Foodborne Illnesses and Ways to Prevent Getting One

Various outbreaks of foodborne illnesses have been making headlines recently. In fact, there’s an outbreak of what appears to be norovirus going on at Yosemite right now. Indeed, it does seem that these incidents are on the rise. Part of it is because of better detection methods. But environmental factors, such as rising temperatures, and food movements, like the increased demand for fresh foods (no “kill step” like cooking or canning), are also contributing factors. At the moment, about a sixth of the US population gets some kind of foodborne illness every year. However, the problem is mostly preventable. These are the most common foodborne illnesses and things you can do to help prevent getting one.

Common Causes of Foodborne Illnesses

Most foodborne illnesses are caused by bacteria and viruses. The others are caused by parasites or toxins produced by organisms. Here are the ones you’re most likely to hear about or encounter:

Bacteria

Bacillus cereus

There are two variations of B. cereus food poisoning. The first causes nausea and vomiting. You typically get it by eating a rice dish that wasn’t cooked enough to kill all the bacteria and then stored for a while at around room temperature. This results in B. cereus multiplying and producing a toxin (cereulide) which causes the symptoms. They start happening about 1-5 hours after eating food containing the bacteria and last for about 1-2 days. Since the toxin is relatively heat-resistant, later reheating of the food won’t help.

The second kind causes abdominal cramps and watery diarrhea. Here, the B. cereus from food that was poorly cooked/stored multiplies in the small intestine and produces a different toxin. The symptoms start happening about 10-16 hours after eating contaminated food and last for about 1-2 days.

Campylobacter jejuni

This bacteria causes fever, abdominal cramps, vomiting, and diarrhea (possibly bloody). The symptoms start appearing 2-5 days after eating contaminated food and last 2-10 days. You mainly get it from handling raw poultry or eating undercooked poultry. But you can also get it from anything that came into contact with an infected animal such as untreated water and unpasteurized dairy. C. jejuni has low tolerance to heat and temperatures above 48 °C (114 °F) will eliminate it completely.

Clostridium botulinum

This is the bacteria that produces botulinum, one of the deadliest toxins we know of. Eating foods containing the bacteria (or the toxin) leads to botulism. The symptoms are nausea, vomiting, abdominal cramps, and things related to decreased muscle function (like blurred vision, difficulty breathing, and slurred speech). Particularly serious cases can lead to respiratory failure and death. The symptoms start appearing about 12-72 hours after ingestion. How long they last depends on the amount of toxin in your system.

C. botulinum is only able to produce botulinum in airless environments, so you mainly get it from improperly canned, preserved, or fermented foods. A bulging can (from gas produced by bacterial growth) is a sign that you should absolutely not eat whatever’s inside it.

C. botulinum is pretty much everywhere and requires very high heat to kill off. But it can’t deal with high-acid or high-sugar environments too well. That’s why the canned foods most commonly affected are low-acid vegetables like green beans. It’s also the reason why you shouldn’t give infants honey or other liquid sweeteners. An infant’s digestive tract will dilute the solution, and a baby’s digestive tract isn’t acidic enough to kill the bacteria. So, it’s possible that they can start growing and producing botulinum.

Clostridium perfringens

Compared to C. botulinum, C. perfringens is much tamer. It typically causes only stomach cramps and diarrhea. The symptoms start happening about 6-24 hours after eating contaminated food and usually last under a day. In some severe cases, though, they can last 1-2 weeks.

The bacteria (in spore form) can’t grow in hot (over 60 °C or 140 °F) or cold temperatures (under 4 °C or 40 °F). In addition, the toxin it produces gets destroyed at temperatures above 74 °C (165 °F). As a result, you really only get it from foods that have been sitting at near room temperature for too long or weren’t cooked or refrigerated properly.

Escherichia coli

This is the same E. coli that just about everyone is familiar with. Most strains harmlessly live in the intestines of warm-blooded organisms (including you), but a few can cause foodborne illnesses. The typical E. coli infection causes abdominal cramps, diarrhea, and sometimes vomiting. The symptoms start happening about 1-3 days after eating contaminated food and last anywhere from 3 days to more than a week.

Heat reliably kills E. coli, so you get it mostly from undercooked foods (especially ground beef), unpasteurized milk or juice (and products made from them), raw fruits and vegetables, and anything contaminated by the feces of an infected organism.

One strain of E. coli, E. coli O157:H7, is particularly harmful. It produces a toxin (Shiga toxin) that causes bleeding in the intestines, leading to much more severe symptoms and bloody diarrhea. A slight fever may or may not accompany the symptoms. Serious cases can lead to kidney failure and even death. The symptoms also last longer than typical E. coli infections.

Listeria monocytogenes

In the milder version of infection, this bacteria causes fever, nausea, and diarrhea like many other foodborne illnesses. This version is not very common. But if the bacterial infection progresses and moves out of the gut, it can cause flu-like symptoms and meningitis (inflammation of the protective membranes around the brain and spinal cord). This can lead to a stiff neck, confusion, loss of balance, fever, muscle aches, and convulsions. In pregnant women, it can cause numerous complications with the fetus (many of them fatal to the fetus). The symptoms take anywhere from a week to several weeks to appear (depending on type of infection).

You get Listeria mainly from unpasteurized milk and products made from it (or contaminated by it) like soft cheeses (ex. queso fresco, feta, Brie, Campbert), raw fruits and vegetables (especially melons and sprouts), deli meats and hot dogs, and refrigerated meat spreads and smoked seafood. Pregnant women, the very young or elderly, and people with weak immune systems are especially susceptible to infection so they should avoid these foods.

Salmonella

A Salmonella infection causes fever, abdominal cramps, diarrhea, and vomiting. The symptoms can appear as little as 6 hours or as long as 2 days after eating food containing the bacteria. They usually last less than a week.

You usually get Salmonella from contaminated eggs, meats, nuts, and raw fruits and vegetables; unpasteurized milk and juices and products made from them; and anything contaminated by the feces of an infected organism. Thoroughly cooking food will kill Salmonella.

Shigella

This bacteria causes fever, nausea, vomiting, abdominal cramps, and diarrhea. In more serious cases, the diarrhea could contain blood and mucus (dysentery). The symptoms start appearing about 1-7 days after ingestion and last less than a week.

It’s very easy for Shigella to spread from person to person. In most cases, you get it from being in contact with an infected person or from eating something that a infected food handler prepared. Thorough cooking will kill the bacteria.

Staphylococcus aureus

You may know this bacteria as Staph. The toxin it produces causes a sudden onset of nausea, vomiting, abdominal cramps, and diarrhea. The symptoms can start happening as little as 30 minutes after ingestion and typically last less than a day. However, sometimes they might take as long as 2 days to go away.

S. aureus normally lives on the skin, so it gets into food mainly because of poor hand hygiene. It grows at temperatures between 60 °C (140 °F) and 4 °C (40 °F). As a result, you normally get it from eating contaminated food that was left at an improper temperature for too long. It’s also worth noting that the toxin it produces when it grows can be present in dangerous quantities in food that doesn’t look, smell, or taste any different than normal.

Vibrio

There are two species of Vibrio that cause foodborne illnesses: V. parahaemolyticus and V. vulnificus. Both mainly come from eating raw or undercooked shellfish, especially oysters. Of the two, V. parahaemolyticus is much less dangerous. It causes nausea, vomiting, abdominal cramps, diarrhea that may or may not have blood, and sometimes fever. The symptoms start happening around 4-30 hours after ingestion and last for about 3 days. However, they can last longer for people with weak immune systems.

In addition to the symptoms V. parahaemolyticus causes, V. vulnificus can also spread into the bloodstream and cause sudden chills, skin lesions, and septic shock. Severe infections can be fatal. Those most at risk are people with weak immune systems, especially people with chronic liver disease.

Yersinia

This bacteria causes abdominal cramps, fever, and diarrhea that is often bloody. The symptoms start happening 4-7 days after the bacteria enters your body and can last anywhere from 1 week to more than 3 weeks.

You normally get it from handling/eating raw/undercooked pork products, especially pork intestines. You can also get it from untreated water and unpasteurized milk.

Viruses

Hepatovirus A

This virus causes hepatitis A. The symptoms include diarrhea, jaundice (yellowish or purplish skin and sclera, dark urine, pale feces), and flu-like symptoms. They start appearing 15-50 days after eating food containing the virus and last anywhere from 2 weeks to 6 months.

You get it mostly from foods that were contaminated by an infected food handler and not properly cooked or reheated. It’s also possible to get it from raw or undercooked shellfish that lived in contaminated water. An effective vaccine for hepatitis A exists and is part of vaccination programs in many countries, including the US.

Norovirus

You might know this virus as the “winter vomiting bug”. It’s one of the most common causes of foodborne illnesses, accounting for about half of all foodborne illness outbreaks in the US. The symptoms include nausea, vomiting (unsurprisingly), abdominal cramps, and diarrhea. Vomiting tends to be more common in children, while diarrhea is more common in adults. In some cases, it can also cause flu-like symptoms. The symptoms start appearing 12-48 hours after getting the virus and last 1-3 days. They may last longer in people with weak immune systems.

Norovirus is extremely contagious. Ingesting fewer than 20 individual viruses can be enough to cause an infection. Since the virus is present in a sick person’s vomit and feces, it’s very easy for that person to contaminate foods and surfaces, especially if he or she doesn’t have strict hygiene. Norovirus can also survive a long time outside the body, adding to its contagiousness. Thorough cooking and bleach-based cleaners can stop the virus.

Other

Cryptosporidium

This is a protozoan parasite that causes nausea, vomiting, slight fever, abdominal cramps, and diarrhea. For most people, the infection stays in the small intestine. But in people with weak immune systems, it can spread to other organs and cause numerous severe, sometimes fatal, complications. The symptoms typically start happening 2-10 days after ingestion, but can take up to a month. They usually last for about 2 weeks, but can sometimes become a recurrent infection (periods of infection with brief recoveries in between) over a span of weeks to months.

You normally get this parasite from anything that’s been in contact with an infected organism’s feces. These can include foods contaminated by an infected food handler or from untreated water. Thorough cooking and hydrogen peroxide can help neutralize Cryptosporidium.

Cyclospora

Another protozoan parasite, Cyclospora is similar to Cryptosporidium in terms of the symptoms it causes and how it spreads. But in addition to the symptoms of Cryptosporidium, it also causes appetite loss and substantial weight loss. Another difference is it seems to only infect humans, so it only spreads from person to person (usually through an infected food handler). It mostly resides in tropical and subtropical areas, so food from these areas is mainly where you get it from.

Giardia

Giardia is another protozoan parasite and is similar to the other protozoan parasites in its method of transmission. But this one causes slight fever, abdominal cramps, loss of appetite and weight, gas and bloating, greasy feces that float, and diarrhea. The symptoms start appearing 1-3 weeks after ingestion and usually last 2-6 weeks.

Toxoplasma gondii

This is a single-celled eukaryote parasite (an apicomplexan, specifically) that causes mild, flu-like symptoms, such as fever, swollen glands, aching muscles, and tiredness. The symptoms start appearing 1-3 weeks after getting the parasite and last 2-4 weeks. Usually only pregnant women and people with weak immune symptoms are at risk. Most people with the parasite don’t have any symptoms at all.

The main source of infection is cat feces. Anything that’s been in contact with cat feces (including soil) can give you the parasite. But it’s also possible to get it from handling raw or undercooked pork, lamb, and venison.

Scombroid Fish Poisoning

This type of food poisoning is the result of eating fish with high levels of histamine in it. It can cause flushed or itchy skin, headache, blurred vision, abdominal cramps, diarrhea, and other symptoms similar to an allergic reaction. The symptoms appear within minutes to an hour after eating the bad fish and can last up to 2 days.

In contrast to most other types of foodborne illness, no particular organism is responsible for scombroid fish poisoning. Instead, it’s a result of the decay process of fish with naturally high levels of histidine. Some examples include tuna, mackerel, sardine, marlin, mahi mahi, amberjack, and herring. If kept at temperatures above 16 °C (60 °F), the histidine in the fish becomes histamine through chemical reactions involving enzymes that bacteria produce. Histamine is heat-resistant, so properly refrigerating (or freezing) fish soon after capture/purchase is the most effective way to prevent it.

Ciguatera Fish Poisoning

Two toxins are responsible for ciguatera fish poisoning: ciguatoxin and maitotoxin. Eating fish containing these toxins causes vomiting, numbness, itchiness, sensitivity to hot and cold temperatures, dizziness, and diarrhea. The time it takes for symptoms to appear depends on the amount of toxin you ate and can vary from 30 minutes to 2 days. The diarrhea can last up to 4 days, while the other symptoms may take a few weeks or even months to go away.

A small, marine organism, Gambierdiscus toxicus, produces the two toxins that cause this kind of food poisoning. It lives in coral reefs in tropical and subtropical waters. Other fish eat it and the toxins pass onto them. Therefore, the toxins get more and more concentrated as you go up the food chain. As a result, you get ciguatera from eating large reef fish, such as sea bass, grouper, and barracuda. You can’t smell or taste the toxins or get rid of them through cooking. So, there’s no way to prevent it except by not eating reef fish.

Dealing with the Symptoms of Foodborne Illnesses

As you can see, most foodborne illnesses cause very unpleasant, but largely non-threatening, digestive problems. Diarrhea and vomiting are usually the most concerning because they can cause dehydration. To alleviate them, make sure to drink plenty of fluids to replace the loss and get lots of rest. Most foodborne illnesses will go away on their own.

If the symptoms are severe (ex. vomiting and diarrhea for more than a few days, fever higher than 38.3 °C (101 °F), bloody/tarry diarrhea, or confusion/lightheadedness), contact your doctor immediately. He or she can prescribe antibiotics and other treatments to help stop the infection from getting worse. Very severe abdominal pain, diarrhea that turns very bloody within 24 hours, and botulism need emergency medical assistance.

Lastly, if you do get a foodborne illness, report it to the proper authorities. It can help identify an outbreak and its source.

General Food Handling Tips to Help Prevent Foodborne Illnesses

When preparing food, follow these tips to help prevent the spread of a foodborne illness:

Wash your hands before and after handling any food, especially raw food. Also wash your hands thoroughly with soap after using the bathroom, changing a diaper, handling a pet, or coughing/sneezing.
Thoroughly wash all foods prior to cooking. Many kinds of bacteria live in soil and on the surfaces of meat products.
Wash all cooking utensils and surfaces, such as knives and cutting boards, after using them. If you’re going to use something for another kind of food, wash it before handling the new food. For example, wash the cutting board and knife you used to cut raw chicken before cutting raw vegetables with them.
Keep raw foods away from cooked foods and from each other to avoid contamination.
Keep hot foods hot (over 60 °C or 140 °F) and cold foods cold (under 4 °C or 40 °F) until consumption. Refrigerate (to under 4 °C or 40 °F) any leftovers within 4 hours of cooking and within 2 hours of them sitting at room temperature. Toss out anything left out longer than that. If the room temperature is over 32 °C (90 °F), you may need to toss anything left out at that temperature after just an hour.
Refrigerate foods using small, shallow containers, if possible. They help the food cool down faster.
Thaw frozen meats using the refrigerator, not by leaving it outside at room temperature.
Use a food thermometer to help you know whether you’ve cooked something thoroughly enough. This guide (from foodsafety.gov) will tell you the correct temperatures for a variety of foods.
Reheat leftovers to over 74 °C (165 °F) before serving. For liquid leftovers, bring them to a boil before serving.

What to Watch out for When You Eat Out

Even if you practice the best food preparation hygiene, it’s largely out of your control if you eat stuff other people made. Here’s what to look out for when eating foods from stores and restaurants:

Pay attention to you senses. If something doesn’t look, smell, or taste right, don’t eat it.
Avoid any sealed containers of food that appear to be bulging. It’s most likely due to gas from bacterial growth.
Read reviews, if possible. If a lot of people seem to be getting sick, you should consider someplace else to eat.
At buffets, look out for foods that appear to have been sitting out at room temperature for too long. One way to tell is to see if the food has leaked its fluids onto the food tray. Freshly cooked foods still retain most of their fluids. In addition, look out for foods that aren’t at the proper temperature. For example, if something is supposed to be hot and the table its on is lukewarm, it’s a sign you should avoid it.
Also for buffets, look out for misbehaving customers. Things to look for are people who use serving utensils from other foods to add food to their plate, use their own utensils or hands to add food to their plate, return food from their plate to the serving table, or cough/sneeze near food. It’s best to avoid food touched by these customers and report them to the buffet staff.
Be wary of eating raw foods like sushi. Raw foods lack a “kill step” in the preparation process. So the food establishment needs to be on point with its food handling procedures to prevent a foodborne illness outbreak. Only eat them from reputable restaurants. People with weak immune systems should avoid them entirely. Similarly, be wary of undercooked foods (ex. rare steak).