Immunity & Listeria | Strong Immune System Blog

Listeria Tainted Cantaloupes


If you took a course entitled, “How to Avoid Contaminated Food 101,” you’d probably learn that produce that you have to peel is safer than thin-skinned produce like strawberries and plums. But in the 200-level of the course, you would learn that you need to scrub the fruit before peeling it regardless of how think the peel is. The current listeria outbreak coming from tainted cantaloupes provides a case-in-point.

As of this morning, 16 people around the country have died from eating infected cantaloupes and 72 have been sickened.1 The cantaloupes all seem to come from a single producer in Colorado (Jensen Farms), who claims the fruit got distributed to 25 states, including Arkansas, Arizona, California, Colorado, Idaho, Illinois, Kansas, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Virginia, and Wyoming.  And one death has occurred in a state not on that distribution list (Maryland), a fact that has the officials alarmed.

Listeria is a bacteria-borne illness that causes nausea, vomiting, fever, and diarrhea. According to the Centers for Disease Control, it’s more deadly than salmonella or E. coli, with a mortality rate of 16 percent.2 People most vulnerable to the disease include infants, elderly people, and those with compromised immune systems. In this outbreak, the average age of the victims has been 78.3 When young, healthy individuals are exposed to the bacteria, they typically experience only minor symptoms.

Several factors have experts extremely concerned that the epidemic may grow exponentially. First, as previously mentioned, there’s that death in Maryland, which may mean that the affected cantaloupes got shipped to more states than on the list, perhaps by distributors who passed along the fruit to other distributors. Also, the disease has a long incubation period — up to two months. The melons were recalled on September 15. Assuming that the last tainted melon got eaten on September 14, some victims have more than a month to go before they start experiencing symptoms. And then, there may be some who haven’t gotten the news about the deadly fruit and have been storing their cantaloupes. If they dig into the fruit today, assuming it hasn’t yet rotted, they won’t have symptoms until late November. So there’s plenty of time left for more people to contract the disease. Plus, officials worry that some of the fruits lacked labels, so consumers might not recognize them as among the tainted crop.4 And then, as we’ll talk about in a moment, there’s always the possibility, even if people threw the melons out, that the bacteria from the melon’s rind transferred to the vegetable bin and other fruits and vegetables that were in there.

You would think that anyone who hears about the cantaloupe deaths would not now put the fruit on the menu no matter what right, but the director of the Centers for Disease Control, Thomas Frieden, advises, “If it’s not Jensen Farms, it’s OK to eat. But if you’re in doubt, throw it out.” That seems to be rather blasé advice, given the “mystery case” in Maryland. Better advice might be to avoid all cantaloupe and any food that has been in proximity to cantaloupe for the next couple of months unless you’ve grown the melon yourself.

Listeria spreads by way of animals that carry the bacteria to soil and water sources, and by way of workers hands if they’ve been working with dirt or manure. Melons (like pumpkins and squash) are particularly vulnerable because they lie about on the ground (although commercial growers often grow them on plastic sheets for weed control, which offers some protection), unlike fruits or vegetables that grow on trees, vines, i.e. above ground. And cantaloupes, because of all the ridges and grooves on their surface, offer an especially attractive breeding ground for contaminating bacteria. Like a good English muffin, there are plenty of nooks and crannies to hide in. Any surface that comes in contact with the bacteria can be affected, so a contaminated cantaloupe can spread bacteria inside the fridge, onto your counters, or to other foods that it touches. The bacteria also can get on your hands, even if you never eat the cantaloupe. If your finger goes in your mouth after you touch the cantaloupe or a surface it was on, so does the disease. (Think about that person in the supermarket fondling a contaminated cantaloupe and then immediately moving over to the apple bin and sorting through a couple of dozen apples to select six for herself; those remaining apples that you now buy are contaminated.) And while the bacteria lodges on the outside of the cantaloupe skin rather than inside on the flesh, once you cut it with a knife, the bacteria has a nice ride into the fruit’s interior on the knife blade. By the way, most previous outbreaks of listeria haven’t involved fruit or vegetables at all, but have come from dairy products (both pasteurized and unpasteurized) and deli meats where the bacteria got into a processing plant.

Experts advise that in order to avoid getting sick with listeria, you should wash any surface touched by melons with something capable of killing bacteria, such as a bleach solution. In the future, you should make it a habit to wash your hands thoroughly before and after handling any melons.5 Also, you should scrub the outer rind of melons thoroughly under running water, and then rinse in a vinegar, bleach, or hydrogen peroxide solution or a vegetable wash — all of which can kill bacteria. Then let the melon thoroughly dry before cutting it.  And don’t buy bruised fruit. Although listeria can thrive in cold conditions and when exposed to heat, other foodborne illnesses don’t do well at extreme temperatures, and so it’s good to keep produce cold, at 40 degrees or lower. And remember, sometimes washing doesn’t help. Some bacteria, such as E. coli, are capable of traveling with the irrigation water to the “inside” of fruits, vegetables, and sprouts where no amount of washing can get them out.

In fact, some experts say you’re better off scratching cantaloupe from your menu entirely, as the fruit has a rather wicked history of spreading disease. This outbreak is actually the 19th case of cantaloupes causing foodborne illness since 1984. That fact alone points to the tragedy of what our food production system (rife with possibilities for cross contamination as infected produce travels throughout the continent) has become. We now have to consider the possibility, across the developed world, that lurking behind that nutritionally rich fresh food in your supermarket may lurk a killer bacteria. And it’s not just cantaloupes: in case you’ve forgotten, a quick perusal of high-profile incidents involving foods causing widespread sickness shows that plenty of other food items have caused serious problems in the past 10 years — including strawberries, turkey burgers, prepared salad mix, papayas from Mexico, processed meats, eggs, peanut butter, cookie dough, salsa, milk, frozen pot pies, beef, spinach, and green onions.6

Makes you think Joni Mitchell had it right so many years ago when she sang in her song, “Woodstock, “We’ve got to get ourselves back to the garden.” Of course there are no guarantees even on your own little farm, but at least you aren’t at the mercy of dirty processing plants or industrial growing factories that not only periodically distribute disease-bearing food across wide swaths of your country, but also ply you with foods awash in pesticide residues and diminished nutrition.


1 “Listeria-Cantaloupe-Linked Deaths Rise to 16.” 27 September 2011. CBS News. 29 September 2011.

2 Weise, Elizabeth. “Experts issue new warnings in listeria outbreak.” 29 September 2011. USA Today. 29 September 2011. <>

3 Aleccia, JoNelle. “CDC confirms 13 dead in cantaloupe listeria outbreak. 27 September 2011. Food Safety at 29 September 2011. <>

4 “Listeria Outbreak: What are the Main Symptoms?” 29 September 2011. IBT Times. 29 September 2011. <>

5 Marchione, Marilynn. “Cantaloupe crisis lesson: some food should always be avoided.” 29 September 2011.

6 “List of foodborne illness outbreaks in the United States.” Wikipedia. 29 September 2011. <>