What you need to know about Listeria monocytogenes
September 28th, 2011
12:35 PM ET

What you need to know about Listeria monocytogenes

With an outbreak of sickness linked to  bacteria-tainted cantaloupe now reported in more than a dozen states, here's a quick backgrounder on listeria monocytogenes.

What is it?
Listeria monocytogenes is a “hardy” bacterium that is resistant to extreme hot and cold. This bacterium is pathogenic – meaning that it is infectious to humans, causing the illness listeriosis.

Where does it come from?
Listeria is found in soil, water and the intestines of some animals. Unfortunately, most animals show no symptoms so the bacterium is transferred to raw foods such as unpasteurized dairy products, raw vegetables and raw meats. And unlike similar types of bacteria, listeria can grow in the low temperatures of a refrigerator.

Studies also suggest that up to 10% of humans may be carriers. The FDA says that when listeria gets into a factory environment it can live for several years.

But how did it get inside of cantaloupes?
Cantaloupes and other fruits with porous surfaces can become infected by listeria when soil and/or water seeps through their skin. Any bacterium that remains on the outside can be transferred from the shell to the inside when the fruit is sliced open by a knife or handled.

Who is most at risk?
Listeriosis primarily affects the elderly, pregnant women, newborns, and people with weakened immune systems. In the U.S., an estimated 1,600 people become seriously ill each year; approximately 16% of these illnesses result in death. Cervical infections caused by listeriosis in pregnant women may result in spontaneous abortion during the second or third trimesters or stillbirth.

What are the symptoms of listeriosis?
The early symptoms of listeriosis are similar to those of the flu with nausea, muscle aches and a high fever. Gastrointestinal symptoms such as diarrhea may also appear. The length of time between infection and the appearance of symptoms is unknown.

How can I protect myself?
Recommendations for keeping food safe from listeria are similar to those used to protect against other foodborne illnesses. Remember to cook meat to the USDA’s recommended temperatures and to wash all raw vegetables and fruit. Keep your fridge below 40 degrees Fahrenheit and eat leftovers within three to four days, the CDC says.

I’ve eaten a cantaloupe! What should I do?
Your risk of developing listeriosis is extremely low, even if the cantaloupe you ate was contaminated. If you do not have any symptoms you’re most likely in the clear. However, if you’re in one of the high risk groups and showed symptoms up to two months after eating a possibly contaminated product, contact your doctor.

Has this happened before?
About 800 cases of Listeria infection are diagnosed each year in the United States, along with three or four outbreaks of Listeria-associated foodborne illness. A multi-state outbreak of listeria from contaminated hot dogs and deli meats occurred in 1998, killing 21. Between 1998 and June 2009, 48 deaths from listeria-caused illnesses were reported by the CDC’s Foodborne Outbreak Online Database.

Got a question about the outbreak? Ask it below and we’ll do our best to find an answer.

To learn more visit the FDA's Bad Bug Book or the CDC's section on listeriosis.

soundoff (4,155 Responses)
  1. Kevinfeems

    generic aralen order chloroquine phosphate – chloroquine tablet price
    http://amoxicillintop.com/# buy amoxicillin from canada

    June 22, 2021 at 12:35 | Report abuse | Reply
  2. RV Exhaust Repair Near Me

    Oh my goodness! Amazing article dude! Thank you so much, However I am having issues with your RSS. I donít understand why I am unable to subscribe to it. Is there anyone else having similar RSS issues? Anyone that knows the answer can you kindly respond? Thanks!!


    June 22, 2021 at 12:52 | Report abuse | Reply
  3. RV Roof Repair Service Near Me

    Hi there! I could have sworn Iíve been to this site before but after browsing through some of the posts I realized itís new to me. Nonetheless, Iím definitely pleased I stumbled upon it and Iíll be bookmarking it and checking back frequently!


    June 22, 2021 at 14:24 | Report abuse | Reply
  4. Jerrylen

    buy doxycycline cheap doxycycline – 200 mg doxycycline
    http://chloroquinetop.com/# chloroquine for sale
    neurontin uk neurontin without prescription gabapentin 300

    June 22, 2021 at 14:58 | Report abuse | Reply
  5. Kevinfeems

    buy chloroquine chloroquine – chloroquine for sale
    http://doxycyclinetop.com/# doxycycline prices

    June 22, 2021 at 15:08 | Report abuse | Reply
  6. Alternator Mercedes Sprinter 2016 Repair

    I absolutely love your blog.. Pleasant colors & theme. Did you build this amazing site yourself? Please reply back as Iím hoping to create my own site and want to learn where you got this from or just what the theme is called. Thank you!


    June 22, 2021 at 16:22 | Report abuse | Reply
  7. Jerrylen

    amoxicillin 500mg capsule buy online purchase amoxicillin online – where can you get amoxicillin
    https://amoxicillintop.com/# where to buy amoxicillin over the counter
    how to order doxycycline generic doxycycline doxycycline pills

    June 22, 2021 at 17:34 | Report abuse | Reply
  8. Kevinfeems

    buy doxycycline online buy doxycycline online – buy doxycycline online uk
    https://amoxicillintop.com/# amoxicillin over counter

    June 22, 2021 at 17:39 | Report abuse | Reply
  9. SEO Marketing Service

    An outstanding share! I've just forwarded this onto a colleague who was doing a little research on this. And he in fact bought me dinner simply because I stumbled upon it for him... lol. So let me reword this.... Thanks for the meal!! But yeah, thanks for spending time to talk about this matter here on your web site.


    June 22, 2021 at 18:33 | Report abuse | Reply
  10. Internet Marketing Experts Near Me


    June 22, 2021 at 18:34 | Report abuse | Reply
  11. RV Awning Repair Near Me

    I blog often and I really thank you for your information. This great article has really peaked my interest. I will book mark your site and keep checking for new details about once per week. I subscribed to your Feed as well.


    June 22, 2021 at 19:26 | Report abuse | Reply
  12. Kevinfeems

    where to buy amoxicillin 500mg buy amoxicillin – 875 mg amoxicillin cost
    https://neurontintop.com/# neurontin cap 300mg

    June 22, 2021 at 20:07 | Report abuse | Reply
  13. Jerrylen

    order doxycycline buy doxycycline – doxycycline mono
    http://neurontintop.com/# neurontin 100 mg tablets
    amoxicillin cost australia buy amoxicillin where to buy amoxicillin over the counter

    June 22, 2021 at 20:07 | Report abuse | Reply
  14. Video Marketing Services


    June 22, 2021 at 20:29 | Report abuse | Reply
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83

Leave a Reply to Richardder


CNN welcomes a lively and courteous discussion as long as you follow the Rules of Conduct set forth in our Terms of Service. Comments are not pre-screened before they post. You agree that anything you post may be used, along with your name and profile picture, in accordance with our Privacy Policy and the license you have granted pursuant to our Terms of Service.

About this blog

Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.