Wilderness and Rescue Medicine 8th Edition

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Section V: Environmental Medicine

is also very short-lived, usually resolving within 24 hours (an exception is Ciguatera, discussed below). You should suspect an active infection in any GI illness that lasts longer than a day. A bacterial infection of the gut should be considered serious and should be treated aggressively with antibiotics or evacuation. It may be impossible to distinguish a mild gas- troenteritis caused by a viral infection from food poisoning because the signs and symptoms are often the same. Your primary clue will be the mechanism of injury (MOI). You should suspect food poisoning when several people who ate the same meal develop the same symptoms at the same time. Identification and elimination of the contaminated food and thorough cleaning of dishware should be part of the plan.

reliably detected and is not destroyed by cooking. Ciguatoxin produces GI and systemic neurologic symptoms, such as numbness, tingling, cramping, and reversal of hot and cold sensation that may persist for weeks. Ciguatera toxin can be avoided by restricting the diet to fish smaller than about one kilogram.

Ingested Toxins

General Principles

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Ciguatera: • Neurotoxin from reef dwelling dinoflagellates concentrated in larger predatory fish • Not destroyed by cooking or freezing • Symptoms include vomiting, diarrhea, abdominal cramping, paresthesia, dysuria, metallic taste, temperature-related sensory defects. • Generic treatment is symptomatic, including volume replacement. • There are no proven specific treatments.

Ingested Toxins

General Principles

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Scombroid toxin is a histamine-like substance produced by bacteria growing on the surface of dead fish in storage. Scombroid produces a histamine-like response including hives, itching, and flushed skin. It can be difficult to distinguish from an allergic reaction. Fortunately, the treat- ment is the same.

Food Poisoning: • Preformed toxins like Staph enterotoxin, or ingested pathogens like Norovirus, Clostridium , or E. coli . • Most cause nausea, vomiting, watery diarrhea, usually resolving within 72 hours. • Most serious cause volume shock and/or inflammatory diarrhea with blood or pus, fever (e.g. Salmonella , Campylobacte r). • Treatment is generally supportive, with antibiotics for persistent or inflammatory diarrhea.

Ingested Toxins

General Principles

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Scombroid: • Histidine in fish flesh converted by histamine by bacteria in fish stored in temps >4°C. • Not destroyed by cooking or subsequent freezing or refrigeration. • Symptoms generally develop with an hour. Flushing of the face, urticarial rash, diarrhea, headache are common. • Sx rapidly improve with administration of antihistamine.

Viral gastroenteritis can affect a group in a simi- lar way, but usually people will develop symptoms sequentially; early cases are improving while new cases are just developing. Thorough cleaning of dishware and hands is part of the plan, along with preventing symptomatic people from participat- ing in food preparation or cleanup. Fortunately, in mild cases the field treatment of food poisoning and viral gastroenteritis is the same: hydration, easily digested foods, and time. Ciguatera, scombroid, and paralytic shellfish poisoning are foodborne toxins worthy of special mention for the marine environment. Ciguatoxin is produced by a reef-dwelling dinoflagellate that is consumed by coral and other reef animals. It is concentrated up the food chain, reaching danger- ous levels in larger predatory fish. It cannot be

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Paralytic shellfish poisoning occurs with con- sumption of clams or oysters that have concen- trated an algae-produced neurotoxin. It is not destroyed by cooking. Symptoms include nau- sea, vomiting, diarrhea, abdominal pain, and tingling and burning sensations of the mucous membranes and skin. Respiratory paralysis can develop in severe cases. Treatment is primarily