Animal bone cancer in jaw

Definition

Humans can be injured by the bites or stings of many kinds of animals, including mammals such as dogs, cats, and fellow humans; arthropods such as spiders, bees, and wasps; snakes; and marine animals such as jellyfish and stingrays.

Description

Mammals

In the United States, where the dog population exceeds 50 million, dogs surpass all other mammals in the number of bites inflicted on humans. However, most dog-bite injuries are minor. A telephone survey of U.S. households conducted in 1994 led researchers to estimate that 3,737,000 nonmedically treated dog bites occurred in the United States that year, versus 757,000 that were medically treated. Studies also show that most dog bites are from pets or other dogs known to the victim, that males are more likely than females to be bitten, and that children face a greater risk than adults. Each year, about 10-20 Americans--mostly children under 10 years old--are killed by dogs.

Dog bites resulted in an estimated 334,000 emergency-room visits annually throughout the United States in 1992-94. More than half of the bites seen by emergency departments originated in the home. Children under 10 years old were more likely than older people to visit an emergency room for bite treatment, especially boys 5-9 years old. Children under 10 years old were also much more liable to be bitten on the face, neck, and head. Nearly all of the injuries suffered by the emergency-room patients were of "low severity," and most were treated and released without being admitted to hospital or sent to another facility.

Although cats are found in nearly a third of U.S. households, cat bites are far less common than dog bites. According to one study, cats inflict perhaps 400,000 harmful bites in the United States each year. The tissue damage caused by cat bites is usually limited, but they carry a high risk of infection: whereas the infection rate for dog bite injuries is 15-20%, the figure for cats is 30-40%. The typical bite victim is a young girl playing with a pet.

Bites from mammals other than dogs and cats are uncommon, with one exception--human bites, of which there are approximately more than 70,000 a year in the United States. Because the human mouth contains a multitude of potentially harmful microorganisms, human bites are more infectious than those of any other animal.

Arthropods

Arthropods are invertebrates belonging to the phylum Arthropoda, which includes insects, arachnids, crustaceans, and other subgroups--more than 700,000 species in all. The list of arthropods that bite or sting humans is long and encompasses lice, bedbugs, fleas, mosquitoes, black flies, ants, chiggers, ticks, centipedes, scorpions, and other creatures. Spiders, bees, and wasps are three kinds of arthropod that people often encounter.

In the United States, only two kinds of venomous spider are truly life threatening: widow spiders and brown (violin or fiddle) spiders. The black widow, which is found in every state but Alaska, is probably the most infamous widow spider. It prefers dark, dry places such as barns, garages, and outhouses, and also lives under rocks, logs, and so forth. Disturbing a female black widow or its web may provoke a bite. Brown spiders also prefer sheltered places, including clothing, and may bite if disturbed.

Bees and wasps

Bees and wasps will sting to defend their nests or if they are disturbed. Species common to the United States include honeybees, bumblebees, yellow jackets, bald-faced hornets, brown hornets, and paper wasps. Fifty or more Americans a year die after being stung by a bee, wasp, or ant, but almost all of those deaths are the result of allergic reactions, not exposure to the venom itself.

Snakes

Venomous snakes--of which there are 20 species in the United States--are found in every state except Maine, Alaska, and Hawaii. Each year about 8,000 Americans fall victim to a venomous snakebite, but no more than about 15 die, mostly from rattlesnake bites.

The venomous snakes of the United States are divided into two families, the Crotalidae (pit vipers) and the Elapidae. Pit vipers, which take their name from the small heat-sensing pit that lies between each eye and nostril, are responsible for about 99% of the venomous snakebites suffered by Americans. Rattlesnakes, copperheads, and cottonmouths (also called water moccasins) are pit vipers. This family of snakes delivers its venom through two long, hinged fangs in the upper jaw. Some pit vipers carry a potent venom that can threaten the brain and spinal cord, but the venom of others, such as the copperheads, is less harmful.

The Elapidae family includes two kinds of venomous coral snakes indigenous to the southern and western states. Because coral snakes are bashful creatures that come out only at night, they almost never bite humans, and are responsible for perhaps only 25 or so bites a year in the United States. Coral snakes also have short fangs and a small mouth, which lessens the risk of a bite actually forcing venom into a person's body. However, their venom is quite poisonous.

Marine animals

Several varieties of marine animal bite or sting. Jellyfish and stingrays are two kinds that pose a threat to Americans who live or vacation in coastal communities.

Causes & symptoms

Mammals

The typical dog bite results in a laceration, tear, puncture, or crush injury. Infected bites usually cause pain, cellulitis (inflammation of the connective tissues), and a pus-filled discharge at the wound site within 8-24 hours. Most infections are confined to the wound site, but many of the microorganisms in dogs' mouths can cause systemic and possibly life-threatening infections such as bacteremia and meningitis, especially among victims who suffer from acquired immunodeficiency syndrome (AIDS) or another health problem that increases their susceptibility to infection. Rabies is rare among pet dogs in the United States, most of which have been vaccinated against the disease. Tetanus is also rare.

The mouths of cats and dogs contain many of the same microorganisms. Cat scratches and bites are also capable of transmitting the Bartonella henselae bacterium, which can lead to cat-scratch disease, an unpleasant but usually not life-threatening illness.