Foodborne disease may occur after consumption of food contaminated with bacteria, viruses, parasites, chemicals, or biotoxins. Viruses such as norovirus, astrovirus, rotavirus, and enteric adenovirus are the most common sources, with norovirus causing over half of all cases. Bacterial disease is often more severe and includes nontyphoidal Salmonella, which is the most common cause for hospitalization and associated death in the United States. Other bacterial causes may include Clostridium perfringens, Campylobacter spp., Listeria monocytogenes, Shigella spp., Shiga toxin-producing Escherichia coli, and Staphylococcus aureus. Parasitic causes include Giardia lamblia, Toxoplasma gondii, Entamoeba histolytica, and Cryptosporidium. In addition, patients may experience symptoms of scombroid or ciguatera poisoning after eating some types of fish associated with these toxin-induced syndromes.
Waterborne diseases occur from ingestion or contact with contaminated water. Symptoms are most commonly gastrointestinal or dermatologic in nature. Common organisms include those associated with foodborne illness as well as Vibrio species, Aeromonas species, Pseudomonas aeruginosa, Yersinia species, hepatitis A, nontuberculous Mycobacterium, and other less common organisms. The most common pathogen responsible for recreational waterborne disease outbreaks is Cryptosporidium.
Symptoms of both foodborne and ingested waterborne illness include nausea, vomiting, diarrhea, abdominal cramping, fever, dehydration, and malaise. A history of multiple family members or closely associated individuals with simultaneous symptoms is supportive of a suspected foodborne or ingested waterborne illness. Physical exam may reveal findings of dehydration, and some patients will have stool positive for frank or occult blood. Prolonged illness beyond two weeks suggests protozoan parasites. Shiga-toxin producing Escherichia coli (E. coli) infections may present with vomiting, abdominal cramping, bloody diarrhea, and mild fever, and may be complicated by hemolytic uremic syndrome, especially if antibiotic treatment is prescribed.
Patients with scombroid fish or ciguatera poisoning have symptoms similar to other foodborne illnesses and typically present one to six hours after ingestion. In addition to nausea and vomiting, patients with scombroid poisoning frequently have flushing and headache due to a histamine-mediated reaction. Those with ciguatera poisoning may have headaches, muscle aches, paresthesias, reversal of hot and cold sensation, or sensitivity to extreme temperatures, due to sodium channel-mediated nerve depolarizations.
The skin manifestations of waterborne illness may include localized cellulitis, painful indurated plaques of Mycobacterium marinum, or necrotizing infections and hemorrhagic bulla associated 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.
DIAGNOSIS AND DIFFERENTIAL
Diagnostic testing is often not indicated as most of these illnesses are self-limited. For those patients who are more acutely ill, or if other significant diagnoses are being entertained, consider stool cultures with Gram stain, the neutrophil marker lactoferrin, electrolytes, and complete blood count. Fecal leukocyte testing is neither sensitive nor specific for invasive disease, and is a poor predictor of ...