Listeriosis Outbreak in Cantaloupes

2011 Food Factor Robotics

PEGBOTSFLL Team # 7056

The 2011 Listeriosis Outbreak

• The outbreak of Listeriosis in 2011 was one of the worst food poisoning incidents in the US in recent history.

• It resulted in 139 illnesses, 29 deaths and at least one miscarriage.

• It points out the importance of food safety procedures in harvesting, processing, storage, transport and preparation of fresh produce.

Listeriosis: The Basics

• Listeria monocytogenes is the bacterium• The 2011 outbreak is the first outbreak of

listeriosis in cantaloupes. Other outbreaks have occurred in hot dogs, deli meats, and Mexican-style soft cheese.

• One in five people who become ill with listeriosis can die.

• The average age of thoseaffected is 78.

2011 Outbreak: The Basics

• Known to be in cantaloupes.• Previous outbreaks of illnesses from

cantaloupes have been linked to salmonella or a norovirus (an RNA virus), and the bacteria were usually from imported cantaloupes.

• The current outbreak of listeriosis is comparable to deadly outbreaks of e. coli and salmonella.

How It All Started

• The cantaloupes came from Jensen Farms.• Jensen Farms is located in Granada, Colorado.• Jensen Farms bought equipment, previously

used to wash and dry potatoes, in July 2011. The equipment most likely harbored the bacteria before it was bought by Jensen Farms.

• The bacteria probably also formed in the pools of water on the floor of the processing plant.

Listeriosis Symptoms

• Fever• Muscle aches• Diarrhea• Headache• Stiff neck• Confusion• Loss of balance• Convulsions

Who Is Likely to Get Listeriosis?

• Pregnant women – 1 in 6 cases of listeriosis affect pregnant women. However, the infants that are born suffer much more severe symptoms – stillbirth, a life-threatening illness, or other symptoms.

• People with AIDS are 300 times more likely to get listeriosis than people with healthy immune systems.

• Others likely to get listeria: people with cancer, diabetes, alcoholism, weak immune systems, or liver or kidney disease.

• Other people can easily be infected with listeriosis, but the effects will most likely be less severe.

How can a cantaloupe be infected with the listeria bacterium?

• Listeria monocytogenes can form in the ground and in standing water (i.e. ponds, puddles...).

• Some cantaloupes are washed in tanks or with sprays, and cooled off with cold water. As this can make it more likely for the listeriosis bacterium to grow on the cantaloupes, some believe that the cantaloupes should be cooled off with cold air and should not be washed in water.

• The bacteria can grow at temperatures as low as 34°F (1°C). Low storage temperatures slow, but do not stop growth. Freezer temperatures of 0°F will stop it from multiplying, but may not destroy it.

Where does listeria monocytogenes live?

• While living on a cantaloupe, Listeria monocytogenes lives on the rind. The bacterium is spread to the flesh, the part we eat, when the cantaloupe is cut.

• While living inside a human’s body, the bacterium can live practically anywhere. They are mainly found in the brain and spinal cord (and in pregnant women, the placenta, the organ which connects a baby’s umbilical cord to the uterus).

• Surprisingly, they can live in white blood cells called macrophages that are meant to destroy it.

What happens if listeria monocytogenes is in your body?

• Blood or spinal fluid tests will be performed if you think you have listeriosis.

• If you do have listeriosis, it will be treated with antibiotics.

• Some people may eat contaminated cantaloupes, but do not experience symptoms. Doctors say that they do not need to be treated.

• One in twenty (1/20) people carry the bacterium in their intestines. It does not affect them.

Our Solution• Add an organic acid (e.g. lactic, citric or acetic

acid) to the wash water to lower the pH to less than 4.5.

• Dry cantaloupes with air after washing to prevent bacterial growth.

• Store cantaloupes in CO2 to keep the pH low to kill Listeria and also to inhibit aerobic organisms (mold, insects).

• We built a model of a produce washing system.

At Home• Wash the outside of your cantaloupe just before cutting it. Use a vegetable brush.• Make one slice, rinse the cut face to remove bacteria that might be spread from the rind.• Scoop out the insides to serve and throw away the rind and seeds.• Wash the knife, the cutting board and your hands after handling the rind.• Refrigerate the cut cantaloupe if you aren’t going to serve it right away.

•Just before preparing and serving, wash the outside of your cantaloupe in running water.

•Use a vegetable brush to remove dirt and bacteria hiding in the nooks and crannies of the rind.

Our Experiment

We demonstrated how bacteria can be spread from the rind to the flesh of a cantaloupe.We put a line of blue food dye on the rind as a safe surrogate for the bacteria.We cut through the cantaloupe with a sharp knife. These photographs show how far the bacteria can be spread with a single slice of the knife.

Mr. Cantaloupe with blue food dye representing bacterial contamination.

BEFORE

Slicing through the cantaloupe along the line of blue food dye.

DURING

Bacterial contamination can be carried into the flesh of the cantaloupe by the knife.

AFTER

Bibliography

• http://www.nytimes.com/2011/09/29/business/costco-urges-stricter-safety-measures-on-cantaloupes.html

• http://yourlife.usatoday.com/fitness-food/safety/story/2011-09-28/Experts-fear-listeria-may-be-moving-into-produce/50589766/1?csp=ylf

• http://www.cdc.gov/listeria/definition.html• http://www.faqs.org/health/topics/74/Listeriosis.html