Home > Encyclopedia of Nursing & Allied Health > Bites and Stings

Definition

People can be injured by the bites or stings of many 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

DOGS. In the United States, where the dog population exceeds 50 million, dogs surpass all other mammals in the number of bites inflicted on humans. Most come from family pets or other dogs known to the victim. Fortunately, most dog-bite injuries are minor. A 1994 telephone survey of American households indicated that there were 3,737,000 dog bites that did not require medical attention in the United States during that year, and 757,000 that did. Men and boys are more likely to be bitten than girls or women; not surprisingly, children face a greater risk than adults. Each year, about 10–20 Americans, mostly children under 10 years of age, are killed by dogs.

In the United States, dog bites send an estimated 340,000 people to the emergency room each year. Children under 10 are more likely than older people to need immediate medical treatment; this is especially true for boys between five and nine. Children under ten were also much more likely to be bitten on the face, neck, and head. Few of the injuries suffered by people seeking emergency treatment were serious; most patients were treated and released without being admitted or referred to another facility.

CATS. Although cats are found in nearly a third of American households, their 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. Cat bites typically cause less tissue damage, but they carry a higher risk of infection (30-40%) than dog bites (15-20%). Young girls are the most likely to be bitten by cats.

HUMANS. There are approximately 70,000 human bites each year in the United States. They can be just as serious a medical problem as a bite from an animal. Because the human mouth contains a multitude of potentially harmful microorganisms, these tend to become have a higher infection rate than those inflicted by animals.

Arthropods

Arthropods are invertebrates such as insects, arachnids, crustaceans, and other subgroups of the phylum Arthropoda—a group that encompasses more than 700,000 species. The list of arthropods that bite or sting is extensive and includes lice, bedbugs, fleas, mosquitoes, blackflies, ants, chiggers, ticks, centipedes, scorpions, and other creatures. Spiders, bees, and wasps are the three that people encounter most often.

SPIDERS. In the United States, only two kinds of venomous spider have a truly life-threatening bite: black widow spiders and brown recluse 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 and logs. Disturbing a female black widow or her web may provoke a bite. Red widow spiders are far more rare, but can be found in parts of Florida; their sting is also quite venomous. Brown recluse 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. More than 50 Americans die each year after being stung by a bee, wasp, or fire ant. Almost all of those deaths are caused by allergic reactions to the venom, not by its toxicity.

Snakes

There are 20 species of venomous snakes in the United States; they're found in every state except Maine, Alaska, and Hawaii. Each year about 8,000 Americans receive a venomous snakebite, but no more than about 15 die; most of the deaths are from rattlesnake bites.

The venomous snakes of the United States are divided into two families: Crotalidae (pit vipers) and 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. The group includes rattlesnakes, copperheads, and cottonmouths (also called water moccasins). This type of snake delivers its venom through two long, hinged fangs in the upper jaw. Some pit vipers carry a potent, fast-acting venom that can damage the brain and spinal cord. The venom of others, such as the copperheads, is less harmful.

The Elapidae include 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 only about 25 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 through the skin and subcutaneous tissues into muscles or veins. However, if ingested, their venom is quite poisonous.

Marine animals

Several varieties of marine animal bite or sting, including sharks, jellyfish, stingrays, anemones, and even a few types of coral. Although only a few have venom powerful enough to kill, they can inflict painful injuries. As with spider and bee stings, allergic individuals can also have anaphylactic reactions to these bites.

Causes and symptoms

Mammals

DOGS. A typical dog bite results in a laceration, 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 microorganisms in dogs' mouths can cause systemic and possibly life-threatening infections such as sepsis and meningitis, especially among people with compromised immune systems that decrease their resistance to infection. Rabies is rare among pet dogs in the United States, most of which have been vaccinated against the disease. Tetanus is also a rare complication.

CATS. Cat scratches and bites can transmit the Bartonella henselae bacterium, which can lead to catscratch disease, an uncommon and unpleasant but not usually life-threatening illness. The mouths of cats and dogs contain many of the same microorganisms, and many of the same types of infections can result.

Cat bites are mostly found on the arms and hands. Sharp cat teeth typically leave behind a deep puncture wound that can reach muscles, tendons, and bones, which are vulnerable to infection because of their comparatively poor blood supply. This is one reason why cat bites are much more likely than dog bites to become infected. People are also less inclined to give cat bites immediate medical attention, increasing the risk that infection will set in. Infected cat scratches on fingers or toes, in fact, have been known to spread inward to the bone, and result in the need for amputation of the digit.

HUMANS. Although children often bite other children, these bites are hardly ever severe. Most humans bites that require medical attention result from fights (raising the possibility of domestic or child abuse), sexual activity, medical and dental treatment, and seizures. They can transmit a wide range of dangerous diseases, including hepatitis B, syphilis, tuberculosis, and HIV.

Human bites fall into two categories: occlusional (true) bites and clenched-fist injuries. The former present a low risk of infection. The latter, which are very infectious and can permanently damage the hand, usually result when a fist hits teeth during a fight. People often wait before seeking treatment for a clenched-fist injury, with the result that about half of such injuries are infected by the time they are seen by a medical professional.

Arthropods

SPIDERS. People do not always feel a black widow's bite. The first (and possibly only) evidence that a person has been bitten may be a mild swelling of the injured area and two red puncture marks showing where the spider's fangs entered the skin. Within a short time, however, some victims begin to experience severe muscle cramps and rigid abdominal muscles. Other possible symptoms include excessive sweating, nausea, vomiting, headaches, and vertigo as well as breathing, vision, and speech problems.

A brown recluse spider's bite can lead to necrotic arachnidism, in which the tissue in an area of up to several inches around the bite becomes necrotic, producing an open sore that can take months or years to heal completely. About 40% of all bites are accompanied by more severe symptoms: fever, chills, edema, nausea, vomiting, dizziness, muscle and joint pain, and a measles-like rash. The bite becomes hard and inflamed, and may turn gangrenous. In most cases, fortunately, the bite simply produces a hard, painful, itchy, and discolored area that heals without treatment in two to three days.

BEES AND WASPS. The familiar symptoms of bee and wasp stings include pain, redness, swelling, and itchiness in the area of the sting. Multiple stings can have much more severe consequences. If an allergic reaction occurs, there can be life-threatening symptoms of facial swelling, throat closure, tongue swelling, and airway blockage within a very short time.

Snakes

Many pit viper and coral snake bites (20–60%) fail to poison (envenom) their victims, or manage to introduce only a small amount of venom into the victim's body. The wounds, however, can still become infected by the harmful microorganisms that snakes carry in their mouths.

Venomous pit viper bites usually begin to swell within 10 minutes and are sometimes painful. Other symptoms include edema at the wound site, skin blisters, discoloration, weakness, sweating, nausea, faintness, dizziness, bruising, and tender lymph nodes. Symptoms of severe poisoning include tingling in the scalp, fingers, and toes, muscle contractions, an elevated heart rate, rapid breathing, large drops in body temperature and blood pressure, vomiting of blood, and coma.

Coral snake bites are painful but may be hard to see. After some time has passed, a bitten person begins to experience the effects of the venom, which include tingling at the wound site, weakness, nausea, vomiting, excessive salivation, and irrational behavior. Nerves in the head and neck can become paralyzed for six to 14 days, causing double vision, difficulty swallowing and speaking, respiratory failure, and other problems. Six to eight weeks may be needed before normal muscular strength is regained.

Marine animals

JELLYFISH. Jellyfish venom is delivered by barbs called nematocysts that are located on the creature's tentacles. They sting anyone who brushes up against them, causing a red lesion that is instantly painful and itchy. The pain can continue up to 48 hours. Severe cases may lead to necrosis, muscle spasms and cramps, vomiting, nausea, diarrhea, headaches, excessive sweating, and other symptoms. In rare instances, cardiorespiratory failure results.

STINGRAYS. Stingrays carry their venom in their tail spines, which can inflict deep puncture wounds. If, as often happens, pieces of spine become embedded in the wound, an infection can result. Most people are injured by a stingray when they inadvertently step on one that's resting, and are lashed in the ankle by its tail. Stingray venom produces immediate, excruciating pain that lasts several hours. Sometimes the victim suffers a severe reaction, including vomiting, diarrhea, hemorrhage, a drop in blood pressure, and cardiac arrhythmia.

Diagnosis

Mammals

DOGS. Gathering information on the circumstances of a dog attack is a crucial part of bite treatment. Among other things, medical professionals need to know when the attack occurred (the chances of infection increase dramatically if the wound has been left untreated more than eight hours) and what led to the attack (unprovoked attacks are more likely to be associated with rabid animals). The patient's general health must also be assessed, including tetanus immunization history and possible allergies to medication.

A physical examination demands careful scrutiny of the wound, with special attention to possible bone, joint, ligament, muscle, tendon, nerve, or blood-vessel damage that may have been caused by deep punctures or severe crush injuries. Experts advise that serious hand injuries should be evaluated by a surgeon who specializes in such cases. Most of the time, laboratory tests to identify the microorganisms in bite wounds are ordered only if infection is present. X rays and other diagnostic procedures may also be necessary.

CATS. The diagnostic procedures used for dog bites also apply to cat bites.

HUMANS. Anyone who has received a human bite must be tested for hepatitis B and other diseases; ideally, the biter should be tested as well. Clenched-fist injuries require evaluation by a hand surgeon. Because many people will deny having been in a fight, medical professionals are advised to always consider lacerations over the fourth and fifth knuckle—a typical clenched-fist injury—to be evidence of a bite wound, no matter what an individual says. Medical professionals should also look for other indications of spousal or child abuse when evaluating human bites.

Arthropods

SPIDERS. Spider bites always require medical attention, although victims are often not aware that they've been bitten. To make matters worse, unless the spider is seen biting the victim, identifying which species is responsible is difficult. If possible, the spider should be captured and taken to the emergency room or doctor's office for identification.

Snakes

Diagnosis relies on a physical examination of the victim, information about the circumstances of the bite, and a look at the snake itself (if it can safely be brought in for identification). Blood tests and urinalysis supply important data on the victim's condition. Chest x rays and EKG (electrocardiogram) may also be necessary.

Treatment

Mammals

DOGS. Minor dog bites can be treated at home. The American Academy of Family Physicians recommends gently washing the wound with soap and water and then applying pressure to the injured area with a clean towel to stop the bleeding. Next, apply antibiotic ointment and a sterile bandage to the wound. To reduce swelling and fend off infection, ice should be applied and the injured area kept elevated above the level of the heart. The wound should be cleaned and ointment reapplied twice a day until healing is complete.

Any dog bite that does not stop bleeding after 15 minutes of pressure must be seen by a medical professional. The same is true for bites that are deep or gaping; for bites to the head, hands, or feet; and for bites that may have broken a bone, damaged nerves, or caused a major injury of another kind. Bite victims must also watch for signs of infection: fever, redness, swelling, warmth, increased tenderness, and pus at the wound site. Diabetics, people with AIDS or cancer, individuals who have not had a tetanus shot in five years, and anyone else who has a medical problem that can increase susceptibility to infection should seek medical treatment no matter how minor the bite appears.

Medical treatment of dog bites involves washing the wound with an anti-infective solution. Dead and/or damaged tissue may be need to be removed, and any person whose tetanus shots are not up to date should receive a booster. Some wounds are left open and allowed to heal on their own, from the inside out, while others require stitches (stitching may be delayed a few days if infection is a concern). Many emergency departments prescribe antibiotics for all people with dog bites, but some researchers suggest that antibiotics are usually unnecessary and should be limited to those whose injuries or other health problems make them likely candidates for infection. A follow-up visit after one or two days is generally required for anyone who has received bite treatment.

Other than death by trauma, the biggest threat from a dog bite is rabies (although no one in the United States has contracted rabies from a dog bite for many years). Dogs who bite people should be contained and tested for rabies, unless the owner can prove the animal has been immunized. If this is not possible, a rabies vaccine series for the victim is effective if administered within two days of the bite.

CATS. Because of the high risk of infection, people who are bitten by a cat should always see a doctor. Cat scratches do not require professional medical treatment unless the wound appears infected or the victim has a weakened immune system. Cats, like dogs, can also transmit rabies, and cats that inflict a bite should be contained and tested for rabies, unless their immunization history is known.

Medical treatment for cat bites generally follows the procedures used for dog bites. Experts advise, however, that cat-bite wounds should always be left open (not stitched) to prevent infection. Persons bitten by cats are also more likely to receive antibiotics as a preventive measure.

HUMANS. Human bites should always be examined by a doctor. Such bites are usually treated with antibiotics and left open because of the high risk of infection. A person who has been bitten may also require immunization against hepatitis B and other diseases. A follow-up visit is required after an occlusional bite. Persons who are being treated for a clenched-fist injury will require a daily follow-up examination for three to five days.

Arthropods

SPIDERS. Brown recluse spider bites require immediate medical attention. Put an antiseptic on the bite, apply ice to reduce swelling, then get the patient to a doctor as quickly as possible. Analgesics, antihistamines, and a tetanus shot are the standard course of treatment, along with erythromycin and other antibiotics to combat infection. If necrosis results, the affected areas may need debridement.

Experimental treatment includes steroids to combat the hemolysis that can result from the spider venom. Surgical excision of the bite once eschar has developed may be an effective way to remove the venom and prevent further tissue damage. Interestingly, the leprosy drug dapsone has shown some promise in this area, and may prevent the need for surgery. Hyperbaric oxygen treatments may also restore blood flow to dying tissue. A

promising antivenin has been developed, but it's not yet available for clinical use.

Black widow spider bites also need a doctor's care. Apply ice to the bite, then take the patient to an emergency room. If necessary, antivenin is administered. In less severe cases, the symptoms are treated with calcium and muscle relaxants for spasms, along with drugs to lower blood pressure.

BEES AND WASPS. Most stings can be treated at home. A stinger can be scraped off the skin with a razor blade, fingernail, credit card, or piece of paper; using tweezers may push more venom out of the venom sac and into the wound. The area should be cleaned and covered with an ice pack. Aspirin and other pain medications, oral antihistamines, and calamine lotion can relieve the pain, itching, and swelling.

The biggest risk from a bee sting is anaphylactic reaction to bee or wasp venom. This requires immediate medical attention. The danger signs, which usually begin within minutes after a sting, (but may not appear for several hours) include nausea, chest pain, hives (both internal and external), abdominal cramps, diarrhea, and difficulty swallowing or breathing. These last symptoms can be life threatening if not treated immediately. Patients with a history of allergic response to stings are prescribed a self-injecting kit of adrenaline and anti-histamine.

Snakes

Although most snakes are not venomous, any snakebite should immediately be examined at a hospital. While waiting for emergency help to arrive, the victim should wash the wound site with soap and water, and then keep the injured area still and at a level lower

than the heart. Ice should never be used on the wound, and no attempts should be made to extract the venom. Making a cut at the wound site is also dangerous. It is important to stay calm and wait for emergency medical aid.

When a snakebite victim arrives at a hospital, the medical staff must determine, if they can, whether the bite was inflicted by a venomous snake and, if so, how much venom the person received. Careful monitoring helps resolve doubtful cases. Fortunately, the effects of some snakebites can be counteracted with antivenin. Minor rattlesnake envenomations can be successfully treated without antivenin, as can copperhead and water moccasin bites. However, coral snake and the more dangerous rattlesnake envenomations require antivenin. Other treatment measures include antibiotics to prevent infection and a tetanus booster injection.

Marine animals

JELLYFISH. To stop envenomation from tentacles that cling to skin, various substances should be applied, depending on the species that delivered the sting. Vinegar, baking soda, meat tenderizer (papain), and other substances will neutralize nematocysts. Applying the wrong substance, however, can cause the nematocysts to fire again, increasing the dose of venom and the degree of pain for the victim. Once the tentacles have been neutralized, they can be scraped off, saved, and given to medical personnel for identification and diagnosis. Ice, topical anesthetics, antihistamines, steroids, and a tetanus booster can prevent further complications. As with bee stings, allergic reactions may occur, requiring emergency medical care.

STINGRAYS. Stingray wounds should be washed with salt water and then soaked in very hot water for 30–90 minutes to neutralize the venom. Afterwards, the wound should be examined by a doctor to ensure that no pieces of spine remain.

Alternative treatment

Arthropods

Several alternative self-care approaches are used to treat bee, wasp, and other minor arthropod stings, including aromatherapy, ayurvedic medicine, flower remedies, herbs, homeopathy, and nutritional therapy. The efficacy of these treatments has not been proven, however, and if alternative therapy delays the administration of traditional medical attention for dangerous bites or stings the risk of severe consequences increases.

Prognosis

Mammals

It is important to realize that apparently even minor bites can have serious consequences, and that prompt treatment is the key to a good outcome. Infected bites may require hospitalization and can be fatal if neglected. Surgery may be needed for severe bites.

Arthropods

SPIDERS. Even without treatment, adults tend to recover from black widow bites after two to three days. The risk of death, though rare, is highest for very young children, the elderly, and people with high blood pressure.

BEES AND WASPS. The pain and other symptoms of a bee or wasp sting normally fade after a few hours. People who are allergic to such stings, however, can experience a severe and occasionally fatal reaction.

Snakes

A snakebite victim's chances of survival are excellent if medical aid is rendered in time. Some bites, however, result in amputation, permanent deformity, or loss of function in the injured area.

Marine animals

STINGRAYS. Stingray venom only rarely kills its human victims.

Health care team roles

Persons trained in first aid provide initial support. Emergency medical technicians provide life support and transportation to medical facilities. Physicians trained in emergency or environmental medicine supervise treatment of bite victims. Registered nurses support, treat, and care for patients in emergency rooms and other hospital departments. Surgeons debride and repair serious bite wounds. Laboratory technicians process fluid and tissue specimens. Pathologists interpret test results. Physical therapists provide therapeutic services during the recovery period.

Prevention

Mammals

DOGS. The risk of a dog bite can be reduced by avoiding sick or stray dogs, staying away from dogfights (people often get bitten when they try to separate the animals), and not provoking or upsetting dogs while they are sleeping, eating, or tending their puppies. Infants and young children must never be left alone with a dog. Pit bulls, rottweilers, and German shepherd dogs—breeds that caused nearly half of all fatal dog attacks in the United States between 1997 and 2000—are potentially dangerous pets in households where children live or visit. All dog breeds benefit from obedience training and spaying or neutering to lessen the chances of aggressive behavior.

CATS. Warn children to stay away from strange cats and to avoid rough play and other behavior that can anger cats and cause them to bite.

Arthropods

SPIDERS. Common-sense precautions include exercising caution when clearing webs out of garages, outhouses, and other places favored by venomous spiders; keeping one's hands away from places where spiders may be lurking; and, when camping or vacationing, checking clothing, shoes, and sleeping areas.

BEES AND WASPS. When outdoors, avoid bee and wasp nests, and don't eat sweet food or wear bright clothing, perfumes, or fragranced cosmetics that attract bees and wasps.

Emergency medical kits containing self-injecting epinephrine to counter anaphylactic shock are available for people with a history of allergic response to insect stings; these should be carried with them at all times. People who suspect they are allergic should consult an allergist about immunotherapy shots that can build up resistance to bee and wasp venom.

Snakes

Mowing the lawn, trimming hedges, and removing brush from the yard discourages snakes from living close to homes. Use tongs to move brush, lumber, and firewood in case snakes are lying beneath them. Similarly, golfers should never use their hands to retrieve golf balls from a water hole, since snakes can be hiding in the rocks and weeds. Caution is also necessary when walking through weedy or grassy areas, and children should be prevented from playing in weedy, vacant lots and other places where snakes may live. Leather boots and long pants offer hikers and campers some protection from bites. Approaching a snake, even a dead one, can be dangerous, for recently killed snakes can still inflict a venomous bite if there is contact with the fangs.

Marine animals

JELLYFISH. Obey posted warning signs at the beach. Also, since jellyfish tentacles are transparent and can be up to 120 ft (36.5 m) long, great caution must be exercised whenever a jellyfish is sighted nearby.

STINGRAYS. Shuffling while walking through shallow areas that may be inhabited by stingrays will disturb the water, causing the animal to move before it can be stepped on.

L. Fleming Fallon, Jr., M.D., Ph.D.

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KEY TERMS

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Antibiotics—Substances used to fight bacteria that cause infection.

Antibodies—Substances in the blood created by the body to combat infection.

Antihistamines—Drugs that treat allergic reactions by acting against a substance called histamine, which the body releases as part of its immune response.

Antivenin—An antitoxin to a specific animal venom. Antivenin is extracted from the blood serum of horses (or other animals) that have been immunized against the toxin.

Blood serum—The component of blood plasma that remains after coagulation.

Debridement—Removal of dead and/or damaged tissue.

Edema—Excessive fluid buildup in a body tissue.

Eschar—Sloughed off dead tissue.

Hemolysis—Breakdown of red blood cells.

Necrosis—Dead skin, muscle, bone, or other tissue in the body caused by insufficient blood flow.

Pus—A thick yellowish or greenish fluid composed of the remains of dead white blood cells, pathogens, and decomposed cellular debris; a definite sign of infection.

Sepsis—A serious systemic infection caused by bacteria that have entered the bloodstream through a wound.

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