Hi Berry mum,
A very similar situation to this was encountered in the 2002 High Court of Australia case of
Graham Barclay Oysters Pty Ltd v Ryan [2002] HCA 54 in which customers at a restaurant contracted Hepatitis A after consuming contaminated Oysters. The contamination was found to be caused by heavy rain run off into the lake where the oysters were farmed. The injured persons sued the distributors of the Oysters, the council and the state claiming that they were negligent.
The High Court held that the distributor of the oysters, although they owed a duty to customers to take reasonable care to ensure their oysters were fit for human consumption, they did not breach that duty and were not liable.
However the plaintiffs were successful in an action under the Trade Practices Act (now the
Consumer and Competition Act 2010 (Cth), which includes the Australian Consumer Law and its consumer guarantees) alleging that the oysters were not fit for purpose or of merchantable quality.
Whether or not you will have recourse to sue Patties Foods (owner of the Nannas brand) in this situation if you do contract Hepatitis will depend on how the berries became contaminated and whether this was due to a lack of due care or negligence on the part of the Patties Foods.