Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (142 page)

   Increased colonic motility (e.g., irritable bowel syndrome)

INFECTIOUS GASTROINTESTINAL DISEASES

   Definition

Ingestion of viable pathogenic microorganisms or toxins is responsible for a wide variety of gastrointestinal complaints. Ingestion of toxic nonbiologic agents, such as heavy metals, may also cause gastrointestinal symptoms, as discussed above. Disease is usually manifested by GI tract signs and symptoms but may be manifested by systemic or localized illness without significant GI symptoms (e.g., enteric fever, botulism). Fecal–oral transmission of infectious agents is commonly mediated by contamination of food but may be mediated by contaminated environmental sources. A foodborne illness is any illness related to food ingestion. Foodborne illnesses and other transmissible enteric diseases are of interest to public health authorities, and many are subjected to mandated reporting because of the possibility of widespread dissemination. Department of Public Health epidemiologists often coordinate clinical and laboratory investigations.

A foodborne illness may be restricted to a single individual or a small group, or may represent a large outbreak with many patients linked to a common source of infection. In the United States, enteric viruses cause most infectious diarrhea cases; common bacterial pathogens associated with gastroenteritis are
Salmonella
spp.,
Campylobacter
spp.,
E. coli
(STEC) O157 and
Shigella
spp.

   Who Should Be Suspected?

Patients with foodborne illness usually present with a variety of symptoms including nausea, vomiting, abdominal pain, diarrhea, and anorexia. Certain foodborne illnesses, however, may be associated with minimal GI symptoms but have prominent systemic or localized symptoms.

Diarrheal illness may be noninflammatory or inflammatory. Noninflammatory diarrhea is usually caused by disease of the small intestine resulting in hypersecretion or decreased absorption. There is usually abrupt onset and resolution after a brief duration of illness. Systemic symptoms are usually absent or mild. Dehydration may be a complication, especially in the young or elderly.

Inflammatory diarrhea is characterized by mucosal invasion or cytotoxic damage by the pathogen. The large intestine is most commonly affected. The mucosal invasion typically results in bloody stools with many fecal leukocytes. Systemic symptoms are typical, including fever, abdominal pain and tenderness, nausea and vomiting, headache, and malaise.

When evaluating a patient with a likely foodborne illness, a number of issues should be pursued:

   What is the interval between likely exposure and onset of symptoms?

   What is the duration of clinical symptoms in affected patients?

   What are the prominent signs and symptoms of disease?

   Does any of the patient’s recent contacts have similar illness?

   Has the patient eaten any unusual food? Eaten at any function with massproduced meals? Eaten any raw or incompletely cooked or pasteurized food?

   Has there been new contact with animals: domesticated, farm, or wild?

   Has the patient had recent travel to regions where foodborne illness is endemic?

   Does the patient, or does a close contact, attend or reside in a day care center, long-term care facility, or other facility at which transmission of an agent may be facilitated?