High-Risk Wounds

Wounds at high risk for infection include bites to the hands and feet, and all puncture wounds (see page 258). These should be rinsed copiously and never cinched shut by any method. Anyone who sustains such a wound should be given antibiotics for 4 days (see step 4 on page 409). Cat, human, and primate bites are enormously prone to infection, and require prompt attention by a physician. In a typical human bite, which occurs when a closed fist strikes an opponent’s teeth, the cut extends deeply into a knuckle and inoculates the underlying tendon sheath with saliva and bacteria. As the fist is opened, the wound becomes “closed,” and an infection can develop quickly. If a human bite is incurred in this manner, splint the hand in the position of function (see Figure 39) and administer cefuroxime axetil, ciprofloxacin plus erythromycin, or dicloxacillin plus ampicillin for 7 days.

Cat Scratch Disease

Cat scratch disease is most commonly caused by bacteria of the genus Bartonella. After the victim is scratched by a cat, commonly on the hand, wrist, or forearm, a reddened or purplish sore forms at the scratch site within a few days. The sore may blister and then settle into an ulcer that remains for days to weeks. Along with the sore, the victim typically complains of swollen lymph glands (nodes) directly upstream from the injury. In the case of a scratch on the hand, these would appear behind the elbow and in the armpit. The swollen nodes are often tender and sometimes matted together. On occasion, they may become severely inflamed, soften, and drain through the skin surface. The victim may also complain of fever and fatigue. Although the response to antibiotics is not consistent, the victim may benefit from azithromycin 500 mg by mouth once a day for 5 days, or from a 5-day course of ciprofloxacin or clarithromycin.

Rabies

Rabies virus infection occurs more frequently in wild than in domestic animals. In some foreign countries where immunization of animals is infrequently practiced, the risk is great even in domesticated animals. The virus is carried in saliva and is transmitted by bite or lick (if the skin is broken). It has been transmitted by bats in caves either by aerosolized saliva or undetected bites. Raccoons, dogs, cats, foxes, coyotes, skunks, wolves, bats, woodchucks, and groundhogs are the most common carriers. Rabies has not been reported in bears. Although rabbits, hares, mice, squirrels, chipmunks, rats, guinea pigs, and ferrets may be rabid, they are rarely involved in the transmission of rabies to humans. Domestic animals such as cattle, horses, and sheep become infected in regions where skunk or raccoon rabies is found. In developing countries in Asia, Africa, and South and Central America, dogs are the most common carriers.

Animals with rabies show abnormal behavior. In the “furious” phase, they are hyperactive, may have a fever, are overtly aggressive, and salivate excessively. With “dumb” rabies, they appear tired, lack coordination, and may become paralyzed.

Because of rabies risk, all wild animal bites or scratches, and bites or scratches of unregistered or strangely behaving cats and dogs, should be reported to the appropriate public health authority. If the animal is a pet with otherwise normal behavior, it should be observed for 10 days. If the animal is rabid, it will become very ill or die during that time, and its brain tissue can be analyzed for the presence of rabies. If the animal is a pet with unusual behavior, or a captured high-risk wild animal, it should be killed and examined. If it is a high-risk animal and cannot be captured, it must be presumed to be rabid.

Immediately scrub an animal bite wound or a wound that has been licked by a potentially rabid animal vigorously with soap and water. If benzalkonium chloride 1% (Zephiran); 10% povidone iodine (Betadine) solution (less effective); or, in a pinch, Bactine (benzalkonium 0.13%) antiseptic is available, one of these should be used to irrigate and deeply swab the wound, since they may kill rabies virus.

If rabies is a consideration, the victim should seek the assistance of a physician, who will determine the need for postexposure rabies vaccination (a series of five injections) and injection of antirabies serum (human rabies immune globulin; as much as possible is injected around the bite wound, and the remainder intramuscularly). A person who has been previously immunized against rabies still needs two booster doses of rabies vaccine after high-risk contact with a rabid animal. In countries (Africa, Asia) where rabies is very prevalent in dogs and cats, the vaccination status of the biting animal should be ignored, because the vaccination may not have occurred or may have been ineffective. Begin postexposure vaccination of the human victim and then discontinue after 10 days if the biting animal is observed to remain healthy during that time period.

Preexposure vaccination against rabies should be administered to people at high risk of exposure (animal handlers, cavers, hunters, and trappers in rabies-endemic areas, along with travelers to certain foreign countries). This is given as a series of three intramuscular injections over 28 days, although a newer 1-week schedule for the injections appears to be quite effective. An intradermal regimen can be used for immunization, but this technique may result in lower antibody level.

The incubation period of rabies ranges from 9 days to more than 1 year, but is usually between 2 and 16 weeks. The first symptoms are fatigue, weakness, anxiety, irritability, fever, headache, nausea and vomiting, sore throat, abdominal pain, and loss of appetite. Some victims complain of numbness and tingling where they were initially bitten. After a few days to 2 weeks, the virus shows its devastating effect on the nervous system, with symptoms of increased agitation, hyperactivity, seizures, hallucinations, uncontrollable behavior, and inability to drink (hydrophobia) because of muscle spasms in the throat. This constellation is called “furious rabies.” With “dumb” rabies, a person becomes progressively weak, uncoordinated, and paralyzed. Unfortunately, rabies is virtually always fatal, with the terminal events being one or more of coma, respiratory failure, seizures, abnormal heart rhythms, paralysis, and pneumonia.

To avoid rabies, be certain that all pets and livestock are properly vaccinated, do not feed or handle wild animals, do not feed or touch stray animals, avoid sick or strange-acting animals, keep garbage and food (including feed for animals) covered and away from wild animals, do not keep wild animals as pets, do not touch or pick up dead animals, and do not handle bats.