Officials in New Zealand are investigating a Salmonella outbreak that has sickened 35 people so far this year.

Salmonella Enteritidis sequence type 11 (ST 11) was first detected in 2019 in an outbreak traced to a restaurant in the Auckland region. Since May 2019, the number of patients associated with this strain is 101 and from 2019 it has been found in four other outbreaks.

The majority of people sick from January to April this year live in the Auckland region, according to the Institute of Environmental Science and Research (ESR).

New Zealand Food Safety found Salmonella Enteritidis at an Auckland poultry farm and there has been a rise in infections caused by this strain of Salmonella despite attempts to prevent contaminated eggs reaching consumers.

The Ministry for Primary Industries (MPI) has yet to clarify for Food Safety News the sequence type detected at the poultry farm.

Infections linked to Salmonella findings
Paul Dansted, director of food regulation at New Zealand Food Safety, said the cause of infections is being investigated.

“There has been an increase in human cases caused by the same strain of Salmonella found in our investigation, which we are tracking alongside the Ministry of Health,” he said.

“However, to reduce the possibility of getting ill through food, we’d like to remind people to follow the 3Cs of food safety at home. In other words, clean food preparation surfaces, cook raw chicken meat to an internal temperature of 75 degrees C (167 degrees F), and chill cooked chicken meat in the fridge.

“For context, the Salmonella Enteritidis bacterium is present in the poultry industries of many countries and is managed by a variety of regulatory controls. However, it does occasionally cause outbreaks of food poisoning, and can be serious. We continue to monitor the situation with the Ministry of Health and are working closely with the poultry sector to ensure any risk is identified and dealt with.”

Mitigation measures
A New Zealand Food Safety audit and follow-up testing found Salmonella at an Auckland supplier of hatching eggs and day-old chicks to industry.

Dansted said the facility has taken steps to prevent further infection, including sanitizing affected sheds, culling potentially affected chickens, and increased testing.

“These actions, as well as our tracing work, and wider industry testing, have prevented any contaminated eggs from reaching consumers. Our testing and tracing work over the past few months has been focused on ensuring the risk remains low, and to assist industry to eradicate the bacterium from commercial chicken flocks,” he said.

Actions include tracing product from the facility to 64 farms, which have all been tested. Two tested positive and have been required to hold product before it goes to market. Results from 60 farms were negative and findings are pending for two other sites.

Four facilities which earlier tested positive for Salmonella have been sanitized and affected flocks have been culled. Industry has increased testing for Salmonella, above normal requirements, across the supply chain.

Meanwhile, an increase in Salmonella Enteritidis ST183 involving 28 people was identified in February. Sequencing results showed they were genetically clustered which means infection was likely from the same source.

Patients were mainly in the South Island with 18 in Canterbury, four in Nelson Marlborough, three in Capital and Coast, two in South Canterbury and one in Southern. Seven people were hospitalized but no epidemiological link to a common source was identified.

Finally, an outbreak of Clostridium perfringens was reported from the Southern District Health Board in April, involving 27 prisoners at the Otago Corrections Facility. Information on what they had eaten in the incubation period was available for 12 patients and all of them had consumed corned beef.