Great Note About Venomous Species In Animals

 Venomous species occur in most phyla of marine animals. Their relative medical importance is increasing with the growing popularity of travel and of aquatic sports and with expanding ex­ploitation of marine resources. Recognition of these animals and knowledge of their habits minimize opportunities for injury.Most marine animal venoms appear to be pro­teins; however, quaternary ammonium com­pounds, epinephrine, 5-hydroxytryptamine., his­tamine, and other pharmacologically active compounds have been detected. Zoo Toxicologic properties of these venoms are too diverse for brief summary. Mechanisms of action for most species are poorly understood.


Jellyfish Stings

The pelagic coelenterates known as jellyfish belong to two main groups, the Portuguese men-of-war or blue-bottle of the class Hydrozoa and the “true” jellyfish of the class Scyphozoa. Medically important species occur in all oceans; however, more serious stings are reported |from Australian and south Asian waters. The venom apparatus consists of tentacles that may be up to 30 meters long and are thickly studded with highly specialized stinging capsules or nematocysts. Their primary function is capture and immobilization of food. Coelenterates never attack man; indeed, they are physically incapable of doing so. Injuries usually occur through contact with floating or stranded concentrates or their detached tentacles.

Such contact is followed by intense burning pain and development of linear, erythematous wheals that may progress to vesiculation. Muscular cramps, dyspnea, and nausea may be seen. Local necrosis may follow severe jellyfish stings. A systemic reaction clinically similar to anaphylactic shock may follow stings by sea wasps (Chiropsalmus and Chironex : death has occurred three to four minutes arte.’ contact. Irukandji sting, caused by the Australia:-, jellyfish Carukia barnesi, is characterized by a mild nettling rash followed after 10 to 60 minutes by sweating, cramps, severe myalgia, vomiting and, sometimes, cough with hemoptysis. Recovery occurs within a day or two.

If tentacles are clinging to the skin, they should not be palled or rubbed off, as this may discharge additional nematocysts. Prompt application of alcohol to the tentacle will inactivate the nema­tocysts. If alcohol is not available, the tentacles should be covered with sugar, salt, or dry sand and left alone 15 to 20 minutes before being scraped off. Local application of analgesic cream or oint­ment, preferably one containing an antihistamine, may give some relief. Systemic reactions have been successfully counteracted by epinephrine (0.5 to 1 ml. subcutaneously) plus 10 ml. intra­venously of calcium glauconite, antihista, artificial respiration, and oxygen. Morphine or meperidine may be required to control pair..

Cone Shell Stings.

Large marine snails of the genus Conus inflict injury with a harpoon-like tooth that can be rapidly extruded and is used for capture of prey as well as defense. Nearly all injuries are seen in shell collectors. Mild cases show only local symptoms resembling those of wasp stings. In severe cases, initial pain is fol­lowed by numbness, paresthesia, paresis be­ginning in the region of the injury and occasionally spreading to involve the entire skeletal muscula­ture, sensation of constriction of the chest, dys­phagia, visual disturbances, and collapse. Fatal­ities are on record, nearly all of them ascribed to the large species, C. geography, widely distrib­uted in the warmer parts of the Pacific and Indian Oceans.The active principle of cone shell venom has not been identified, and treatment of stings is symptomatic.

Miscellaneous Venomous Invertebrates.

Spines of sea urchins cause painful injuries, occasionally accompanied by giddiness and muscular palsies lasting several hours. A species of spiny Australian starfish inflicts a wound followed by bouts of vomit­ing lasting several days. Various sessile coelen­terates coelen­terates such as hydroids, sea anemones, and stinging corals cause nettle-like stinging, some­times with zosteriform hemorrhagic lesions and necrosis. Abdominal cramps, chills, diarrhea, and leukocytosis with eosinophilia may accompany severe stings. There is no specific treatment for any of these envenomations.

Venomous Fishes

Stonefish (Synanceia), scorpionfish (Scorpaena, lionfish (Pterois), weever fish (Trachinus). and related species have venom glands associated with spines, especially those of the dorsal fin. Except for the greater weever, these arc shallow-water fish particularly common about reefs, where they lie partly buried or concealed in crevices. Here they are apt to be accidentally touched or trodden upon. In open water the fish may adopt a more active defense, swimming so that the venomous spines are presented to an enemy. Skin divers and aquarium keepers have been injured under such circumstances. Fishermen may be injured when removing the fish from nets or traps. Similarity of symptoms and of venom activity in laboratory animals suggests common or similar active principles in their venoms. Synanceia verrucosa, found from Oceania to the east coast of Africa, appears to be the most dangerous member of this group.

Following injury by spines of these fishes, there is local pain that tends to spread and is often followed by hypesthesia or paresthesia at the site of puncture. Victims invariably describe the pain as almost unbearable, and it is regularly accom­panied by hyperactivity often manifest by rolling about on the ground, There is severe local swell­ing, sometimes with formation of blisters and sloughing. Profuse sweating, dyspnea,, hypoten­sion, cyanotic, and collapse are seen especially with Synanceia stings; death may occur within an hour. Those who survive a severe sting may complain of weakness, dyspnea, and muscular aches for several weeks.

Ligature, incision, and suction as recommended for snakebite have some value as first aid if done within 15 minutes. Immersion of the injured site in hot water helps relieve pain.Antivenin for Synanceia is available from Com­monwealth Serum Laboratories of Australia: it may be expected to have some effect in stings by related species of fishes. The initial intra­muscular or intravenous dose of 2 ml. may be repeated in severe cases. Infiltration of the wound with emetine hydrochloride solution ’65 mg. per millilitre) is recommended if antivenin is not available.

Stingrays are widely distributed in warm coastal waters, including mouths of rivers: one genus is restricted to freshwater. There are about 30 med­ically important species; the larger ones are 8 to 10 feet long, and weigh more than 100 pounds. Venom-secreting tissue is in the grooves and sheaths of barbed bony spines on the dorsum of the tail; in large species of rays, the spine maybe 35 to 40 cm. long. Stingrays typically bury themselves in sand or mud, where they may be stepped upon or grazed by persons diving.

The fish lashes with its tail, driving the sting into its vic­tim. Stings of large rays can readily penetrate the abdominal or thoracic wall. The wound is a puncture or laceration often surrounded by a zone of blanching for the first 30 minutes or so; later the area becomes hyperaemia and eczematous. Pain is severe, and sweating, nausea, weakness, and syncope are common.

Muscular twitching, convul­sions, irregular respiration, and cardiac arrhyth­mia indicate severe poisoning. Of 1097 stingray injuries reported in the United States during a five-year period, 62 patients required hospitali­zation, and two deaths resulted.Ir­rigation with salt water and removal of any fragments of the sting sheath that can be seen. This is followed by soaking in hot water for 30 tc Hi minutes, administration of analgesics, and tetanus prophylaxis. Injuries by large rays, particular”‘ when the chest or abdomen has been penetrate,., require surgical management. There are no spe­cific pharmacologic antagonists to stingray venom,, nor is antivenom available.

by Abdullah Sam
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