A deadly Listeria outbreak from deli meat and cheese has ended, according to federal officials. 

The notice this week from the Centers for Disease Control and Prevention was the first update from the agency in more than four months. A total of 16 people in six states were confirmed as outbreak patients.

Sick people’s samples were collected from April 17, 2021, to Sept. 29, 2022. 

“The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not have been limited to the states with known illnesses,” according to the CDC. “This is because some people recover without medical care and are not tested for Listeria.”

A single deli or food source was not identified in this outbreak.

Of 14 people who gave information about their illnesses to officials, 13 were hospitalized. One death was reported from Maryland, and there was one pregnancy loss. Thirteen people were hospitalized because they were so ill.

Of 12 people interviewed, 11 said they ate meat or cheese from deli counters. Among seven people who live in New York, five bought sliced deli meat or cheese from at least one location of NetCost Market. Sick people in other states bought deli meats or cheeses from other delis.

“NetCost Market delis are unlikely to be the only source of illnesses because some sick people in the outbreak did not shop at a NetCost Market. A contaminated food likely introduced the outbreak strain of Listeria into delis in multiple states,” according to the CDC update.

The case count by state is: California (1), Illinois (2), Maryland (3), Massachusetts (2), New Jersey (1), and New York (7). This case count has not changed since the outbreak was first announced on Nov. 9, 2022. The patient age range is from 38 to 92 years.

Whole genome sequencing showed that patient samples were closely related genetically, which means they likely got sick from eating the same food. 

In 2021, officials in New York found the outbreak strain of Listeria monocytogenes in environmental samples from a NetCost Market deli in Brooklyn, several opened packages of mortadella and ham that were sliced at that same deli, and in sliced salami that a patient bought from a NetCost Market deli on Staten Island.

NetCost Market owners voluntarily closed the deli temporarily in Brooklyn after they were notified about the sampling results. NetCost Market performed a deep cleaning and then reopened the deli in Brooklyn after further environmental testing did not  find Listeria.

In September 2022, the outbreak strain was found at the same Brooklyn NetCost Market deli; however, the most recent illness with NetCost Market exposure was in October 2021. After a deep cleaning, additional environmental testing did not find Listeria in the deli.

About Listeria infections
Food contaminated with Listeria monocytogenes may not look or smell spoiled but can still cause serious and sometimes life-threatening infections. The bacteria is not killed by freezing temperatures and can thrive in deli counter coolers and on slicing equipment.

It can take up to 70 days after exposure to Listeria for symptoms of listeriosis to develop. 

Symptoms of Listeria infection can include vomiting, nausea, persistent fever, muscle aches, severe headache, and neck stiffness. Specific laboratory tests are required to diagnose Listeria infections, which can mimic other illnesses. 

Pregnant women, the elderly, young children, and people such as cancer patients who have weakened immune systems are particularly at risk of serious illnesses, life-threatening infections, and other complications. Although infected pregnant women may experience only mild, flu-like symptoms, their infections can lead to premature delivery, infection of the newborn, or even stillbirth.

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