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.

Skunks

In addition to biting a person and inoculating him with rabies virus, a skunk can spray secretions from its anal sacs. The main component of skunk musk is butyl mercaptan, which carries a horrible odor and causes skin irritation, eye redness and temporary blindness, and occasional seizures or loss of consciousness. The odor can be neutralized by strong oxidizing agents, such as household bleach diluted 1:5 with water. This solution can then be washed away with tincture of green soap, followed by a more dilute bleach rinse. An alternative mixture is 1 quart of 3% hydrogen peroxide, ¼ cup of baking soda, and 1 tsp of liquid laundry detergent. A surprisingly effective product to neutralize skunk spray odor is Summer’s Eve douche (C.B. Fleet Company, Inc.). To “deskunk” an animal, such as a dog, the method is to apply it directly to the fur and work it into the deeper layers by hand. It may take many bottles to accomplish the task. For the animal’s face, use a washcloth with the solution to apply the product. Tomato juice has been recommended, but may not be very effective, to deodorize hair, which may need to be bleached or cut short. Two other methods that have been recommended (but which I have not personally attempted) are:

Bubonic Plague

Cases of bubonic plague are still reported in the United States. The disease is transmitted by the bites of fleas that have acquired the plague bacillus, Yersinia pestis, from infected squirrels, rats, prairie dogs, chipmunks, marmots, rabbits, and mice. Rarely, the disease can be contracted from direct contact with infected pets, particularly cats. It can also be contracted from skinning an infected wild animal, such as a coyote or bobcat.

The incubation period for bubonic plague is 2 to 6 days after exposure. At first, the victim complains of high fever, chills, severe fatigue, abdominal pain, vomiting, diarrhea, muscle aches, and headache. At the same time, he develops extremely enlarged and tender lymph nodes associated with the entry point for the disease, such as in the groin if an insect bite has occurred on the leg. Thereafter, as the bacteria overwhelm the victim, he may collapse and develop a skin rash with large dark patches of hemorrhage (“Black Death”). If pneumonia develops, the victim coughs bloody sputum.

Treatment should be initiated promptly, and requires intramuscular or intravenous antibiotics. If you are isolated away from a hospital, start the victim on tetracycline 1 g for the first dose, then 50 mg/kg (2.2 lb) of body weight in six divided doses every 4 hours for the first day, then 30 mg/kg of body weight in four divided doses every 6 hours for 14 days. This is extremely suboptimal therapy; the victim needs to get to a hospital as soon as possible. The best available drug is streptomycin, which is administered by intramuscular injection.

The disease is contagious. All adults in direct face-to-face contact with a victim suffering from plague pneumonia (cough productive of sputum) should take tetracycline 500 mg four times a day, or trimethoprim-sulfamethoxazole one double-strength tablet twice a day, for 8 days. Children should take a pediatric dose of trimethoprim-sulfamethoxazole for 8 days. All contact people should have their temperature measured twice a day. If anyone develops a fever greater than 100°F (37.7°C), he should begin taking an antibiotic and be taken immediately to a physician.

With regard to prevention, pay attention to local public health warnings and do not travel with pets in areas of plague infestation. Take care to spray or dust your canine and feline companions with flea repellent regularly (after each time they get wet) when traveling in wooded areas. Do not allow children to handle small dead animals.

Preexposure immunization against plague is available (see page 455). If you have not been immunized against plague and will be actively exposed to plague-infected animals, ingest tetracycline 500 mg four times a day during the period of exposure.

Anthrax

Anthrax is a communicable disease caused by Bacillus anthracis transmitted by spores via inhalation, ingestion (contaminated meat), or inoculation into the skin. The spores can persist in the environment for years, and are typically present in infected animals or contaminated animal products. Anthrax is not transmitted from person to person. After exposure to the spores, the incubation period is typically 1 to 5 days, although it can be as long as 40 days. With inhalation anthrax, the victim initially has a nonspecific flu-like illness (fever, fatigue, muscle pains, dry cough, and chest or abdominal pain) followed by severe respiratory distress and overwhelming infection that leads to shock and death. With cutaneous anthrax, the first lesion is usually a painless red raised area on the head, neck, or limb, usually at the site of a small cut or scrape through which the spore enters. In a day or two, a clear blister(s) forms, surrounded by swelling. The blister ruptures, and then turns into an ulcer covered by a black crust in a few days. This disappears in a few weeks. With gastrointestinal anthrax, the victim suffers abdominal pain and swelling, nausea, vomiting, and bloody diarrhea 2 to 5 days after eating the undercooked spore-containing meat. He may also suffer from dizziness, fatigue, muscle aching, and fever. Anthrax may rarely cause primary infection of the lining of the brain, and cause a clinical presentation similar to meningitis (see page 174).

Any adult known to be exposed to anthrax or who is believed to be suffering from anthrax should be administered ciprofloxacin 500 or 750 mg by mouth or doxycycline 100 mg by mouth twice a day until it is determined if the anthrax is susceptible to penicillin or amoxicillin, at which time the antibiotic therapy can be altered. Although ciprofloxacin and doxycycline are usually avoided in children because of potential damage to teeth or bone growth, in the setting of anthrax exposure, the benefits probably outweigh the risks. The pediatric doses are ciprofloxacin 10 to 15 mg/kg of body weight or doxycycline 4.4 mg/kg of body weight daily in two divided doses. Anthrax vaccine can be administered in three doses—on the day of exposure, day 14, and day 28—so antibiotic therapy should be continued for 28 days if the vaccine is administered, and for 60 days if the vaccine is not available.

Hantavirus Pulmonary (Lung) Syndrome

Hantaviruses (such as the sin nombre virus) cause a syndrome characterized by a combination of fever, lung failure, kidney failure, shock, and bleeding. The viruses are spread in the excreta of rodents; in the United States, hantavirus pulmonary syndrome (HPS) has been linked to the deer mouse (Peromyscus maniculatus) and white-footed mouse (P. leucopus), as well as to the cotton rat (Sigmodon hispidus) and rice rat (Oryzomys palustris). The animals shed the virus in saliva, urine, and feces. Aerosols are the most likely route of transmission from rodents to humans. Insect bites have not yet been implicated in transmission.

HPS has now been reported in most states west of the Mississippi River, as well as in a few eastern states. In Louisiana and Florida, two hantavirus species, bayou virus and Black Creek virus, have been identified. A person infected by the virus has an incubation period of 1 to 5 weeks after exposure, and then suffers from fever, muscle aches, headache, cough, dizziness, abdominal pain, nausea and vomiting, and diarrhea for a few days; this is followed by difficulty breathing, mottled skin on the limbs, shock, and, sometimes, bleeding. Up to 75% of victims may die.

Most victims have had an interaction with rodents, such as when cleaning a barn or capturing the animals. Unfortunately, there is not yet any specific therapy beyond supportive care, although the antiviral agent ribavirin may prove useful.

To avoid unnecessary exposure to hantavirus, it is recommended that wilderness enthusiasts observe the following precautions: keep food and water covered and stored in rodent-proof containers; dispose of food clutter; spray dead rodents, nests, and droppings with disinfectant before handling (wear gloves); clean and disinfect cabins and other shelters thoroughly before using; don’t make camp near rodent sites; don’t sleep on bare ground; burn or bury garbage promptly; and use only bottled or disinfected water for campsite purposes.