Health authorities in Australia have closed a catering firm while they investigate the death of a woman who contracted listeriosis.

Officials at the Department of Health and Human Services in the state of Victoria said the confirmed case of listeriosis may be linked to consumption of food supplied to a hospital.

An elderly woman in her 80s who died in an eastern suburbs private hospital on Feb. 4 was diagnosed with listeriosis. I Cook Foods of Dandenong South, a suburb in Melbourne, provides meals to the private hospital.

The commercial caterer was ordered to suspend production while the source of Listeria that caused the woman’s infection is being investigated. The company serves a range of private hospitals, elder care facilities and Meals on Wheels services in the north eastern and south east suburbs of Melbourne, Traralgon and Ballarat.

Testing on food samples collected at I Cook Foods returned six positives for Listeria monocytogenes.

Affected private hospitals, care facilities and Meals on Wheels services were urged to dispose of any foods produced by the caterer between Jan. 13 and Feb. 21 this year. No public hospitals are supplied by the company.

The Department of Health and Human Services and the Greater Dandenong Council closed the facility for a thorough cleaning. It will not reopen until further testing is done and improvements are made. Health authorities are assessing whether changes are required to food handling processes and layout of the premises.

Listeria monocytogenes can be found in many foods including but not limited to raw dairy products; raw and frozen fruits and vegetables; smoked fish and meats; processed meats; and frozen foods such as ice cream and microwave dinners. Cooking to temperatures higher than 65 degrees C kills the bacteria.

Symptoms range from mild flu-like symptoms of fever, chills, muscle aches, nausea and sometimes diarrhea to more serious including meningitis and sepsis. The elderly, pregnant women, newborn infants and people with weak immune systems are more susceptible to infections. The incubation period is usually one to two weeks but can vary between a few days and up to three months.

There have been two cases of listeriosis this year in Victoria compared to nine for the same period in 2018. The state had 27 cases in 2018.