StoryImage( ‘/Images/Story//Auto-img-118366270232069.jpg’, ‘Photo courtesy of www.lilly.com‘, ‘The beaded lizard or gila monster is the only venomous lizard native to this country.‘);
StoryImage( ‘/Images/Story//Auto-img-11836627551701.jpg’, ‘Photo by Dr. Robert A. Hedeen’, ‘The rattlesnake is the most dangerous venomous animal in the U.S. Note the dark pit below the eye identifying it as a pit viper.‘);
Many people wonder from time to time how really dangerous some of the venomous animals they may encounter as they travel about are. Fortunately, if you dont wander far from the Rock River Valley, you have little to worry about. In our area, the only animals with potent venom are the pygmy rattlesnake and the black widow and brown recluse spiders, and they are very rare. Of course, if a person happens to be hyper- allergic to the venom injected when stung by a bee or wasp, a serious medical condition can develop.
However, if a person travels to different parts of the country, he may come in contact with five groups of dangerously venomous animals: pit vipers, coral snakes, lizards, scorpions, and an abundance of black widows and brown recluses.
Any attempt to classify how relatively dangerous each of these groups are results in qualifications, but it can be asserted that the bites of rattlesnakes are probably responsible for more deaths, more hospitalizations, and more crippling injuries than any other animal in the United States. A brief discussion of each of the five groups is as follows:
Pit Vipers: This group of snakes includes the rattlers, copperheads, cottonmouths, and the massasauga. The group is named for a sensory pit that is located halfway between the tip of the head and each eye. Rattlesnakes are by far the more numerous of the pit vipers with 32 different species having been described. Snake venom is modified saliva containing a combination of some 26 different enzymes, the combination of which determines if the poison attacks the circulatory system (hemotoxic) or the nervous system (neurotoxic). Pit viper venom is hemotoxic in nature and is injected in a large amount through hypodermic, needle-like fangs. At he present time, there is considerable debate about how to treat a bite by a pit viper. Some experts say the old cut-and-suck method after a ligature is applied between the bite and the heart does more harm than good. Others say the injection of an antivenin made from horse serum is the only way to go, but serious reactions to the horse serum are common.
In general, the bite of a copperhead or a cottonmouth is less serious than that of a rattlesnake because of a different combination of the enzymes making up the toxic injection.
Coral Snakes: These relatives of the cobra and krait include both the eastern and the Arizona coral snake. The venom of the eastern species is considerably more potent than that of its western cousin and has resulted in some deaths. No deaths have ever been reported from the bite of an Arizona or western coral. Coral snake venom is neurotoxic in nature, affecting the nervous system including the brain. Corals do not have hollow fangs as do the vipers, so the venom is slowly injected as it drains down grooves in the front teeth. If bitten by a coral snake, pull it loose as soon as possible, and get to a hospital as quickly as possible. Antivenin is the only treatment available for the bite of a coral snake.
Scorpions: The sting of a scorpion (they dont bite) is extremely painful and is delivered by a spine at the end of a tail-like abdomen. Two claw-like appendages hold the victim while the abdomen is whipped over and the sting inflicted. The only really dangerous scorpion found in the U. S. is the Durango scorpion that is confined to southern Arizona and New Mexico, but no deaths have been reported since the 1950s. Scorpion venom is neurotoxic in nature.
Gila Monster: The beaded lizard or gila monster is the only venomous lizard in this country and is found in the west in Arizona, New Mexico, southern Nevada and Utah. These lizards are rare, and bites of human are even rarer. They have grooved teeth down which its hemotoxic venom flows. No antivenin is available, and treatment is symptomatic. Human deaths resulting solely from the bite of a gila monster have never been documented
Black Widow and Brown Recluse Spiders: As noted, these spiders are uncommon in northern Illinois, but occasionally one is encountered. The venom of the black widow is a powerful neurotoxin affecting various organs of the body. Some years ago, at the Armys Medical Field Service School, my colleague Dr. (Major) Hugh Keegan and I tested the potency of black widow venom on white rats. We found the spiders venom wasdry weight for dry weightroughly 40 times as potent as that of a diamondback rattlesnake. An antivenin for black widow venom is available, and no human deaths from the bite of a widow have been recorded in the last several years.
The venom of the brown recluse or fiddleback spider has a different effect. The combination of enzymes in it destroys cells in the area around the site of the bite, resulting in necrosis of tissue. An ulcerated area results that may be difficult to heal, and skin grafting may eventually be required. An antivenin for brown recluse venom is under development. But, not to worry, the average persons chance of encountering one of these venomous critters is very slim, and being envenomated by one is even slimmer.
Dr. Robert Hedeen is a former resident of Marylands eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.
from the July 5-10, 2007, issue