victorian producer - and are investigating whether the incident and three others in Sydney affecting 25 more people are all linked.

"In terms of cases of salmonella from home preparation using raw eggs, we've had four times the year's average in the past six weeks," Peter Sutherland, director of food safety programs at the NSW Food Authority, said yesterday.

The investigation comes as the authority hopes to introduce regulations next year making NSW the second state - after Queensland - requiring individuals eggs to be stamped so they can be easily traced to their farms, thus making producers more accountable for quality.

Mr Sutherland said the other salmonella poisoning cases were: 11 people who fell ill from eating caesar salad made with raw egg dressing at a dinner party at a Carlingford home, three children sick from drinking an eggnog at home in Thornleigh and, most recently, a cafe in Auburn where 11 people had food poisoning after apparently eating cheesecake.