Foodborne illness is a serious public health risk. Diagnosing cases of foodborne illness can be important, because in some cases, other people in the community may also be affected if there is an outbreak. An outbreak of foodborne illness occurs when two or more people have the same foodborne disease caused by consuming food from the same contaminated source. Outbreaks of foodborne disease can be reported by individuals who know each other who all got sick after eating the same thing, by doctors who have noticed an increase in cases of a specific illness in the community or by public health departments themselves based on statistics provided by health providers in the community. However, most of the cases of foodborne illness are an isolated incidents and go unreported. Therefore, most of the sources of foodborne illnesses are not identified.
An additional difficulty in controlling foodborne illness is that it is sometimes difficult to confirm the source of the illness. It may be more obvious in some cases where the symptoms occur shortly after ingesting a specific meal, but in some cases of foodborne illness, the symptoms may occur days after the contaminated food is ingested. The patient may not be able to figure out which food they ate that made them sick, or they may attribute their symptoms to the wrong food source based on coincidence in timing.
Clinically, it can be very difficult to distinguish some cases of foodborne illness from a viral infection that causes gastrointestinal symptoms, such as the so-called “stomach flu.” The main symptoms of both conditions are nausea, diarrhea, vomiting, abdominal pain, fever and feeling generally ill. Symptoms such as bloody diarrhea, severe dehydration, severe abdominal pain or unexplained neurological symptoms can implicate severe food poisoning rather than a viral infection.
Samples can be obtained from the patient’s stool and tested for disease-causing organisms if foodborne illness is suspected. If the patient has any of the unusual symptoms described above, it suggests to the doctor to test the patient for bacterial foodborne illnesses. Patients who have recently traveled and are experiencing gastrointestinal symptoms may also be tested for the presence of parasites. Blood tests may also be used, and antibodies can be used to see if a person has been infected with specific organisms. Sometimes, if the source of contamination is known, the food can also be screened for microbiological contamination. In spite of these techniques, foodborne illness is often difficult to diagnose.