Wilderness and Rescue Medicine 7th Edition Jeffrey Isaac, PA-C and David E. Johnson, MD

Wilderness and Rescue Medicine 188

concentrations. Lemon/eucalyptus is listed by the United States CDC as an alternative, but is much less effective against mosquitoes, not proven against malaria vectors, and not effective against ticks.

Chapter 23 Review: Toxins, Envenomation, and Disease Vectors

• Toxic substances can produce systemic effects, local effects, or both. • A toxin can also be an allergen, causing a release of histamine in addition to its toxic effects. • Toxins that produce significant systemic effects are serious and require emergency evacuation. • High-risk ingestions like drug overdoses warrant immediate evacuation to medical care and, if available, an antidote. • Toxic inhalation can injure the respiratory system. The anticipated problems include respiratory distress. • Toxins injected by snakebite or other envenomation come in two basic forms: tissue toxins and neurotoxins. Pit viper envenomation is mostly tissue toxin. • The anticipated problems with pit viper envenomation include swelling, pain, shock, organ failure, and infection. Aggressive hydration and urgent evacuation to antivenin is the ideal treatment. • Coral snake envenomation is neurotoxic. Anticipated problems include numbness, cramping, and respiratory paralysis. Evacuation to a hospital is the ideal treatment. Antivenin may not be available. • Nematocyst envenomation (jellyfish, man-of-war) is primarily neurotoxic. The treatment is removal of the nematocyst-bearing tentacle with sea water or vinegar and symptomatic treatment of pain and inflammation. Fatalities are limited to massive man-of-war stings or indopacific box jellyfish. • Marine spiny envenomation is treated with hot water immersion to inactivate the toxin. The antici- pated problem is infection from a high-risk puncture wound. • Arthropod envenomation is generally more painful than serious (except for anaphylaxis). Treatment is symptomatic with pain medication and topical or systemic antihistamines. • Prolonged, systemic, or progressive symptoms deserve medical evaluation. • Toxic loading is the cumulative effect of many bites or stings, such as several hundred black fly bites. Treatment is symptomatic with NSAIDs and antihistamines. • Tick paralysis is caused by a neurotoxin. Removal of the tick cures it. • Many serious diseases are transmitted by arthropod vectors like mosquitoes and ticks. Diagnosis and treatment may be difficult. Avoidance and using protective clothing, nets, and repellent is the ideal field treatment.