Common Causes of Food borne Illnesses

The Centers for Disease Control (CDC) in Atlanta, GA estimates that there are about 48 million illnesses caused by food borne bacteria each year. As many of you know, the incidence of outbreaks of Salmonella gastroenteritis is growing steadily and it seems that a week can’t go by without a report of a new outbreak. For those of you who are so inclined, the CDC publishes a weekly report entitled Morbidity and Mortality which tracks and reports the incidence of infectious diseases in the US. 

Interestingly, most food borne disease outbreaks primarily result from improperly handling, storing, transporting or preparing of raw food stuffs and consequently are easily preventable. To that end, the folks at Nursing Schools.net sent me a link to a post on their website that describes ways in which to better manage raw foods that can help to prevent or minimize the incidence of food borne illnesses in the US. An excerpt of the post is shown below.

The 12 Most Common Causes of Food Poisoning

**It is important to point out that the term “food poisoning” is anachronistic because in the past, it was not clear what was responsible for the illnesses caused by tainted food. While not currently used much in food microbiology circles, food poisoning (or intoxication) was historically used to describe ingestion of food that contained bacterial toxins but no living bacteria and caused disease. Staphylococcal “food poisoning” is the most common type of food intoxication that causes disease. In contrast, food borne illness is used to describe disease caused by ingestion of contaminated food containing live bacteria which subsequently colonize the lower gastrointestinal tract, invade the intestinal mucosa and thereby cause disease.**

Raw or undercooked food. Whether you're cooking at home or going out, eating food that hasn't been cooked thoroughly or brought to the appropriate temperature can put you at high risk of developing food poisoning. While you might enjoy rare steak, runny eggs or certain raw veggies, these foods can all carry bacteria when they are not cooked long enough or hot enough to kill off the offending particles. Common bacteria found in undercooked food include Escherichia coli, Salmonella and Campylobacter. Be safe instead of sorry and ask that your food be cooked through or use this chart when at home.

Food that is not stored at the proper temperature. While simple common sense would tell you that leaving foods like meat and dairy products out of refrigeration makes them unfit to eat, temperature regulation can be a bit more complicated. Refrigerators can malfunction, foods can be forgotten on the counter and instructions on labels can be misread. To keep yourself safe, always check the temperature on your fridge and freezer. They should be at 40 degrees F and zero (0) degrees F respectively. Always read the label to see what foods will need be refrigerated immediately and which have to be cooled after opening. If you plan to freeze foods, do it within 2 days of purchase. This can help prevent some very serious bacteria from growing and making you sick.

Letting food sit out. Most of us are smart enough to not let refrigerated foods sit out, but sometimes we can forget to put away the leftovers or want it on hand at a party. In order to keep these foods safe to eat and avoid some common bacteria taking hold, you should always put leftovers away as soon as you can. If you're serving food at a party, keep hot food at 140 degrees F or warmer, cold foods at 40 degrees F. Never leave perishable food out for more than two hours, especially if the weather is warm. This will help ensure that neither you nor your guests end up sick.

Not washing hands before eating or preparing food. Contamination of foods from dirty hands is a big cause of many cases of food poisoning. Always wash your hands thoroughly before and after handling foods at home (for at least 20 seconds) and only eat at restaurants with strong showings in health department assessments. Additionally, always make sure your hands are clean before eating food as well, especially if you will be touching them. Without these precautions, you could put yourself at risk of coming in contact with bacteria like staphylococcus-aureus and Clostridium perfringens.

Contamination of other foods by raw meat. Cross-contamination of foods is a major health issue and one that many out there should be highly conscious of avoiding at home. When juices from contaminated meat get onto cutting boards, hands and into the refrigerator, contamination can spread to other foods, some of which you might not plan to cook at all. It is essential to keep raw meat, poultry and fish separate from other foods. Always wash any utensils, countertops and cutting boards that have come in contact with them immediately, sanitizing them with bleach and water, or even having separate tools for handling meat can be a big help.

Eating raw shellfish. Raw oysters may be a delicacy, but ingesting them doesn't come without some serious risks. Oysters from the Gulf of Mexico are commonly contaminated with Vibrio vulnificus bacteria which can cause mild to serious food poisoning. Additionally, even oysters that do not come from this region are often left un-refrigerated for several hours while being brought to shore. While you may be fine after eating raw oysters, be aware that ingestion of these shellfish uncooked is a big risk and could lead to serious health issues.

Improper canning. Canning foods at home has been a common practice for several decades, but it's one that needs to be carefully monitored in order to ensure that the food being preserved won't carry contaminates along with it. Botulism is perhaps the most common bacteria contaminant in improperly canned food, and is one of the most serious and potentially deadly forms of food poisoning out there. Always boil jars and lids to be used in canning to kill off any lingering bacteria and make sure that all cans are properly sealed. Improper canning can also happen with foods you get off grocery store shelves so look out for bulges, discolored food, or seepage.

Ingesting expired food. We've all done it at one point or another, but eating expired food comes with a big risk for food poisoning attached. Always check expiration dates before ingesting any food in your home or purchased at the store. If there is no date on the package, no packaging or only a sell by date, use the government guidelines for cold storage to help you determine if a food is safe to eat or not.

Not heating or reheating thoroughly. You might think that you only have to worry about food poisoning in foods that haven't already been cooked, but that's not entirely the case. You should also be careful with foods that you're reheating, especially if they've been hanging out in your fridge for more than a couple of days. When reheating foods, make sure that meats reach a temp of at least 160-170 degrees F and that other foods come to around 165 degrees F. This will ensure that any bacteria that might have made its way into the food will be killed off and that you'll be able to avoid a common cause of food poisoning.

Not washing produce thoroughly before preparation. Even those seemingly innocuous veggies can be the source of food poisoning if not washed and prepared properly. Prior to reaching your table, there's no telling how many things they may have come in contact with, so always clean any fruit or vegetables with a soft kitchen brush and water (or a pre-prepared veggie wash) to ensure that any bacteria it contains will be largely washed away. This is especially important with foods that you do not plan to cook. While foodborne illness is more commonly caused by meats, recent outbreaks of Salmonella and E. coli have originated in spinach and tomatoes.

Unclean cooking utensils and surfaces. When it comes to food safety, cleanliness matters. Dirty kitchens attract mice and rats that can spread disease and also create ideal places for bacteria to grow and thrive and access your food. It's essential to keep any space you plan to cook in and any tools you plan to use highly sanitized. The USDA advises putting a tablespoon of bleach into one gallon of water to create a sanitizing liquid. This can help prevent any bacteria hanging out in your kitchen from getting on food and will ensure that none are able to cross contaminate one another.

Unpasteurized foods. For the most part, people are fine after eating foods that are unpasteurized, provided they have been stored and served in a safe manner. Yet for those with compromised immune systems, who are pregnant and the very young and very old could be at risk for food poisoning from these. Commonly pasteurized foods include milk, cheeses, yogurt, ice cream, ciders and juices. Unpasteurized versions of these foods can carry Salmonella, E coli, and Listeria monocytogenes, which can make individuals very sick

While these precautionary and preventative tactics will help to reduce food borne illnesses, it will not eliminate them completely. But, it is a good place to start to improve food safety and public health!

Until next time...

Good Luck and Good Job Hunting!!!!!!

 

TWiM Episode 4: Cantaloupes and Salmonella Gastroenteritis

On episode #4 of the podcast This Week in Microbiology, Vincent, Cliff, Margaret, and Michael review foodborne bacterial illness in the context of outbreaks associated with cantaloupes and Lebanon bologna.

Right click to download TWiM #4 (51 MB .mp3, 75 minutes).

 

Links for this episode:

Subscribe to TWiM (free) on iTunesZune Marketplace, via RSS feed, by email or listen on your mobile device with the Microbeworld app.

 

 

Salmonella, Turtles and Frogs...Oh My!

As many BioJobBlog readers may know by now, my PhD thesis focused on elucidating the underlying pathogenic mechanisms that contributed to the pathogenesis of Salmonella gastroenteritis. Salmonella gastroenteritis, which is primarily a food-borne illness, occurs in approximately 1.4 million Americans each year. Most people who develop Salmonella gastroenteritis recover without treatment within four to seven days. However, some people develop diarrhea so severe they are hospitalized and can become critically ill. According to a former lab mate, who accidentally infected himself, Salmonella gastroenteritis is much worse than the mild form of the disease described in many microbiology textbooks!

While I haven’t performed any research in this field for about 30 years, I still consider myself to be a Salmonella expert (go figure). Therefore, it should come as no surprise that a newspaper article entitled “Salmonella outbreak linked to pet frogs”— that appeared in the Salt Lake Tribune several weeks ago—caught my eye.

According to the article, a 31-state Salmonella outbreak (which was first detected in Utah was linked to pet frogs. The U.S. Centers for Disease Control and Prevention (CDC) in Atlanta started a national investigation to find the source of the outbreak this past summer, after five Utahans were infected by the strain of S. typhimurium a common cause of gastroenteritis (I knew getting a PhD would useful one day). In all, 85 people across several states developed gastroenteritis and nearly two-thirds had had some contact with frogs. Most of the patients were children and among those whose outcomes are known, almost a third required hospitalization. None died.

The source of the outbreak was eventually linked back to a single frog breeder in California that distributed the African dwarf frogs thought to be responsible for the multi-state outbreak. According to CDC officials, the bacteria were likely spread through contact with the tanks' water, not the frogs themselves. Of those who supplied information to the CDC, 30 percent said they cleaned the frog's aquarium in the kitchen sink and 35 percent used the bathroom basin.

While this last bit of information wasn’t remarkable, I finally—after almost 30 years as card carrying microbiologist—realized how the urban legend about Salmonella and turtles got started! Like many kids, I had a pet turtle. I remember my parents cautioning me about handling the turtle because I would get sick (of course I handled the turtle and never got sick). Later on, as a microbiology undergraduate student, I learned about the relationship between Salmonella and turtles and that turtle had been associated with Salmonella gastroenteritis outbreaks in the past. An interesting but inconsequential fact because I no longer owned a pet turtle.

Early on as a graduate student, I learned that it takes a minimum of about 108 salmonellae to cause gastroenteritis. At the time, I wasn’t thinking much about turtles and failed to realize that the large dose required for infection pretty much ruled out the likelihood that picking up a turtle would almost certainly result in Salmonella gastroenteritis. Although reptiles and amphibians harbor Salmonella in their gastrointestinal tracts, a child would have to suck on an infected turtle (or eat its poop) to get a large enough inoculum to initiate an infection—now this is where the PhD training become evident. However, if parents clean their children’s infected tanks in kitchen or bathroom sinks and then fail to wash their hands or the sinks with disinfectant, the number of salmonellae present in these environments would be sufficient to cause disease if infected food or water was ingested. And, this is what likely happened in the frog outbreak; based on the epidemiological data presented by CDC investigators

So, what is the lesson of this story? While it is true that turtles and frogs may carry Salmonella (in a separate study 21 percent of frogs from 16 retailers tested positive) the likelihood of developing gastroenteritis after touching or briefly handling frogs or turtles is extremely low. However, it is not a good idea to handle them for long periods of time without washing your hands before your next meal or cleaning their tanks in areas where food is prepared or people brush their teeth! Food borne illnesses are easy to prevent if appropriate personal hygiene is practiced and foods are prepared and cooked according to recommended standards. 

Finally, it took a long time, but I can now feel comfortable around turtles. This is probably a good thing—my friend Pete is a turtle fanatic and he constantly wants me to pick up his pets!

Until next time...

Good Luck and Good Job Hunting!!!!!!!!!!

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The Importance of Digital Communications During Infectious Diseases Oubreaks

As we all know, the H1NI pandemic has been raging on for close too 10 ten days now. Curiously, “Fear & The Flu: The New Age of Pandemics” is the title this week’s cover story in Newsweek magazine. From an informational standpoint point, “this may be too little, too late”—as the old saying goes. While the Internet has been around for over twenty years now, government agencies, most notably the US Food and Drug Administration (FDA) and the Centers for Disease Control (CDC) continue to rely almost exclusively on old media to communicate with the American public during infectious disease outbreaks. Apparently, the administrators who run these government agencies haven’t been listening closely enough to President Obama’s assertion that “we live in the digital age.”

Communications between the public and government health officials is vital when trying to manage and control infectious disease outbreaks. “Every single government agency as well as companies and non-profits need to be digitally literate and competent in a time of pandemic” asserts Eye on FDA blogger Mark Senak. For their performances in recent infectious disease outbreaks, Mark gives CDC an “A” for effort—although there is substantial room for improvement. FDA on the other hand didn’t fair as well. “The FDA is not nearly as sophisticated in terms of digital. Their only Twitter account is for food recalls.  And their YouTube channels are all confusing and unorganized. They have a long way to go.”

The Internet was originally designed as a digital tool to transmit and move large amounts of information from one place to another. That said, it is also a powerful communication vehicle that can be used to broadcast valuable, scientifically-accurate information during infectious disease outbreaks by leveraging social media tools like Twitter, Facebook and instant messaging. To that end, it’s time for public health agencies to recognize the power of digital media and craft communication plans that can be implemented in the next infectious disease outbreak.

Until next time...

Good Luck and Good Job Hunting!!!!!!

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A New Year and Another Salmonella Food Poisoning Outbreak

Salmonella enteriditis, an organism dear to my heart (luckily not my posterior small intestine) is a common cause of food poisoning. As some of you may know, I did my PhD thesis work on Salmonella gastroenteritis (aka food poisoning) and I like to think that I am something of an expert on the topic. 

Typically, Salmonella food poisoning outbreaks are localized and rarely reach epidemic proportions. However, there have recently been two major nationwide Salmonella outbreaks in the US —one in 2007 and now in early 2009.

The current outbreak has afflicted 388 people in 42 states and may be caused by the same strain (Saint Paul) that was responsible for the 2007 outbreak. Ultimately, the 2007 outbreak was linked to contaminated tomatoes. The jury is still out on the cause of the most recent outbreak. Needless to say, CDC scientists are scurrying to quickly identify the source of the current outbreak because it took the agency over 5 months to conclusively identify the culprit in the 2007 epidemic. Not surprisingly, many grocery stores and restaurants suffered financially because of the outbreak.

Many of you may be wondering why Salmonella food poisoning is becoming such a problem in the US. I don’t believe that the strains responsible for the most recent outbreaks are more virulent than the ones that have traditionally caused more localized outbreaks. Instead, the reliance of food manufacturers and grocery store chains on one or two major food distributors (rather than multiple suppliers) is likely responsible for the severity and breadth of these nationwide outbreaks. This suggests that regulatory agencies ought to more closely scrutinize the microbiological quality of the operations of the major distributors. I believe that those efforts would greatly reduce the likelihood of future major outbreaks of food poisoning.

Until next time.


Good Luck and Good Job Hunting (avoid raw vegetables, undercooked poultry and raw eggs)
 

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Princeton U Salmonella Outbreak Revisited

I apparently made a few errors in the post about the recent Salmonella food poisoning outbreak at PU (pun intended). I want to thank the anonymous member of the Princeton Graduating Class of ’09 for pointing out the inconsistencies and errors in the post.  First, the so-called “dining clubs” are actually called eating clubs. Second, fraternities and sororities are allowed at PU and I hear that they are alive and well. Finally, I inadvertently noted that the University has severed contracts with several of its produce suppliers which may have been the putative source(s) of the outbreak. In fact, the University didn’t cancel contracts but only temporarily closed a few of the eating stations at the Frist Campus Center. My local newspaper reported that contracts where severed–I guess you truly can’t believe everything that you read!

I was duly chastised for not adequately verifying my information before I hastily crafted the post. I stand corrected and will attempt to be more vigilant in the future. That said, I think that my lack of understanding of the practices and customs at Princeton University is directly related to the fact that I attended Cornell as an undergraduate. Mea Culpa!

Until next time…

Good Luck and Good Job Hunting!!!!!

Salmonella Outbreak at Princeton University--Oh My!!!

Yes, even the Ivy League isn’t immune to food poisoning outbreaks from time-to-time. There are currently 10 confirmed cases of Salmonella food poisoning at Princeton U. Another 50 people or so have also fallen ill with gastrointestinal symptoms consistent with Salmonella food poisoning.  As a precaution, university officials have temporarily discontinued doing business with their produce suppliers. For those of you who don’t know, Princeton is famous (infamous?) for its so-called dining clubs. These clubs take the place of sororities and fraternities which are not allowed at this august institution of higher education. Obviously, there is more than eating that goes on at these “dining clubs.”

The reason I am blogging about the outbreak is two-fold. First, I live about seven miles from Princeton and it has been all over the local news. Second, I did my PhD work on the pathogenesis of Salmonella gastroenteritis. So, Salmonella food poisoning is dear to my heart (thankfully, not my gastrointestinal tract). Many infectious disease experts tend to dismiss the seriousness of Salmonella gastroenteritis. This is likely because it is usually not as devastating as shigellosis or infections caused by enteroinvasive strains of Escherichia coli (which is actually Shigella masquerading as E. coli). As my major professor once put it “You know when you have Salmonella gastroenteritis—if you can’t decide than it is not salmonellosis.”

I am happy to report that I never came down with gastroenteritis while working for over three years with enteroinvasive Salmonella strains (even though I was routinely mouth pipetting and eating lunch in the lab; practices which aren’t acceptable by today’s standards). I like to think that “the bugs” were afraid of me. Alternatively I had either a great immune system or extremely good aseptic techniques. Whatever the reason, it is always embarrassing when card-carrying microbiologists come down with the disease(s) that they are studying. Luckily, I never came down with the disease caused by the bacterium that I was studying during my first postdoctoral fellowship—Neisseria gonorrhoeae. That would have been extremely difficult to explain!

Until next time…

Good Luck and Good Job Hunting (remember to wash your hands)!!!!!!!!