Victoria’s Department of Health and Human services said that it expects more cases of salmonella poisoning following a series of incidents related to the outbreak that led to the recall of some lettuce products on Thursday. Fifty-four people in Victoria were diagnosed with the strain of virus while two people were hospitalised after consuming leafy products linked to Tripod Farmers.

Following the outbreak, Tripod Farmers, based in Bacchus Marsh, located to the west of Melbourne, has taken off as many as 30 products from supermarket shelves, and has launched an investigation to trace the source of salmonella.

The Department has confirmed that the outbreak has been contained, but said that it will continue to investigate the source along with the company and the local council.

“It could be a number of things – the irrigation water, the water the lettuce is grown with, it can be something in the washing process,” the ABC quoted Food Safety Information Council spokeswoman Lydia Buchtman as saying. “It can be someone who’s ill who’s actually handling the food.”

A national recall of all packaged lettuce products was effectuated by Australian health officials following the outbreak. The products were mostly sold through supermarket chains like Woolworths, Coles, Bi-Lo and Safeway.

Finn Romanes, the senior medical adviser at Victoria’s Department of Health and Human services, said that he expected more cases of the poisoning to come up in the coming days. According to him, salmonella hits within six to 72 hours of ingestion, the New York Times reported.

Salmonella infection causes gastroenteritis lasting up to a number of days. Though it is not a fatal infection, the Department has warned elderly people, young children and those with compromised immune system to be very careful.

The Sydney Morning Herald reported that, five more products have been found to have responsible for the outbreak. These include, Woolworth’s Gourmet Mix, 100g, Supa Salad ALH, 1kg, Clear Film Blend, Clear Film Spinach and Clear Film Cos.