Does Your Patient Have a Foodborne Disease?

David W.K. Acheson, MD, FRCP


April 01, 2002

In This Article

Nongastrointestinal Manifestations

As mentioned, some foodborne pathogens can cause serious nongastrointestinal illness. Neurologic symptoms are a common feature of many such foodborne agents. While it is beyond the scope of this section to discuss each disorder in detail, several are clinically important and deserve discussion (Table 4).

Botulism (due to C botulinum toxin) is one of the most important foodborne diseases because of its life-threatening consequences. In patients demonstrating visual disturbance or descending paralysis, a food history may be critical. Botulism is associated with the consumption of foods in which C botulinum spores have germinated, and the resulting vegetative cells have produced toxin. Typical foods associated with botulism are those canned at home, fermented fish, herb-infused oils, and foods held warm for extended periods of time. Food, serum, and stool can be tested for toxin by reference laboratories.

Ciguatara toxin may initially (2-6 hours) cause nausea, vomiting, diarrhea, and abdominal pain. These signs and symptoms are followed by paresthesia, weakness, or reversal of hot and cold sensations, among other neurologic symptoms that can progress to cardiovascular abnormalities in 2-5 days. Ciguatara toxin is associated with consumption of large reef fish, such as grouper, red snapper, amberjack, and barracuda, which become contaminated by their consumption of algal blooms containing dinoflagellates. It is the dinoflagellates that produce the heat-stable ciguatoxin that becomes concentrated as it moves up the food chain.

Scromboid occurs within minutes to hours of consumption of certain fish (such as blue fish, tuna, mackerel, marlin, or mahi mahi) or occasionally cheese, in which biogenic amines, especially histamine, have built up. Signs and symptoms include flushing, a burning sensation, urticaria, dizziness, and paresthesia.

Shellfish may also contain toxins, which fall into 3 groups: diarrheic, neurotoxic, and amnesic. These toxins cause various symptoms, as their names imply. Symptoms usually occur within 30 minutes to several hours following exposure. There are a variety of mushroom toxins that result in a mixture of gastrointestinal and neurologic disturbances, including hallucinations and confusion. Tetrodotoxin from puffer fish has a rapid onset (< 30 minutes) of neurologic, respiratory, and cardiac complications that are usually fatal. A food history is essential if tetrodotoxin is in the differential diagnosis.

Listeria monocytogenes

L monocytogenes causes listeriosis, which is a rare but deadly foodborne disease with a mortality rate close to 20%. It is most likely to occur in immunocompromised or elderly persons or in pregnant women. Exposure to deli meat, raw hot dogs, and unpasteurized soft cheese is a risk factor that needs to be taken into consideration, but the incubation period may be as long as 6 weeks. The diagnosis is usually made by culturing L monocytogenes from blood or cerebrospinal fluid. Five percent to 10% of the population has L monocytogenes in their stool, so stool culture is unhelpful. L monocytogenes has occasionally been known to cause gastrointestinal symptoms and fever with a short (10- to 48-hour) incubation period in healthy adults.

Vibrio vulnificus

V vulnificus is another unusual but deadly microbe that affects immunocompromised individuals, especially those with chronic liver disease. It is associated with exposure to raw shellfish and has an incubation period of 1-7 days. This type of infection may present with gastrointestinal symptoms or skin infection that rapidly develops into bacteremia and systemic disease. Culture for vibrios requires special media and is not done routinely; a special request should therefore be made to the laboratory if V vulnificus is suspected.

Toxoplasma gondii

T gondii infection usually occurs after accidental contamination of food with the parasite oocysts from cat litter boxes or the garden, or from undercooked hamburger (steak tartar). It is often asymptomatic in normal hosts, but may be deadly in immunocompromised persons with pneumonitis, myocarditis, and neurologic symptoms. Vertical transmission occasionally occurs during pregnancy, leading to congenital toxoplasmosis.

Hepatitis A is transmitted from raw shellfish and various other foods after contamination by an infected food-handler. The incubation period varies from 15-50 days; determining a source can therefore be very difficult. The diagnosis is confirmed by serologic testing.