Foodborne Illnesses: 5 Things Primary Care Physicians Need to Know Now

March 20, 2012

Obtain an accurate food/water ingestion history; be suspicious of bacteria, protozoa, and environmental toxins; educate patients on good kitchen hygiene. Here, a few more essentials to keep in mind when you suspect a foodborne illness.

1. In assessing the possibility of food-borne illness, it is important to obtain an accurate food/water ingestion history, the kinds of symptoms that develop (fever, nausea/vomiting, diarrhea, non-gastrointestinal), and the time between ingestion of a suspected vehicle and onset of symptoms.

2. There are many causes of food-borne illness, including viruses (such as Norovirus), bacteria (such as Salmonella and Campylobacter), protozoa (such as Giardia), worms (such as tapeworms), bacterial/algal toxins (Staphylococcus, Clostridium botulinum), and environmental chemical toxins.

3. Adequate cooking of food kills pathogenic organisms and helps minimize the risk of food-borne illness. It is also important to practice good kitchen hygiene, which includes not placing the cooked food into an uncleaned vessel where the uncooked food had just been.

4. Two of the most common causes of food-borne illness associated with vomiting are staphylococcal enterotoxin and Norovirus. The incubation period of staphylococcal toxin disease is quite short (usually 4 to 6 hours); the disease does not spread from person to person, it is not usually associated with substantial fever, and it usually does not cause diarrhea. Norovirus (or Norwalk-like virus) infection tends to have a longer incubation period, easily spreads, and often causes fever and diarrhea as well.

5. It is important to realize that the last thing the patient has eaten is not necessarily the cause of the illness. As an example, if an individual eats a hamburger and develops fever and diarrhea within 6 hours with the growth of Salmonella from the stool, the vehicle of the salmonellosis was not the hamburger, even if it was undercooked, since the incubation period of salmonellosis is longer than 6 hours.

Bonus Point
Not all food-borne illnesses can be prevented by adequate cooking of the food. Most of the heat-stable causes are toxins, including staphylococcal enterotoxin illness and Bacillus cereus enterotoxin. The 2 more notable fish-associated food-borne illnesses are ciguatera (which causes a variety of neurological symptoms) and scrombroid (which causes an allergic-like illness).

References for further reading:

Lund BM, O’Brien SJ. The occurrence and prevention of foodborne disease in vulnerable people. Foodborne Pathog Dis. 2001;8:961-973.

Nyachuba DG. Foodborne illness: is it on the rise? Nutr Rev. 2010;68:257-269.