Victorian health authorities have renewed warnings over links between semi-dried tomatoes and an outbreak of hepatitis A following a further 23 cases of the infectious disease diagnosed in the past week.
Victoria's chief health officer Dr John Carnie said that so far this year there had been 200 notifications of hepatitis A, compared to 74 at the same time last year.
A study into the increase of cases indicates that more than two thirds of people that have become ill recalled eating semi-dried tomatoes, he said.
"Because the incubation period for hepatitis A could be as long as two months, trying to get people who fell ill to accurately pin down what and where they actually ate this product can be difficult," Dr Carnie told reporters on Monday.
"We still are unclear as to why there has been a recent spike in cases in Victoria.
"However, we are continuing to work with the manufacturers and suppliers of semi-dried tomatoes to try and identify the source."
Local producers had promised the Department of Human Services they were doing their best to reduce the risk, while importers of the tomatoes had also been instructed to ensure appropriate quality control measures were in place, he said.
Bottled semi-dried tomatoes in supermarkets were pasteurised and considered safe along with any of the cooked product such as in pizzas or quiches.
The greatest risk would appear to be at restaurants and cafes, where semi-dried tomatoes are served in foods such as salads and sandwiches.
Hepatitis A involves inflammation of the liver and is spread when traces of faecal matter containing the virus contaminates hands, objects, water or food and is then taken in through the mouth.
Symptoms include abdominal pain, nausea, fever and chills, and jaundice.
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