Is it the last meal I ate that made me sick?
Posted: February 27th, 2009 - 10:36am by Casey Jacob
Michael Bauer writes the Between Meals column for the San Francisco Chronicle. Yesterday Bauer responded to an e-mail from a reader who had met a friend for lunch one day and explained,
“We both became quite ill an hour or so after we finished our meal.”
The diner wanted to know what to do if the restaurant food made them sick. Bauer responded by saying,
“Most common forms of food poisoning take anywhere from four to eight hours to incubate.”
It is not likely that the two diners were sickened by food eaten an hour before they felt ill.
A handy table from the FDA’s Bad Bug Book shows that the only bacterial foodborne illness known to show symptoms in fewer than two hours is Staphylococcus aureus. (That’s because this particular bacterium produces toxins before it’s even eaten; others don’t produce toxins until they’ve been sitting in your gut for a while.)
Even then, the average time between eating Staph-contaminated food and feeling sick is 2-4 hours. Very few feel sick in just an hour.
A physician commenting on Bauer’s response suggested that the two friends could have been exposed to a gastrointestinal virus earlier in the week that finally showed symptoms after eating at the restaurant together.
Rotavirus takes about two days to make you sick and symptoms of a norovirus can appear in a day or two.
After getting a few more details from the reader, Bauer said,
“I figured that it might have been spoiled fish, since what was consumed was fried and any off flavors might have been masked. However, tracing it back for sure is extremely difficult.”
Depending on the pathogen, a person with a foodborne illness will either start vomiting within a few hours or have diarrhea within a few days. In either case, the last thing you ate is often not the culprit.
A friend of mine, who is now a dietitian, has been keeping a food journal since high school. If she’s ever hit with a foodborne illness—and goes to the doctor, has a stool sample tested, discovers which bug made her sick, and remembers when she started feeling bad—she’ll have an excellent shot at figuring out which food made her sick and where she ate it.
If a sick person can only remember the last place they’ve eaten, though, they’re not considering all the possibilities—including the most likely possibilities.