Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.See all posts »
Tomatoes and Salmonella
Over the past few weeks, we were informed that now we all needed to be extra careful, because we were supposedly in the midst of a multi-state (U.S.) outbreak of infections caused by Salmonella serotype Saintpaul, attributed to consumption of raw tomatoes, and in particular, red plum, red Roma, or round red tomatoes.
Thirty-two states and the District of Columbia were said to have reported infections to the Centers for Disease Control, via the identification of Salmonella strains from ill persons routed for identification through the State health departments. The reports were presumedly linked to tomatoes - consumed at home or in restaurants. There was no definitive link to tomatoes consumed "in the wild" - and none to my knowledge on an expedition. Now it appears that these Salmonella infections may not have originated with tomatoes after all, but from some unknown carrier(s) of the bacteria. We are not yet even sure if the contaminated food was produce, but that is a possibility. If it was not tomatoes, perhaps it was something served with tomatoes, or a food product made with tomatoes, such as salsa. If it was salsa, then it could have been any of the other ingredients, such as green onions, cilantro, or jalapeño peppers.
If there are contaminated tomatoes, or any other vegetable, meat, or other food product(s) in circulation, sooner or later, someone will get become sick after eating the product during a picnic or an outdoor trip. In retrospect, and for the purpose of avoiding future illness, it is very important to note that we do not have information about how the culprit tomatoes were supposedly handled prior to consumption - were they washed, and if so, in what manner? I don't imagine that we will ever learn these details, particularly if the very origins of the reported illnesses are in doubt.
So, that leads us back to a general discussion of infection with Salmonella, which is a very real cause of diarrheal illness. There are multiple species of Salmonella, including Salmonella typhi, which causes typhoid fever. The bacteria normally reside in the intestinal tracts of humans and other animals, including birds. The most well known causes of Salmonella food poisoning are contaminated beef, poultry, milk, and eggs. Salmonella food poisoning (infection), usually caused by S. typhimurium or S. enteritidis, typically causes diarrhea (loose and watery stools, usually without blood), fever, and abdominal cramping 12 to 72 hours after incubation of the infection. Untreated with an antibiotic, the illness usually lasts from 4 to 7 days. The infection may spread and cause the victim to become seriously ill, or rarely, to die. On occasion, persons with Salmonella infection develop a post-infection syndrome of painful joints, irritated eyes, and pain on urination.
For gastroenteritis, antibiotic therapy is usually not indicated, because it does not shorten the duration of the disease. Furthermore, antimotility drugs, such as loperamide (Imodium), are not recommended, because they may prolong contact time of the bacteria in the bowel, and prolong or worsen the illness. However, antibiotics are often recommended for Salmonella gastroenteritis in infants younger than 3 months, infants younger than 12 months with temperatures higher than 102.2°F (39°C), and persons with certain blood disorders, HIV infection or other cause of immunosuppression (e.g., diabetes or chronic steroid therapy), cancer, or chronic gastrointestinal illness. The recommended antibiotics for such individuals include ampicillin, amoxicillin, trimethoprim-sulfamethoxazole, cefotaxime, ciprofloxacin, and ceftriaxone, among others.
So far, in this current Salmonella outbreak, there have been no directly-attributable deaths reported, but at least 53 persons have been hospitalized. Overall, the number of afflicted persons is likely greater than that reported, because many people who develop diarrhea don't seek medical care and/or obtain a stool culture.
The Food and Drug Administration (FDA) has been advising consumers in the U.S. to be cautious, and to choose for consumption cherry tomatoes, grape tomatoes, tomatoes sold with the vine attached, homegrown tomatoes (more reason to "go organic"), and to avoid red plum, red Roma, and round red tomatoes unless they come from reliable sources. Of course, much as one needs to avoid contaminated ice in beverages, one should be aware that if tomatoes are the culprits, then raw tomatoes used to prepare sauces, salsa, cold soups, and other food products can carry Salmonella. Ditto for lettuce or any raw fruit or vegetable. The truth is that right now, we don't know precisely what to avoid.
Here are additional precautionary measures that place emphasis on food handling and preparation:
1. Within 2 hours of use, refrigerate or discard cut, peeled, or cooked fruits and vegeatables.
2. Do not purchase bruised or damaged fruits or vegetables.
3. Wash all vegetables and fruits thoroughly under running water. If you are camping, use properly disinfected water. Soaking vegetables and fruits with a skin or "peel" in an iodinated disinfecting solution, then rinsing with disinfected water to remove the residual iodine (and improve the taste) is a common practice in some third world restaurants.
4. Keep raw produce for consumption separate from raw meats and seafood.
5. Wash all cutting boards and surfaces, dishes, utensils, and counter tops with soap and hot water in between handling different types of food products.
6. One might consider peeling tomatoes, but there is not yet evidence that this makes a difference in diminishing the number of infections, which may not be caused by the tomatoes anyway.
The U.S. Department of Agriculture has an excellent Fact Sheet entitled "Salmonella Questions and Answers."
In summary, the recent reports of Salmonella infection, while perhaps attributable to tomatoes, may well have been created by an alternative source(s). The rules for safe food handling and avoidance of food-borne infection apply to all foods, not just tomatoes.
image of "Tennessee tomatoes go camping" courtesy of blackstarjewelry's photostream
Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.
Tags: tomato, Salmonella, disinfection, wilderness medicine, outdoor medicine, healthline
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