Three more people have been struck down by listeriosis after eating soft cheese.

The cases in NSW follow seven cases last week.

They bring the total number of people affected nationwide to 21.

Two Australians have died and a pregnant woman has miscarried following the outbreak.

The people ate cheese produced by the Jindi Cheese Company that has since been recalled.

Tests are still under way to confirm a direct link with the current outbreak, according to NSW Health.

Jindi has voluntarily recalled all batches of cheese manufactured up to and including January 6.

It follows an earlier recall of brie and camembert cheeses on December 19 after the first cases were identified.

Listeria has a 70-day incubation period so new cases could still emerge.

NSW Health acting director of health protection Professor Wayne Smith said all of the recent cases involved people aged over 65 with one person in a serious condition.

"These cases highlight the need for people to check their fridges to see if they have any of the recalled cheeses and discard or return to the place of purchase any cheese that is on the list of recalled products," he said in a statement.

"If the brand or best before date is unknown, do not consume the cheese, rather it should be discarded," he said.

Listeria is a bacteria that can affect a number of food products but particularly soft cheeses including brie and camembert.

The infection may cause minor or no symptoms in healthy individuals but can be particularly dangerous for the elderly, pregnant women and people with compromised immune systems, such as cancer patients.

Early symptoms include fever, headache, tiredness, aches and pains.

Consumers can call the Jindi helpline on 1800 680 175 for more information on the recalled cheeses.