Show Summary Details
Page of

Injuries, envenoming, poisoning, and allergic reactions caused by animals 

Injuries, envenoming, poisoning, and allergic reactions caused by animals

Injuries, envenoming, poisoning, and allergic reactions caused by animals

David A. Warrell

Page of

PRINTED FROM OXFORD MEDICINE ONLINE ( © Oxford University Press, 2015. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Medicine Online for personal use (for details see Privacy Policy).

date: 30 March 2017

Mechanical injuries

Attacks by wild and domesticated animals are increasing worldwide. They are best prevented by taking local advice. Injuries usually occur in places remote from medical care and may involve extensive trauma, haemorrhagic shock, and a high risk of bacterial contamination. First aid is resuscitation, control of bleeding and perforating injuries, intravenous fluid replacement, and rapid evacuation to hospital for emergency surgery and treatment of infection.

Venomous snakes

Bites by venomous snakes can cause death or permanent disability. This is largely an occupational/environmental hazard of agricultural workers and their children in rural areas of the tropic. Bites are commonly inflicted on the lower limbs and could be prevented by wearing protective footwear, by using lights while walking at night, and by sleeping off the ground or under a mosquito net.

Snake venoms are rich in toxic proteins that cause necrosis, shock, haemostatic disturbances, paralysis, rhabdomyolysis, and acute renal failure. Bites by Elapidae (cobras, kraits, mambas, coral snakes, Australian snakes, and sea snakes) may cause descending flaccid paralysis, starting with ptosis and progressing to respiratory paralysis. Some elapid venoms cause local necrosis, rhabdomyolysis and haemostatic disturbances. Bites by Viperidae (vipers, adders, and pit vipers—rattlesnakes, moccasins, lanceheads) can cause severe local swelling, bruising, blistering, and necrosis together with shock, consumptive coagulopathy, spontaneous systemic bleeding, renal failure, and, with some species, neurotoxicity.

First aid involves reassurance, immobilization of the whole patient, especially the bitten limb, rapid evacuation to the nearest hospital, and avoidance of dangerous traditional methods. When the necessary skills and equipment are available, pressure-immobilization should be applied immediately unless the possibility of a neurotoxic elapid bite can be excluded.

In hospital, specific antivenom (hyperimmune equine or ovine immunoglobulins) is given if there is evidence of systemic or severe local envenoming. Polyspecific antivenoms cover envenoming by medically important snakes in the geographical area for which they are intended. Early anaphylactic or pyrogenic reactions and late serum sickness antivenom reactions are common but not predictable by hypersensitivity tests. After the initial dose, the indication for more antivenom is failure of restoration of blood coagulability after 6 h, or progression of other signs of envenoming. Assisted ventilation, renal dialysis, or cardiovascular support may be required. Necrotic tissue requires surgical debridement. Signs of compartment syndrome may be misleading and fasciotomy is rarely justified.

Venomous fish

Many fish of temperate and tropical seas can inflict dangerous stings—stingrays, catfish, weevers, scorpionfish, stonefish, and lionfish. Prevention is by wearing foot protection when wading and avoiding contact with tropical reef fish. Immediate agonizing pain is alleviated by immersing the stung limb in uncomfortably hot but not scalding water (less than 45 °C). Erythematous swelling and necrosis may ensue with the risk of infection by marine bacteria. Stingray spines can cause fatal penetrating injuries. Systemic envenoming is uncommon. Stonefish antivenom is available

Poisonous aquatic animals

Ciguatera poisoning from eating tropical reef fish is prevalent in Pacific and Caribbean regions. Fish acquire polyether toxins from dinoflagellates. Acute gastroenteritis develops 1 to 6 h after ingestion, followed by neurotoxic and cardiovascular disturbances.

Tetrodotoxin poisoning is attributable to the Japanese delicacy ‘fugu’ (puffer fish). Neurotoxic symptoms caused by this sodium channel blocker develop 10 to 45 min after ingestion. Fatal respiratory paralysis may ensue 2 to 6 h later

Paralytic shellfish poisoning is caused by eating bivalve molluscs contaminated with tetrahydropurine neurotoxins from dinoflagellates. Neurotoxic symptoms appear within 30 min of ingestion, progressing to fatal respiratory paralysis within 12 h

Scrombroid poisoning results when bacterial decomposition of tuna and other dark-fleshed fish generates histamine. Anaphylactic-type symptoms develop within minutes to a few hours after ingestion.

Prevention is by avoiding scaleless (tetrodotoxic) fish, large reef fish (ciguatera-toxic), and shellfish when there is a red tide. Correct processing prevents scrombroid poisoning. Cooking does not destroy any of these toxins.

Venomous marine invertebrates

Cnidarians (jellyfish, stinging corals, sea anemones, etc.) have tentacles studded with stinging nematocysts. Lethal species are Indo-Australian box jellyfish, Irukandji, Portuguese man-o’-war (Physalia), and Chinese Stomolophus nomurai. Prevention is by observing warning notices on affected beaches, bathing in ‘stinger-resistant’ enclosures, or wearing protective clothing. Stings produce immediately painful irritant weals. Box jellyfish cause the most severe systemic symptoms: respiratory and cardiac arrest, generalized convulsions, and pulmonary oedema within minutes of the accident. ‘Irukandji’ syndrome is distinctive: severe persisting musculoskeletal pain, anxiety, trembling, headache, piloerection, sweating, tachycardia, hypertension, and pulmonary oedema starting about 30 min after stings by tiny cubomedusoids. Vinegar inactivates box jellyfish and Irukandji nematocysts. Hot water relieves the pain of Physalia stings. Box jellyfish antivenom is available in Australia.

Echinoderm (starfish and sea urchin) spines become embedded in waders’ feet, sometimes penetrating bones and joints. Pain is relieved by hot water. Systemic envenoming is rare but there is a risk of marine bacterial infection.

Molluscs—cone shells and small Australasian blue-ringed octopuses can cause fatal envenoming.

Access to the complete content on Oxford Medicine Online requires a subscription or purchase. Public users are able to search the site and view the abstracts for each book and chapter without a subscription.

Please subscribe or login to access full text content.

If you have purchased a print title that contains an access token, please see the token for information about how to register your code.

For questions on access or troubleshooting, please check our FAQs, and if you can''t find the answer there, please contact us.