154. Foodborne and Waterborne Diseases


Typical foodborne causes: Norwalk-type, astroviruses, rotaviruses, enteric adenoviruses. Usual foods: poultry, leafy vegetables, fruits/nuts.

Staph aureus (usually meats/potato or egg salad, left out pastries), Bacillus cereus, Clostridium botulinum create preformed toxin so symptoms usually rapid with vomiting within 1-6 hrs.

Vibrio (usually water based or shellfish), Shigella, Shiga-toxin producing E.Coli produce toxin after ingestion and usually cause diarrhea (sometimes bloody) with abdominal cramping at 24 hrs. Clostridium prefringens most common toxin induced – usually just diarrhea, vomiting rare.

Foodborne Diseases

Typically nausea/vomiting, diarrhea, abdominal cramping. Occasionally fever, dehydration, malaise.

CDC Top 5 pathogens: Norovirus, Salmonella, nontyphoidal, Clostridium perfringens, Campylobacter, Staph Aureus.

Typical gastroenteritis with primarily vomiting: viruses, norovirus, rotavirus, astrovirus, staph aureus, bacillus cereus (fried rice).

Watery nonbloody diarrhea: ETEC (enterotoxigenic E.Coli), Giardia, Vibrio cholerae, Enteric viruses, Cryptosporidium, Cyclospora.

Grossly bloody diarrhea with fever: Shigella (high virulence, seizures in kids), Campylobacter (poultry, MC bacteria), Salmonella (2 MC bacteria, eggs/poultry, dairy, fruit/vegs), ETEC, EHEC (Shiga toxin producing EColi O157:H7, usually grossly bloody diarrhea), Vibrio parahaemolyticus, Yersinia (pork, tofu, shellfish, looks like appendicitis), Entamoeba.

Persistent diarrhea: Parasites such as Giardia (tx w flagyl), Cyclospora (tx w bactrim), Entamoeba (tx w flagyl), Cryptosporidium (supportive).

Neurologic symptoms with disease: Botulism, Scombroid, Ciguatera, tetrodotoxin (puffer fish, toxin still present w cooking – ascending paralysis, dilated pupils, death in 4-6 hrs, usually only lasts a day), toxic mushroom, paralytic shellfish (shellfish, usually w red tide months (months wo r) clams, mussels – numbness, dizziness, myalgias, confusion, memory loss, coma), GBS.

Systemic illnesses: Listeria (cheese, dairy, deli meats, hot dogs), Brucella (raw milk/cheese), Salmonella typhi, S. paratyphi, V. vulnificus, Hepatitis A/E.

Scromboid: due to ingestion of Scombridae fish (tuna, mackerel, bonito, others: maui-mahi, bluefish, herring, sardines). Metallic, peppery taste when eating the fish. Toxin saurine causes by histamine produced. Occurs 30m to 24 hrs after ingestion. Flushing, headache, abd cramping, vomiting, diarrhea. Last 8 hrs. Tx with antihistamines.

Ciguatera: eating reef fish that ingests plankton (dinoflagellate Gamberdiscus toxicus – produces ciguatoxin). Usually with grouper, snapper, amberjack, barracuda (MC). Starts with GI symptoms (N/V/diarrhea) early on, then hypesthesias, paraesthesias, numbness, malaise, generalized weakness, hot/cold reversal, looseness in teeth. Can get hypotension/bradycardia. Neuro symptoms can last months to a year. Supportive tx. Gabapentin/amitripyline controversial. Mannitol found not to be beneficial

Complications: reactive arthritis after Salmonella, Shigella, Campylobacter. Guillain-Barre syndrome can occur 7-21d after Campylobacter. HUS occurs with kids (acute renal failure, hemolytic anemia, thrombocytopenia) with shiga toxin (ETEC, STEC, Campylobacter, Citrobacter, Shigella, Salmonella, Yersinia) and TTP in adults.

Waterborne Diseases

Due to ingestion of contact with contaminated water such as swimming pools, hot tubs, spas, naturally occurring water. Pathogens usually due to fecal contamination, though some are indigenous (Pseudomonas aeruginosa, Vibrio, Aeromonas, nontuberculous mycobacterium, Legionella).

Campylobacter – water contaminated with wild bird feces. Ecoli H157 due to farm animal faces contamination.

Vibrio cholera – due to fecal water contamination. Vibrio vulnificus causes life/limb threatening necrotic wound infections (hemorrhagic bullae). Usually in Gulf coast and due to open wounds exposed to seawater. High rate of sepsis and amputation. Mortality 17-24%. Tx with doxycycline + ceftazidime.

Aeromonas – fresh and marine waters, associated with wound infections. Usually cellulitis, though can get necrosis. Rarely diarrhea. Tx w/ cipro BID.

Pseudomonas aeruginosa – in normal hosts, can cause otitis extern and skin infections such as hot-tub folliculitis. Does not usually cause diarrhea in normal hosts. Tx w/ cipro.

Nontuberculous mycobacterium – found in salt/fresh water. Mycobacterium marinum can cause granulomatous skin infection (painful indurated plaque).

Legionella – usually fresh water; infection caused by inhalation of aerosols. Pontiac fever – flu-like illness, lasts 2-5 d, no tx needed. Also legionnaires disease.

Giardia – most common intestinal parasite. Usually surface water with mountain stream, related to beavers. Usually affects backpackers, campers, travelers. Most asymptomatic, but usually causes acute/chronic gastroenteritis.

Cryptosporidium – very common; usually contaminated recreational water. Look for oocytes in stool. Usually self-limited diarrhea, but in immunosuppressed can cause chronic/life-threatening course.

Entamoeba histolytica – intestinal amebiasis. Usually migrants and travelers in the US. Can cause mild diarrhea to dysentery. Can seed to the liver and cause abscess.


Consider stool cultures if patient febrile, bloody diarrhea, severe or protracted diarrhea. Really only need to check for ova/parasites in immunocompromised or prolonged course. Fecal leukocytes (lactoferrin similar, more sensitive though not readily available, present in breast-fed infants) predicts invasive pathogen – stool culture will better sort out bug, though cannot differentiate inflammation from IBD. Stool hemoccult – as good as fecal leukocytes in predicting inflammatory diarrhea and response to therapy. Stool gram stain looks for Campylobacter. Parasites tx with Flagyl 750mg TID x 7-10d. Always think about testing for Cdiff when you are sending stool for other things.


Hydration and supportive care. Without fever and bloody diarrhea, consider anti motility agents (loperamide) for mild-moderate diarrhea. Avoid antimotility with dysentery (fever/bloody diarrhea). No anti motility agents for children. Consider lactobacilli to shorten diarrhea course (NNT). Most bacteria self-resolve.

Consider abx with: fever > 38.5C, severe abd pain, bloody diarrhea, duration > 48 hrs, positive fecal leukocytes/lactoferrin or usually travelers diarrhea. Tx with PO Cipro 500mg BID x 3-5d (can also give 1g Cipro x 1), PO Levafloxacin 500mg qd x 3-5 days, PO Bactrim double strength BID x 3-5d.¬†Consider doxycycline with vibrio cases. Azithromycin 500mg qd x 3-5d for pregnant women,children, pts in areas with fluoroquinolone-resistant campylobacter (Thailand). Always think about EHEC (don’t give abx). Send specific stool study for it and wait/see.

Do not give abx for suspected EColi H7:O157 due to increased risk of HUS (15%) – usually bloody diarrhea, usually don’t have fever – seems impossible to differentiate from inflammatory diarrhea – recommend sending stool cx and wait/see. Abx effect is usually modest at best.

Giardia/Entamoeba: Flagyl; paromomycin for pregnancy. For cryptosporidium, usually self-limited. For HIV, get CD4 > 100 for resolution.

Clinical Cases

Life in the Fast Lane, Toxicology Conundrum, Seafood Poisoning

The Poison Review, Ciguatera outbreak in New York City


Tintinalli, Seventh Edition, Chapter 154: Foodborne and Waterborne Diseases

Crashing Patient, Scott Weingart, Diarrhea and Food Poisoning

EMRAP, C3 Project, Amal Mattu / Rob Rogers, Diarrhea

EMRAP, August 2012, Chris Cresswell, RANT!: ABX for Diarrhea

AAEM 18th Scientific Assembly, Joseph Bushra, I Have Food Poisoning from That Chinese Place

154. Foodborne and Waterborne Diseases

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