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Foodborne disease is an illness that occurs in 2 or more people after the consumption of common food source. Contamination can come from bacteria, viruses, or protozoans. Viruses are the most common source, including Norwalk-type (58% overall, United States), astrovirus, rotaviruses, and enteric adenoviruses. Bacterial sources include nontyphoidal Salmonella (11% overall, most common cause for hospitalization and associated death in the United States), Clostridium perfringens, Campylobacter spp, Listeriamonocytogenes, Shigella spp, Shiga toxin producing Escherichia coli (STEC) and Staphylococcus aureus. Parasitic causes include Giardia lamblia, Toxoplasma gondii, Entamoeba histolytica, and Cryptosporidium. The most common associated foods are poultry, leafy vegetables, and fruits/nuts. In addition, after eating reef fish that feed on certain dinoflagellates (algae), patients may experience scombroid or ciguatera poisoning which is a toxin induced syndrome.
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Waterborne diseases occur from ingestion of, or contact with contaminated water, from swimming pools, hot tubs, spas, or naturally occurring fresh or salt water. Symptoms are can be either GI or dermatologic. Common organisms include the majority of those associated with foodborne illness plus Vibrio species, Aeromonas species, Pseudomonas aeruginosa, Yersinia species, Hepatitis A, nontuberculous Mycobacterium and less frequent organisms.
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Symptoms of both foodborne and waterborne illness include vomiting, diarrhea, abdominal cramping, fever, dehydration, malaise, and in some, bloody stool. Physical exam may be remarkable for features of dehydration, and in some, stool positive for frank or occult blood. Prolonged illness beyond 2 weeks suggests protozoan parasites. STEC may be complicated by hemolytic uremic syndrome (decreased urine output, symptoms of anemia), especially after antibiotic treatment. STEC classically presents with vomiting, moderate to marked stomach cramps, diarrhea (often bloody) and mild fever, not over 101°F/38.5°C.
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Patients with scombroid fish poisoning or ciguatera poisoning have symptoms similar to foodborne illness described immediately above, 1 to 24 hours after ingestion of reef fish. In addition, patients with scombroid poisoning frequently have flushing and headache due to histamine reaction. Those with ciguatera poisoning may have headaches, muscle aches, paresthesias, or a burning sensation on contact with cold, due to sodium channel mediated nerve depolarizations. Neurologic symptoms may be prolonged beyond the ED visit.
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The skin manifestations of waterborne illness vary from simple cellulitis, the painful indurated plaque of Mycobacterium marinum, to necrotizing infections which may include hemorrhagic bulla with Vibrio vulnificus. Patients with Aeromonas hydrophila skin infections often have a history of trauma associated with freshwater exposure, and may have foul smelling wounds.
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Bedside testing for fecal occult blood is the most commonly indicated test; otherwise most patients need no laboratory testing, unless significantly dehydrated or other significant diagnoses are being considered. For those more acutely ill, consider fecal leukocytes, the neurophil marker lactoferrin, electrolytes, and complete blood count. Stool gram stain may reveal Campylobacter. Stool cultures are more likely to be positive in those with positive fecal leukocytes or lactoferrin. STEC and Vibrio cultures require specific procedures ...