Bites and stings
Humans can be injured by the bites or stings of many kinds of animals, including dogs, cats, and fellow humans; arthropods such as spiders, bees, and wasps; snakes; and marine animals such as jellyfish and stingrays.
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. Each year, about 10-20 Americans, mostly children under 10 years old, are killed by dogs.
Cat bites are far less common than dog bites. The tissue damage caused by catbites is usually limited, but they carry a higher risk of infection. The infection rate for dog bites is 15-20%. For cats it is 30-40%.
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 potentiallyharmful microorganisms, human bites are more infectious than those of any other animal.
There are more than 700,000 species of arthropods, a group that includes insects, spiders, and crustaceans (crabs). The list of these animals that bite orsting humans is long and encompasses lice, bedbugs, fleas, mosquitoes, blackflies, ants, chiggers, ticks, centipedes, scorpions, spiders, bees, and wasps.
In the United States, only two kinds of venomous spider are truly life threatening: black widow spiders and brown (violin or fiddle) spiders. The black widow, which is found in every state but Alaska, prefers dark, dry places suchas barns, garages, and outhouses. Brown spiders also prefer sheltered places.Both may bite if disturbed.
Bees and wasps sting to defend their nests or if they are disturbed. Fifty ormore 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 tothe venom itself.
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 are bitten by a venomous snakes, but no more than about 15 die, mostlyfrom rattlesnake bites.
Several varieties of marine animal bite or sting. Jellyfish and stingrays pose the most threat to Americans who live or vacation in coastal communities.
Bites and stings vary in appearance depending on what animal caused the bite.The typical dog bite is 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 some of the microorganisms in dogs' mouths can cause life-threatening infections such as bacteremia and meningitis.
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.
Humans bites result from fights, sexual activity, medical and dental treatment, and seizures. Children often bite other children, but those bites are hardly ever severe. Human bites are capable of transmitting dangerous diseases, including hepatitis B, syphilis, and tuberculosis.
People do not always feel the black widow spider's bite. The sign may be a mild swelling of the injured area and two red puncture marks. Within a short time, however, some victims experience severe muscle cramps and rigidity of theabdominal muscles. Other possible symptoms include excessive sweating, nausea, vomiting, headaches, and vertigo as well as breathing, vision, and speechproblems.
A brown spider's bite can cause tissue in an area of up to several inches around the bite to die, producing an open sore that can take months or years todisappear. In most cases, however, the bite simply produces a hard, painful,itchy, and discolored area that heals without treatment in 2-3 days. The bitemay also be accompanied by a fever, chills, nausea and vomiting, dizziness,muscle and joint pain, and a rash.
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.
Many venomous snake bites fail to poison the victim, or introduce only a small amount of venom into the victim's body. The wounds can still become infected by microorganisms that snakes carry in their mouths.
Rattlesnake snake bites usually begin to swell within 10 minutes and sometimes are painful. Other symptoms include skin blisters and discoloration, weakness, sweating, nausea, faintness, dizziness, bruising, and tender lymph nodes.Severe poisoning can lead to, muscle contractions, increased heart rate, rapid breathing, large drops in body temperature and blood pressure, vomiting ofblood, and coma.
Coral snake bites are painful but may be hard to see. After some time has passed, the victim begins to experience the effects of the venom, which includetingling at the wound site, weakness, nausea, vomiting, excessive salivation,and irrational behavior. Nerves in the head can become paralyzed for 6-14 days, causing double vision, difficulty swallowing and speaking, respiratory failure, and other problems. Six to eight weeks may be needed before the victimregains muscular strength.
Jellyfish venom is delivered by barbs located on the creature's tentacles. They penetrate the skin of people who brush up against them. Red lesions that are instantly painful and itchy usually result. The pain can continue up to 48hours. Severe cases may lead to skin death, muscle spasms and cramps, vomiting, nausea, diarrhea, headaches, and excessive sweating.
Stingrays deliver their venom through tail spines. They may cause puncture wounds, and pieces of spine can become embedded in the wound. Stingray venom produces immediate, excruciating pain that lasts several hours. Sometimes the victim suffers a severe reaction, including vomiting, diarrhea, hemorrhage (bleeding), a drop in blood pressure, and cardiac arrhythmia (disordered heart action).
Gathering information on the circumstances of the bite is part of bite treatment. This information includes when the bite occurred (the chances of infection increase dramatically, if the wound has been left untreated more than eight hours), the patient's general health, tetanus immunization history, and allergies. Laboratory tests for identifying the microorganisms in bite wounds are ordered only if infection has set in. Testing the victim's blood for hepatitis B and other diseases is always necessary after a human bite. Ideally, thebiter should be tested as well.
Minor dog bites can be treated at home by washing the wound with soap and water and applying apply antibiotic ointment and a sterile bandage to the wound.Serious dog bites must be looked at by a medical professional promptly. Diabetics, AIDS patients, cancer patients, and people who have not had a tetanusshot in five years, should seek medical treatment no matter how minor the bite appears.
Because of the high risk of infection, people who are bitten by a cat shouldalways see a doctor. Experts advise, that cat-bite wounds should always be left open to prevent infection. Cat-bite patients are also more likely to receive antibiotics as a preventive measure.
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. The patient may also require immunization against hepatitis B and other diseases.
No spider bite should be ignored. The antidote for severe widow spider bitesis a substance called antivenin that contains antibodies to the poison. Doctors exercise caution in using antivenin because it can trigger anaphylactic shock, a potentially deadly allergic reaction, and serum sickness, an inflammatory response that can give rise to joint pain, a fever, rashes, and other unpleasant consequences.
An antivenin for brown spider bites exists as well, but it is not yet available in the United States. The drug dapsone, used to treat leprosy, can sometimes stop the tissue death associated with a brown spider bite.
Most bee and wasp stings can be treated at home. Victims who experience an allergic reaction require immediate medical attention. The danger signs, whichusually begin 10 minutes after the person is stung, include nausea, chest pain, abdominal cramps, diarrhea, and difficulty swallowing or breathing.
Although most snakes are not venomous, any snakebite should be examined at ahospital. For jellyfish stings, vinegar is used to neutralize jellyfish nematocysts still clinging to the skin. Anesthetic ointments, antihistamine creams, and steroid lotions applied to the skin are sometimes beneficial. Stingraywounds should be washed with saltwater and then soaked in very hot water for30-90 minutes to neutralize the venom. Afterwards, the wound should be examined by a doctor to ensure that no pieces of spine remain.