Introduction
Background
Human bite wounds have a notorious reputation, which is mostly based on one injury, the closed-fist injury. Human bites in other areas pose no greater risk than animal bites. Three general types of injuries can lead to complications: (1) closed-fist injury, (2) chomping injury to the finger, and (3) puncture-type wounds about the head caused by clashing with a tooth. Otherwise, the general principles of contaminated wound management apply to human bite wounds.
For more information, see Medscape's Wound Management Resource Center.
Pathophysiology
In a closed-fist injury, forces sufficient to break the skin from striking an opponent's tooth often inoculate the extensor tendon and its sheath. As the hand is flexed at the time of impact, the bacterial load is transferred caudally when the hand is opened and the tendon slides back to its relaxed state. Resulting contamination cannot be removed readily through normal cleansing and irrigation.
When a finger is bitten, such as in a chomping-type injury, tendons and their overlying sheaths are in close proximity to the skin. The wound may appear to be a minor abrasion-type injury, but careful inspection is required to rule out deep injury.
When a tooth strikes the head, even a deep puncture wound may appear innocuous. Deep, subgaleal, bacterial contamination is possible. This is especially true in young children who have relatively thin soft scalp and forehead tissue.
Frequency
United States
Exact incidence of human bite wounds is unknown, and many cases do not come to medical attention. Institutionalized patients with poor impulse control create a high-risk environment for human bite wounds. Lesch-Nyhan syndrome is an uncommon disorder that includes self-mutilation through biting.
International
In a 4-year retrospective review in the United Kingdom, 421 (13%) human bites were identified out of 3136 case notes. The majority of those bitten were young males, with 44% of the males aged 16-25 years. The male-to-female ratio was 3:1.1
Mortality/Morbidity
- The primary concern with human bites of the hand is infection, which can be severe because of spread along tendon sheaths and deep into the hand. Surgical incision and drainage may be needed. Resultant scarring and tissue damage may compromise normal function of the hand.
- Infection also is the major complication of bites in other areas of the body. Most can be treated adequately; however, infections of poorly vascularized structures, such as ear cartilage, may be difficult to treat.
- Other serious infectious complications such as osteomyelitis of the skull vault, necrotizing fasciitis, and septic arthritis have been associated with human bites. Transmission of human immunodeficiency virus (HIV) has been reported as a result of a human bite wound.
Sex
- Males generally are at higher risk than females for bite wounds due to their typically more aggressive nature. Closed-fist injuries are encountered almost exclusively in young males.
Age
- Closed-fist injuries occur most often in adolescents and adults younger than 40 years.
- Toddlers frequently bite one another, but injuries usually are superficial and low risk.
- Penetrating tooth injuries of the scalp and forehead pose a higher risk to young patients than to older patients.
Clinical
History
- Consider all injuries dorsal to the metacarpophalangeal (MCP) joint bite wounds until proven otherwise. Explanations offered for such wounds often are misleading, thus extreme caution is necessary. While a careful explanation of the need for an accurate history may elicit the truth from the patient, experienced emergency physicians often treat such injuries as bites regardless of the history.
- Most bite wound infections are present at the initial ED visit. With closed-fist injuries, the initial injury often appears minor to the patient, thus no care is sought until infection develops. If a child receives a small laceration to the scalp or forehead during unwitnessed horseplay, carefully ascertain whether a tooth caused the wound to minimize complications.
- Other aspects of a patient's history that may influence care include tetanus immunization status, time delay from injury to presentation, disability encountered, and the presence of underlying immunosuppressive disease.
Physical
- Physicians must be wary of any laceration overlying the MCP joint. Additionally, carefully assess bite wounds of the fingers for deeper penetration into the tendon apparatus. Extending the wound may be necessary to fully evaluate the underlying structures and the extent of injury.
- The following points should be noted for specific bite wounds:
- MCP wounds (closed-fist injury) - Integrity of the extensor tendons, signs of infection, crepitation, loss of knuckle height
- Chomping injuries of the finger - Integrity of the extensor and flexor tendons, evidence of infection including flexor tenosynovitis
- Ear bites - Loss of tissue, violation of cartilage
- Other bites - Tissue loss, depth of penetration
Causes
- As with most intentional injuries, human bites often are the result of an incident involving alcohol.
- Domestic violence may be a factor.
- Child abuse may be associated with bite wounds from adults.
More on Bites, Human |
 Overview: Bites, Human |
| Differential Diagnoses & Workup: Bites, Human |
| Treatment & Medication: Bites, Human |
| Follow-up: Bites, Human |
| References |
| Further Reading |
| Next Page » |
References
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Broder J, Jerrard D, Olshaker J, Witting M. Low risk of infection in selected human bites treated without antibiotics. Am J Emerg Med. Jan 2004;22(1):10-3. [Medline].
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Smith DK, Grohskopf LA, Black RJ, et al. Antiretroviral postexposure prophylaxis after sexual, injection-drug use, or other nonoccupational exposure to HIV in the United States: recommendations from the U.S. Department of Health and Human Services. MMWR Recomm Rep. Jan 21 2005;54(RR-2):1-20. [Medline].
Talan DA, Abrahamian FM, Moran GJ, et al. Clinical presentation and bacteriologic analysis of infected human bites in patients presenting to emergency departments. Clin Infect Dis. Dec 1 2003;37(11):1481-9. [Medline].
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Kelly IP, Cunney RJ, Smyth EG, Colville J. The management of human bite injuries of the hand. Injury. Sep 1996;27(7):481-4. [Medline].
Lindsey D, Christopher M, Hollenbach J, et al. Natural course of the human bite wound: incidence of infection and complications in 434 bites and 803 lacerations in the same group of patients. J Trauma. Jan 1987;27(1):45-8. [Medline].
Miura I, Ohshima A, Takahashi N, et al. A new non-random chromosomal translocation t(3;6)(q27;p21.3) associated with BCL6 rearrangement in two patients with non-Hodgkin's lymphoma. Int J Hematol. Oct 1996;64(3-4):249-56. [Medline].
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Further Reading
Clinical guidelines
Management of human bite wounds. University of Texas, School of Nursing, Family Nurse Practitioner Program. Management of human bite wounds. Austin (TX): University of Texas, School of Nursing; 2007 May. 22 p.
Antiretroviral postexposure prophylaxis after sexual, injection-drug use, or other nonoccupational exposure to HIV in the United States: recommendations from the U.S. Department of Health and Human Services. Smith DK, Grohskopf LA, Black RJ, Auerbach JD, Veronese F, Struble KA, Cheever L, Johnson M, Paxton LA, Onorato IM, Greenberg AE. Antiretroviral postexposure prophylaxis after sexual, injection-drug use, or other nonoccupational exposure to HIV in the United States: recommendations from the U.S. Department of Health and Human Services. MMWR Recomm Rep 2005 Jan 21;54(RR-2):1-26. [126 references] PubMed
Practice guidelines for the diagnosis and management of skin and soft-tissue infections. Stevens DL, Bisno AL, Chambers HF, Everett ED, Dellinger P, Goldstein EJ, Gorbach SL, Hirschmann JV, Kaplan EL, Montoya JG, Wade JC. Practice guidelines for the diagnosis and management of skin and soft-tissue infections. Clin Infect Dis 2005 Nov 15;41(10):1373-406. [236 references] PubMed
Keywords
human bites, human bite wound, closed-fist injury, chomping injury, puncture-type wound, infected human bite wounds, bite wounds, bite injury
