Thursday, March 3, 2011
WAS IT SALMONELLA IN THE EGGS? A FOOD POISONING CASE STUDY
Last night a good friend told me had recently had a miserable case of food poisoning. Since he reads this blog, as do several other mutual friends, let's just call him Joe. Joe is over 65 years old, owns and runs his own company, physically active, and relatively healthy. Here's the sad tale he told me.
Joe had gone to his usual pastry shop for coffee and a custom-made pizza after a bike ride in San Francisco. He asked for the following on the pizza: egg whites, smoked salmon and fried onions. Three hours later, just as he was starting a very critical meeting with an important new client, he started to have stomach cramps. All he wanted now was for the meeting to finish. As soon as the client walked out the door he began vomiting and continued to vomit violently all night. He recovered in about a day. Joe was convinced that there had been salmonella in the eggs on his pizza. But was it the eggs, and was it Salmonella bacteria?
Let's look at four possible causes in Joe's case - all of which are commonly associated with restaurant food, starting with Salmonella. Since he did not go to a doctor, we'll never know what it was, but have a guess. By the way, his case will not be reported as a food poisoning statistic either - as most aren't.
Salmonella bacteria can get into almost any food and at any point between the field and plate, although they are most likely to be in foods of animal origin. Food workers may also carry Salmonella and pass them on. Most persons infected with Salmonella develop diarrhea, abdominal cramps and fever. Onset of symptoms usually occurs 12-72 hours after eating. Luckier victims recover in as little as 48 hrs, but usually it's 4-7 miserable days. It can be even longer if complications set in (that is, if it gets into bloodstream, requiring hospitalization).
Listeria monocytogenes is also becoming a major public health problem. Unlike Salmonella, the onset of symptoms can be very slow - 3 to 20 days, and occasionally even longer. Victims tend to have fever and muscle aches (like flu) and sometimes a stiff neck. Gastrointestinal symptoms aren't always present. Like Salmonella, L.monocytogenes is found in soil and water, but can get into food at any point. It is often present in ready-to-eat foods, most likely because a high percentage of food workers carry it - some estimates are as high as 30 percent.
Staphylococcus aureus is another bacterium that commonly causes food poisoning, especially in restaurants. It could get into food from the nose or skin of a food workers (it is believed that up to 25% may carry it without symptoms). Onset of symptoms is caused by the Staph toxins and occurs very quickly - in perhaps as little as 30 minutes, but usually, 1-6 hrs and normally includes several of the following: nausea, retching, vomiting, stomach cramps, and diarrhea, lasting about one day, but sometimes up to 3 days.
Norovirus is the most common cause of food poisoning and is a very contagious virus. It usually gets into food directly from food handlers, and sometimes from contaminated surfaces or kitchen tools. Onset of symptoms is usually 24-48 hours after eating contaminated food, but occasionally it is earlier, and includes very bad vomiting, watery non-bloody diarrhea with abdominal cramps, and nausea. Luckily, recovery is almost always within 1-3 days (and, miserable nights).
A final thought - we tend to think that we got food poisoning from the last meal we ate. This could be true, but it may not be. As you see from the preceding, the onset of symptoms could range from 30 minutes to 20 days - just with these four possible causes. And there are others. Could Joe have got the food poisoning from something else he ate?