SELECTED STUDIES

Morsology: Tropical Animal Bites

By Prof. Raymond A. Dieter, Jr., Dr. Robert Dieter, Dr. Raymond A. Dieter III and Dr. David Dieter

 

 

Warm and Cold-blooded Animal Bites

Literally every living thing with a mouth may bite some other living thing. Most concerning bites, however, are limited to warm-blooded animals and insects. A review of animal bites includes animals the size of a tiny mouse to the giant elephant. Mammals are typically warm-blooded with four-feet and breathing air. Their teeth are in sockets and the young are nourished by milk. They have a relatively thick skin and may develop hair, nails, claws, hooves, horns, and scales. This group of animals may include a number of classifications including animals from the various continents, domestic animals, carnivores, and tree or forest animals, as well as the scavenger or dog-like mammal, the marine, and the flying mammals.

Other animals that bite may include the cold-blooded animals, such as reptiles and snakes. The type of dentition that these animals carry affects the type of bite and the amount of damage and injury created by the bite. Some teeth may be blade-like, acting like scissors; others may be wide, flat, and crushing in nature.

Animals bites are common throughout the world, whether it be in the tropics or the arctic region. Most animal bites don't lead to any serious injury and most animal bites occur because of pets and domesticated animals. Wild animal bites less commonly injure the human, but more commonly may inflict serious injury.

Considering the climatic conditions, one will have different bites according to different locations and different types of animals. In the hot, humid countries, one will see a different type of wild animal as compared to the cold or mountainous, high altitude areas. Concomitant injuries from additional flea or insect born disease may occur more commonly in the warm climates. As example, participants in the Desert Storm operations of a decade ago had a large nuber of Klebsiella, E.coli, Bordetella, and Clostridia infections as well as staphylococci all of which were carried by the working military dogs.

Travelers and Consequences

The individual traveling around the world should be aware of potential bites and their consequences, particularly when that individual will be in the outdoors or remote areas. Volunteers, such as missionaries and Peace Corps individuals, may be placing themselves at greater risk. The animals causing their bites may also carry ticks, fleas, and other vectors for bacterial and viral diseases, such as rabies and malaria. Immunocompromised individuals, who are particularly at risk, should consider vaccines, drugs, or other drugs to bolster their immunity to secondary infections. In addition, these individuals should be aware of the potential risk of HIV, rabies, and hepatitis transmission. With increased pressure on the wild animal, more contact takes place between the human and the animal population. Thus an increased number of injures may occur. Pre-travel education, as well as immunization programs, should be considered. Prophylactic rabies, tetanus toxoide, and antibiotic treatment must all be kept in mind.

The consequences of most bites are usually minimal with no major damage inflicted. However, in some areas, particularly areas where rabies vaccination of domestic animals is lacking, a high incidence of rabies may occur. The type of animal and the specific type of dental structure is a great determinant of the type of injury and their secondary effects. A domestic horse or cow will have a different bite than a flying bat, mouse, or a lion. Reporting of these injuries and thus the follow-up in many areas is lacking. Wide flat teeth will cause a crushing or flattening type of injury, whereas sharp, pointed teeth may create more punctures. Shorter teeth may cause scratches, lacerations, or abrasions. The younger child will have injury to the lower extremities, and the hands as well as the face. Larger animals will bite higher on the torso and upper extremities or head. Depending again on the type of injury, the potential of serious cellulitis, osteomyelitis, abscess formation, infectious disease, and bacteremia is ever present. Culture of the wounds and appropriate antibiotic therapy for the multitude of potential bacterial or other infectious organisms, may be beneficial.

Specific Animal Bites

Domestic Animals

There are approximately 52 million dogs and 54 million cats in the United States alone. Each year it is estimated that 4.7 million Americans are bitten by dogs. It is further estimated that 50% of Americans will be bitten during their lifetime. Half of the dog bites occur in children under the age of 12, with 15-20% of them becoming infected. Reading the newspapers from around the world, whether it is Romania, Somalia, the United States, or Tanzania, there are outbreaks of dog bites and severe infection or injuries as a result. On occasion, death results, and these are particularly reported in children. Cellulitis and amputations also occur and a large number of individuals may require antibiotic injections because of the dog bites. Hand, fist, face, arm, scrotum, buttocks may all be bitten. Fractured ribs and collapsed lungs may be the consequences.

Cats are the second most common cause of human bites and their bites are deep due to their sharp pointed teeth. Approxiametly 1.5 million cat bites are reported each year in the US. Reporting systems however are incomplete and poorly integrated. Microorganisms, particularly pasteurella multocida, are carried even by healthy members of the cat family. In addition, cat scratch fever can follow a bite and may be caused by the gram-negative rod Bartonella. Tularemia, particularly from stray cats, may be a consideration. Thus avoiding the wild or free running cat or dog is of importance. Other domestic animals including the rabbit, ferret, gerbil, may bite on occasion, but this is uncommon and their bites are usually not severe. Wild animals converted to the home life may be more devastating, particularly when the raccoon, skunk, coyote or wolf, attack an unsuspecting human.

Zoo Animals

Zoo animals, as well as laboratory and private animal collections, are also a cause of major injury. These animals may carry disease including, rabies, even though they are in captivity or petting zoos. The animals should have appropriate quarters and one should take care in the handling of these animals. Captive animals, including lions, tigers, leopards, may all cause mauling and injuries. Pet monkeys frequently bite during wrestling periods.

Working Animals

There are a large number of animals used on farms or other areas, which ordinarily are docile and create little concern. These animals may turn to the attack mode in unusual circumstances creating serious injury, including osteomyelitis, chronic purulent wound discharges, and severe crush or penetrating injuries. Of note, the camel "the ship of the desert" has a long mandibular jaw with incissors and canine teeth, which may grip and crush, creating a fertile field for infections. The elephant usually docile in its surroundings have heavy tusks and enourmous molars. They may run at great speed and a rogue bull may attack without notice. Their usual injury is caused by trampling or stamping. They may carry the herpes virus as well as rabies. Horses again usually don't bite, but when they do, injury about the face and head as well as traumatic amputations of the upper extremity have all been noted. A number of bacterial organisms are carried by these animals including actinobacillus, pasteurella, streptococcal organisms, and clostridia tetanus organism. Food animals such as cow, donkey, or sheep, usually don't bite, but on occasion they may, and when such bites occur, the possibility of rabies or other diseases transmitted by the mosquito or the bat must be considered.

Large Cats

The lion, the king of the jungle, is mentioned in many books and there are many stories of their incredible strength and ability to carry large weights, such as a cow in their mouth. The man-eating tigers of Kenya or of Tanganyika have killed as many as 380 people. These are uncommon in modern times but tiger injuries or deaths still are reported in the India area. Both they and the lion may create severe injuries and prophylactic therapy for these injuries as well as wide debridement are important. These animals also carry pasteurella multocida organsim. The leopard and the cougar continue to be of concern. The cougar, which is increasing in numbers in the United States, may track, stalk, and attack the human.

Bear injuries are uncommon in the tropics and more common in the northern sub arctic areas. Avulsion injuries as well as death may occur, but the total number of these injuries is relatively low. Treating the patient for shock and cleansing of the wounds is of importance.

Scavengers and Wild Dogs

The wolf is a powerful animal and may kill as many as 40 people in India in a given period. They carry rabies, as do the wild dogs. The hyena has strong powerful jaws and thus may create crush injuries and the secondary complications of such.

Reptiles

One should not diminish or ignore reptile bites. Depending on the areas of the world where one lives, the reptile considerations may be much greater than in other areas. The turtle in some areas may become large and may have a potential capability of creating injury requiring an orthopedic approach. The lizards vary in size from the small to the very large. The bearded lizard of Mexico and the hila monster, are the only lizards known to evenomate their pray. The hila monster may grow up to 20 inches and the Mexican lizard may reach 3 feet. Their bites are uncommon and rarely lethal, but significant swelling may occur and the lizard may hold on for some time as compared to some animals may bite and withdraw quickly. The Kamoto dragon (the largest known lizard) which may weigh 350 pounds, rarely attacks a human. However, the crocodile and alligator both should be approached carefully as their movements are fast over land as well as over the sea. Alligators can gallop over short distances and have a narrow snout. In Tanzania, 51 deaths were recorded in one four-year period, 1990-1994, because of crocodiles. Again prevention is the key. Their bites all may carry multiple bacterial organisms and drowning is quite frequent in these situations.

The snake population is of particular concern. There are five venomous snake families and many of these are in the Middle East and Africa. However, they do occur in multiple other locations around the world. The animals may be particularly concerning to the small child and again multiple bacterial injuries may develop because of these attacks. The coral snake has extremely toxic venom and fortunately they seldom envenonmize the human. Treatment of these bites may be expected. Antiserum and avoidance of the snake are key to the recovery and safety of the individual.

Other Animals

Flying mammals, particularly the bat, may carry multiple diseases including the Venezuela equine encephalitis, rabies, and the fungus histoplasmosis. The vampire bats also may cause open lesions containing the screwworm and the human as well as the non-human should protect against these transmissible disease. Rodents, mice, and rats are uncommonly an etiology of a problem. However multiple diseases may pass through these bites including leptospirosis, sporotrichosis, and rat bite fever. In small children or infants, blood loss and severe injury from multiple rat attacks are reported. Elimination of their food source will reduce this incident immensely. The Australian mammals, kangaroo, and the wallabies, ordinarily are not biters. The mountain animals, including the llamas and alpacas, have a tendency to spit and they have large and pointed teeth, which cause immense concern among the therapist.

Treatment

Treatment of bitten individuals requires early and prompt examination and notification. One should record the data, the facts about the injury, and use a standardized report. Unfortunately, there are no good standardized reporting system nor reporting centers. Again avoidence is the best of these methods. Once there is a bite, one should identify the animal and if possible, capture, or in one-way or the other eliminate their moving out of the area. When there is any concern, immunization for viral diseases such as hepatitis and rabies or pre-exposure human diploid cell vaccine should be considered. The acutely traumatized individual must be stabilized prior to transportation. When they are relatively stable, urgent transportation is best in a major injury. The lesser injury should be evaluated when any change develops. Programs of exposure consideration for tourists have been developed and should be followed. the medical history will reveal whether the patient has been on anticoagulants, had previous such attacks, or has an allergies. Antibiotic therapy after culture of the wounds should be initiated as well as laboratory and x-ray studies where necessary. Local wound management along with debridement is important. Undo pressure on the incision will create additional difficulties in developing a healing program. When the lesions are deep or concerning as to function of potential bleeding, then surgical intervention with full operating capabilities should be available. Stabilization of fractures, along with debridement of wounds should be considered. Hand injuries should not be closed to avoid the lymphangitis that may develop. Photographs of the injuries will allow one the opportunity for better follow-up examination. Pre-exposure prophylaxis, for certain diseases as well as the administration of rest, ice, and compresses, may be beneficial. Leaving the wound open at this point should be standard consideration. Adequate nutrition assists the healing process. Morbidity may be great. Mortality is usually low, but injuries that are severe and disfiguring certainly occur as well as death on occasion. Death from large wild animals, particularly those in Africa, again are uncommon, but certainly may and do occur. Again, avoidance is the key to this program.

Human Bites

One of the more feared type of bites is the human bite. Many of these are a result of fighting or the clinched fist syndrome. Injury to the knuckle or to the hand may be deeper than one suspects and it may lead to abscess formation, to cellulitis, and to osteomyelitis. The organisms carried may be many and the treating of the infectious process may require open surgery. Treatments should begin early, rather than later in the course of the disease process. A number of human bites in addition to the accidental ones may include human bites to the nose, the breasts or to the genital organs. Amputation of the tip of the nose in newly-weds and as a penalty for adulterers is well recognized in parts of the world. Transmission of viral diseases from human bites including hepatitis and HIV must remain a potential. Treatment of these injuries includes early examination, antibiotics considerations, soaking, and immobilization.

Prof. Raymond A. Dieter, Jr. MD is the President of the Northern Illinois Surgicenter (USA) and of the International College of Surgeons. He can be reached at 475 East Diehl Road, Naperville, Illinois 60563, USA.


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