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The warmer days of summer are fraught with peril. It comes in the form of the food we eat, and is more likely to occur when someone else prepares your food. More directly, it is related to poor food storage, improper handling and under-cooking when ambient temperatures accelerate bacterial growth. The symptoms range from nothing more than a mild stomach upset all the way to experiencing blood heavy diarrhea, fever, vomiting, dehydration and hospitalization. My adolescent son, Andrew, is a good case in point. Iron bowels that accept 3-day-old pizza, milk-less cusps of sugar also known as cereal, assorted meats barbecued to a blushing shade of pink and yet the thought of sliced tomatoes throw this honed system into a tizzy. The truth of the matter is that our immune system does protect us from an awful lot of the assorted microbes that hitch a ride on our food. It comes as no surprise when we notice that immunodeficient persons suffer more food poisoning. These include infants, the elderly, diabetics, cancer patients and people taking medicines that modify immunity.
About 75% of food poisoning is due to bacterial culprits, but we also see parasites such as giardia and toxoplasmosis, viruses such as Hepatitis A and rotavirus, and chemicals in the form of pesticides, mushroom toxins, fungal aflotoxins and reef fish poisons. These last few are the easiest to diagnose because numerous symptoms appear almost immediately and you know that you are in trouble.
There are some clues to deciphering what food caused your illness. When nausea and vomiting begin within 6 hours of ingestion, it suggests that you ate something containing a toxin. Bacteria such as Staphylococcus aureus and Bacillus cereus produce toxins that reside on foods. These toxins can produce symptoms within hours of ingestion. Bacillus is found most commonly in cooked rice and vegetables that sit at room temperature for long periods of time. S.Aureus is a culprit found in deli-meats, fish, canned mushrooms, cheese, dairy products and poultry. Cramps and diarrhea that begin 7 to 17 hours after ingestion are often associated with another type of toxin produced by Clostridium perfringes bacteria. This is more commonly seen after consumption of contaminated meat pies, stews, gravies and seafood.
Fever may appear once bacteria successfully invade through the bowel walls into the blood. This takes between 12 to 48 hours. This is associated with the classic Salmonella poisoning which is the most common type. Salmonella has many sub-types including typhoid and is found in common meats, eggs, dairy and poultry, but also in uncommon sources such as peanuts, vegetables and chocolate. The typhoid sub-type is rare but dangerous. Other bacteria also produce these symptoms. Shigella is found in egg salads and mayonnaise. Campylobacter is found in clams, shellfish, pork, poultry and milk. And of course, the rare "hamburger disease" is caused by toxic strains of E.Coli.0157:H7 found in cattle feces that put Walkerton on the map. This contrasts with the friendly E.Coli. happily living in our gut. After a day or so, some of these bacterial invasive species produce cytotoxins that interfere with bowel functions and watery diarrhea results. When affected by bacteria produced toxins such as the verotoxin of "hamburger disease," inflammation and bleeding ensue. This results in bloody diarrhea and possible kidney failure.
Contamination of food is often caused by persons handling the food. Poor hygiene and improper preparation are common sources of contamination. Frequent hand washing and frequent utensil washing help. Contamination can be limited to a small portion of food. For example, it may only affect the first steak off the grill that is placed on the same plate used to season the raw meat. In this case, it follows that only the person eating that steak and no one else stands to get ill. Use your sense of smell. If it smells bad, avoid it. Cooked food which has sat out for more than 2 hours should be viewed with suspicion. When re-heating, ensure the food is steaming hot. Use a temperature probe for cooking. Wash fruits and vegetables well using a scrub brush. In unfamiliar territory, try to sneak a peek at the prep area if possible. If you would not be tempted to cook there, then do not eat there. Remember the next time you have a loose bowel movement that it may be more than just wholesome food selection. Statistically, we will all suffer 2-3 bouts of some form of food related symptoms each year. I thank my esteemed scope-ready colleague, Dr. Roger Hollingsworth, for some gut-wrenching discussion and for reminding me that "beer does not kill everything."
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