The outbreak, which affected 140 people and hospitalised 15 in mid-May, was traced back to raw egg mayonnaise served at the Copa Brazilian restaurant in Dickson. But ACT Chief Health Officer Dr Paul Kelly confirmed on Wednesday that the focus had turned to an egg producer in Victoria who supplied eggs to the Copa.

''We have actually sourced the eggs back to a supplier in Victoria, and our colleagues in Victoria have commenced an investigation of that particular place,'' Dr Kelly said.

''They've gone out to that particular farm, and there's been a veterinarian inspection. What normally happens there is that they also take some swabs and some eggs for the same sort of testing that we've done.''

He said the investigation into the outbreak was now looking to isolate the ''molecular fingerprint'' of the particular strain of salmonella using highly specialised lab work, which would then allow the authority to more definitively identify the likely source.

Dr Kelly said so far results were pointing towards typhimurium phage type 170 as the specific bacterium, and clinicians at the territory's hospitals had told ACT Health they'd never seen an outbreak with such strong symptoms.

''We were really struck by the severity of the symptoms and also the high attack rate - almost everyone that ate there got sick,'' Dr Kelly said.

Of those treated, all patients had diarrhoea, but 94 per cent also had abdominal cramps, and 92 per cent had fever - which Dr Kelly said was ''surprisingly high'' and pointed towards a very large dose of the bacterium in the food.

He also confirmed that one person had presented with ongoing joint issues as a result of the salmonella.

''Hopefully that will resolve. Normally it does, but sometimes it doesn't, it continues. The thing is, just on probability, the more cases you have, the more likely you're going to have these quite rare ongoing events like this,'' he said.

At the height of the investigation, ACT Health had up to 30 people working on the case at any given time. Workers contacted 194 diners, often more than once, for interviews that could last more than 30 minutes, and also conducted inspections at the restaurant, questioned the business owners and staff, and processed a large stream of data coming in about the infection.

Dr Kelly confirmed ACT Health was monitoring the Copa since it reopened about a week after the outbreak. He said the authority established a short period of increased inspections for the establishment, and sofar had not discovered any issues.

''They're fine. They'd done a complete refit before the incident, so there wasn't any of that sort of hardware problems to fix,'' he said.

''Really, it was just the raw eggs. I really wish people would just stop using them.''

Dr Kelly said of 10 food poisoning outbreaks last year, half were salmonella-related, and four of those were traced back to raw egg products. He would like to see a national approach to combating the issue. ''At the moment there's no law against using raw eggs. There is a law under the Food Act in the ACT and in other jurisdictions about … supplying unhealthy food to people. That is a breach of the law. I would argue that supplying food that has salmonella in it is pretty unhealthy,'' he said.

Dr Kelly said ACT Health would continue to work closely with suppliers and the ACT's 2500 food establishments to find a solution.