Three deaths and three illnesses have been linked to milkshakes contaminated with listeria sold at a Frugals restaurant in Washington, the state Health Department said.

Listeria bacteria was found in all milkshake flavors sold at the Frugals location on Pacific Avenue in Tacoma, officials said Friday. The listeria was found in the ice cream machines, which were improperly cleaned. The restaurant stopped using the ice cream machines on Aug. 8, but listeria can sicken people up to 70 days after being ingested.

Listeria can cause serious and sometimes fatal illness in pregnant people, young children, those over 65 and people with weakened immune systems, according to the Centers for Disease Control and Prevention. Other people can be infected with listeria, but they usually do not become seriously ill, the CDC said.

An estimated 1,600 people get listeriosis each year and around 260 die, according to the CDC.

Healthy people may experience symptoms like high fever, severe headache and stomach pain. The infection can also cause miscarriages and stillbirths. An estimated 1,600 Americans get listeriosis each year, and about 260 die, according to CDC data.

All six people in the Washington case had conditions that made their immune systems less able to fight disease, officials said. 

The state Health Department advised anyone with a weakened immune system to contact their health care provider if they ate a milkshake at the Tacoma Frugals between May 29 and Aug. 7. Frugals has three other locations in Washington and three in Montana, but they do not appear to have been affected, the department said.

Listeria, which generally causes fever, muscle aches and tiredness, can be treated with antibiotics. Other symptoms include headache, a stiff neck, confusion, loss of balance and seizures. 

In a separate ice cream-related listeria outbreak, a frozen food company from New York in early August recalled cups of its 8-ounce ice cream because the product might be contaminated with listeria. Health officials were looking into hospitalizations in New York and in Pennsylvania. The Food and Drug Administration said the Real Kosher brand Soft Serve On The Go ice cream was sold in 19 states and Washington, D.C.