What is Listeria caused by? Definition and symptoms explored as Florida outbreak sparks concern

The microscopic representation of the bacteria that causes the infection (Image via CDC)
The microscopic representation of the bacteria that causes the infection (Image via CDC)

On Friday, July 1, the US Centers for Disease Control and Prevention (CDC) released a report which mentioned the recent listeria outbreak in the country. As per the press release, around 23 individuals have been infected from 10 states, with one of them being dead.

The document further reported that almost all of the victims had traveled to Florida within the last month. However, it must be noted that no cause has been determined despite the common connection of all these cases.


In their report, the CDC has urged local healthcare providers to report the cases to their respective health departments. This would give them the dataset required amid the investigation of the sudden cause of this disease.

What did the CDC say about the ongoing Listeria outbreak in the US?

NEW Listeria outbreak: 23 people sick, 20 of them live in or traveled to Florida before they got sick. No food linked to outbreak yet. CDC will provide new info as investigation progresses.

As per the US Centers for Disease Control and Prevention’s press release, around 22 people have been hospitalized over the outbreak, with one fatality in Illinois.

They further mentioned that one pregnant woman suffered a miscarriage over complications from the listeriosis illness. In total, around five pregnant patients have been found to have been affected by the disease so far.

The agency has also advised certain demographics of individuals who are at a higher risk. They said:

“Pregnant people and their newborns, adults aged 65 and older, and people with weakened immune systems are at higher risk for severe Listeria. CDC is advising people at high risk who have symptoms of a Listeria infection, especially those who have recently traveled to Florida, to talk to their healthcare provider.”

In addition, they also revealed that their investigation hasn't been able to identify any food source as the reason behind the outbreak yet.

Listeria symptoms and causes


According to the Mayo Clinic, the infection is often caused by food sources and especially affects those who are older than 65, pregnant or have a compromised immune system. The nonprofit American medical-based academic portal further mentioned:

“Healthy people rarely become ill from listeria infection, but the disease can be fatal to unborn babies, newborns, and people with weakened immune systems. Prompt antibiotic treatment can help curb the effects of listeria infection.”

The infection can have symptoms including fever, nausea, diarrhea, and muscle aches. It can also spread to the nervous system, which has its own symptoms like headaches, confusion, disruption in balance, and may even cause seizures. Meanwhile, it can even affect newborns and may cause difficulty in breathing, vomiting, and loss of appetite.

In regards to the infection, multiple medical publications state that the symptoms may take over 30 days to register. Meanwhile, the CDC report added:

“Symptoms of severe illness usually start within two weeks after eating food contaminated with Listeria but may start as early as the same day or as late as 70 days after.”

What can be the causes of the infection


The species of bacteria that causes the disease is called Listeria monocytogenes and can be present in contaminated water, food, soil, and less commonly ingested things like animal fecal matter.

In the food chain, the bacteria can be present in vegetables or fruits that have been grown with manure made from a carrier animal’s feces. Moreover, the soil growing vegetables may also be contaminated if water sources with the bacteria present make it to the ground table.

Meanwhile, often unpasteurized milk or other dairy products like cheese can cause the infection. In addition, deli meat containing products like sausages, meat jerkies and more can also cause listeriosis.

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Edited by Sijo Samuel Paul
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