The Last Meal I Ate Made Me Sick!

Posted by Eric Troy on 28 Jul 2016 21:21

You just had a great restaurant meal last evening and today, you have food poisoning. That restaurant poisoned me, you think. This is a common assumption. Whenever we get sick with something that feels like food poisoning, we assume the culprit was the last meal we ate. This is, in fact, an incorrect assumption. If it were true, the CDC and local health departments would have a much easier time tracking outbreaks of food-borne illness.

It is certainly possible that your symptoms came from a restaurant you ate at the night before. But, it is also possible for your symptoms to have come from a restaurant you ate at days ago or even a week ago! Symptoms from the most common foodborne pathogens take anywhere from 12 hours to, yes, a week to appear. Usually, they appear within 24 hours after the contaminated food was eaten.

Symptoms from norovirus, the most common type of food poisoning, develop 12 to 48 hours after exposure. So, there is really no way to tell which meal from within this time-frame is responsible unless a family member or friend happens to develop similar symptoms and you both have only one meal in common.

The time it takes for a person to develop symptoms after exposure to a pathogen is called the incubation period. The reason that this period varies is that a few different things can affect it: the number of organisms or dose that reaches the intestine, the virulence of the infecting strain, and the immunity of the person infected.

Let's look at some other time-frames for the more common foodborne illnesses:

Bacterial Food Poisoning Incubation Periods

Source Incubation Period
Bacillus cereus, foodborne 30 minutes to 6 hrs.
Campylobacter 1 to 11 days, usually 3 to 5
Clostridium 6 to 24, usually 8 to 12
E. coli 1 to 10 days, usually 3 to 4
Salmonella 12 to 72 hours
Shigella spp. 1 to 2 days
Staphylococcus aureus 30 minutes to 6 hours, usually 1 to 6
V. parahaemolyticus (Vibriosis) 4 to 30 hours
Yersinia enterocolitica 4 to 7 days

Parasitic Food Poisoning

Source Incubation Period
Cryptosporidium spp. 2 to 10 days, average 7
Giardia intestinalis 1 to 3 weeks
Toxoplasma gondii 4 to 21 days*

* Toxoplasma gondii causes an illness generally known as toxoplasmosis. Many adults may be infected with this parasite and not know it because a healthy person's immune symptom will keep the parasite from causing symptoms. When symptoms do occur, they may be dismissed as a mild case of flu. Since any individual can carry the parasite for long periods of time and become ill due to a weakened state of the immune system, and due to the many factors influencing the onset of symptoms, a precise incubation period is hard to establish. However, toxoplasmosis can be extremely dangerous to people with weakened immune systems or pregnant women, and is the reason pregnant women are advised not to change cat litter boxes, or come into contact with them, as the parasite can be passed in cat's feces. The incubation period given here is only an estimate.

Viral Food Poisoning Incubation Periods

The viruses listed below cause viral gastroenteritis, cause symptoms that are generally indistinguishable. Although the incubation periods can vary, they are poorly defined in the medical literature and difficult to pinpoint with accuracy given the current state of knowledge. Estimates vary from 1 to 2 days up to 3 to 4, or even 5 to 10 (for adenovirus, not listed), For the viruses listed below, I have relied on a systematic analysis of documented estimates carried out by Rachel M Lee, et al. and published in BMC Infectious Diseases 1. These are only estimates.

Source Incubation Period
Astrovirus 1 to 5 days, median 4.5
Norovirus 1 to 2 hours
Rotavirus 1 to 2 days, sometimes 3
1. Lee, Rachel M. "Incubation Periods of Viral Gastroenteritis: A Systematic ReviewIncubation Periods of Viral Gastroenteritis: A Systematic Review." BMC Infectious Diseases 10.1186/1471-2334-13-446 (2013): n. pag. Web. 28 July 2016. <>.

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