A 4-year review of human bite injuries presenting to emergency medicineand proposed evidence-based guidelines

Mark Harrison *

Department of Emergency Medicine, James Cook University Hospital, Middlesbrough, United Kingdom

Injury, Int. J. Care Injured 40 (2009) 826–830

A R T I C L E I N F O

Article history:

Accepted 10 June 2008

Keywords:

Human bite

Guidelines

Treatment

Emergency

Evidence-based medicine

A B S T R A C T

Human bite injuries are a common injury, roughly accounting for around 0.1% of attendances to

Emergency Medicine departments. Morbidities associated with such injuries are legion. Of paramount

importance is the potential for infection of the wound site, both bacterial and viral.

A retrospective 4-year review of 3136 case notes was conducted, identifying 421 human bites. This

amounts to one every 3 days! The majority of those bitten were young males (male:female ratio = 3:1;

44% comprising the age group 16–25 years).

The management of these wounds was found to be poor. 17% of patients did not receive any antibiotic

cover; 21% of patients either did not have tetanus prophylaxis administered when required or had a

tetanus booster when they were already covered; 34% of patients either did not receive a hepatitis B

booster when one was required or received one when they were already covered.

This lack of effective documentation, along with errors in addressing prophylaxis of the infective

agents, may have profound medico-legal consequences.

The author believes that the findings will be reproduced in other centres and in view of the

inadequacies highlighted by this work, it is necessary to introduce an evidence-based protocol for the

comprehensive management of the human bite. Using United Kingdom Department of Health evidence-

based guidelines, the author proposes such a pathway.

� 2008 Elsevier Ltd. All rights reserved.

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Introduction

Human bite injuries are overall responsible for around 0.1% ofattendances to Emergency Medicine departments (EMDs).4

Despite the seeming low prevalence in the literature, thesignificant morbidity associated with these injuries, as well asthe obvious aesthetic implications, demand careful treatment andapplication of well-documented management strategies.

The socio-economic status and well-publicised increase indrinking culture in Great Britain was seen anecdotally by theauthor to be contributing to an increased prevalence in thispopulation attending EMD with human bite injury compared toother centres.

Morbidities associated with such injuries are legion. Ofparamount importance is the potential for infection of the woundsite, made obvious by the bacterial load found in saliva.5,21

Organisms are found to be isolated from over 50% of human bite

* Correspondence address: ST3 in Emergency Medicine, 38 Rokeby Terrace,

Heaton, Newcastle NE6 5ST, United Kingdom. Tel.: +44 1912651593;

fax: +44 1642854251.

E-mail address: DrMarkHarrison@doctors.org.uk.

0020–1383/$ – see front matter � 2008 Elsevier Ltd. All rights reserved.

doi:10.1016/j.injury.2008.06.044

injuries with regard to bacteria.21 Other studies for viraltransmission have yielded evidence for transmission of hepatitisB and C, tetanus, herpes simplex and HIV.2,7,8,12,17 Furthermore, theimpact of soft tissue loss may be devastating.

This study represents a review of bite injuries and theirmanagement in a population presenting to the EMD of a level onetrauma centre in England.

Methods

A retrospective 4-year review of case notes was conductedbetween January 2003 and December 2006 inclusive. Inclusioncriteria, for identification purposes, were all patients coded as ‘17—Bites or Stings’. Exclusion criteria were stings, self-inflictedwounds and non-human bites.

Of the 3136 notes identified, 2396 were bites, of which 421were human bites (see Table 1).

The following details were recorded and analysed:

� Patient demographics: age, sex, smoker, alcohol and drugconsumption, sports injury, alleged assault, known assailants,date and time of incident.

Table 1Species of assailant.

Animal causing the bite Number of bites

Dog 1473

Human 421

Insect 281

Cat 68

Hamster/guinea pig 40

Unknown 37

Rodent 22

Other 18

Horse 11

Rabbit 10

Bird 8

Snake 7Fig. 2. Time of presentation.

Table 2Time to presentation.

Time to presentation (h) Number (%)

<24 377 (89)

24–48 25 (6)

>48 19 (5)

M. Harrison / Injury, Int. J. Care Injured 40 (2009) 826–830 827

� Injury demographics: site, nature of wound, type of injury andtime to presentation.� Treatment details: wound management, viral transmission

assessment, referred or admitted, and follow-up.

Results

Demographics

As stated above, a total of 421 patients were treated for humanbite injury between 1 January 2003 and 31 December 2006inclusive. 100% of these notes were analysed. 75% of those bittenwere male (n = 314) with 44% overall belonging to the age group16–25 years (range 2–70 years) (see Fig. 1).

Interestingly only 34% (n = 147) stated that they were thevictim of an alleged assault (7% from a known assailant), and only 2patients complained of having sustained the injuries playingsports.

Alcohol was a documented factor in only 12% of cases, andrecreational drug use in only 6%. A patients smoking habits wereonly documented in 9% of cases, of which 78% were non-smokers.

There was no statistically significant trend in presentation withregards to month of presentation. 52% of patients attended duringthe weekend (Friday 1700 h–Monday 0600 h).

Patients presented in equal numbers over the course of the daywith an expected lull between 0400 h and 0900 h (see Fig. 2).

Time to presentation is shown in the table (see Table 2).Of the 421 patients, there were a total of 478 distinct human

bite injuries, thus several patients received more than one injury atthe same time. Location of the bite was analysed and it was foundthat bites to the extremities were most common (Hand and Fingers25%, Ear 15%) (see Fig. 3). 168 (35%) injuries were to the face, with17 of these reporting some degree of tissue loss. Only 11% ofinjuries were ‘fight bites’ of the fingers.

Fig. 1. Age of th

Treatment details

Only 18% of patients presenting with a bite were referred forfurther specialist review. Of those managed in the EMD 10% wereprimarily closed and the remainder undergoing conservativemanagement. Only 50% patients had any documented evidence of awound toilet.

17% of patients did not receive any antibiotic cover.29% of patients (n = 94) received tetanus prophylaxis in our

department. A total of 20% of patients did not have their tetanusstatus documented at all. More worryingly, however, is that 21% ofpatients (n = 83) either did not have tetanus prophylaxis adminis-tered when required or had a tetanus booster when they werealready covered.

Of all the patients, 60% received hepatitis B prophylaxis.Surprisingly therefore 67% of patients had no record of hepatitisstatus documented in their notes. Again, worryingly 34% ofpatients either did not receive a booster when one was required orreceived one when they were already covered.

Only 34 patients (10% of those discharged from EMD) under-went any sort of follow-up.

Discussion

The human bite is a leisure time injury of the young single male.Our results show a male:female ratio of 3:1. Even this however is

ose bitten.

Fig. 3. Location of bite.

M. Harrison / Injury, Int. J. Care Injured 40 (2009) 826–830828

much less than other rates recently reported in the literature,stating up to a ratio of 12:1.10 The injury is not an uncommon one,with an incidence of 1 case roughly every 3 days.

Despite the presumption that alcohol may fuel the incidence ofthe human bite injury as stated in the literature recently,6,10,21 ourstudy revealed only a 12% association. This may well have been,however, because the question was not asked, rather than thepatient being alcohol free. Perhaps this is due to the time ofpresentation. As stated above our patients presented throughoutthe 24 h period, so perhaps ‘slept-it-off’ before presenting in thedaytime hours.

Human bite injuries are not an injury of recent times—in 1936Lowry reported 122 cases of human bites some 8% of which werefacial wounds.14 Subsequently, Boland in 1941 reported 60 cases,40% of which were of the head and neck.3 These early studiesestablished the anatomical basis for differing infection ratesbetween facial and limb injuries, with those wounds around thehand having higher rates of infection. Our injury pattern differsfrom that in the recent literature, mainly because of thecomparative uniqueness of our study. Other published reportsare mainly from a referral centre of some description, whereas oursencompasses the whole range of injuries at the initial presentation.This accounts for our low percentage of face wound for example(35% compared with around 80%6,10).

There are numerous reports in the literature regarding thenecessity for prescription of antibiotics to individuals sustaininghuman bite wounds.19,22 This is secondary to a reported infectionrate of about 20%.10,19 This rate is higher than expected due to theconsiderable bacterial load of saliva, containing over900 � 106 organisms/ml.10 A cochrane review reports a statisticallysignificant reduction in the rate of infection following prophylacticantibiotics.16 Our study demonstrates a large number of patients(73) did not receive any form of antibiotic cover. Unfortunately dueto our cases being from an EMD presentation, it was not possible toascertain the infection rate in the differing groups.

Tetanus transmission

Although only two documented case reports exist in themedical literature, the risk of tetanus transmission in anycontaminated wound is clear.1,17 This study reveals a markeddisparity between the documentation and administration oftetanus prophylaxis in these patients. Overall documentation oftetanus status was poor and it was seen that some patients needingprophylaxis were not covered and in other cases, patients whowere documented as having adequate cover were given unneces-sary further boosters. All patients receiving tetanus prophylaxiswere administered sole toxoid vaccination as opposed to in

combination with immunoglobulin. This addressing of tetanusstatus in a contaminated wound is a basic surgical principle, butone that seems to be being missed on an all-too frequent basis.

Viral transmission

With the advent of HIV and hepatitis B as complications of skinbreaching injury, the literature was also searched for documentedevidence regarding transmission of the viruses by bite injury. Thereare five reported cases of seroconversion to HIV-1 following ahuman bite.2,11,18,23,24 Despite the low numbers reported, the riskof transmission is still apparent and must be addressed on anindividual case basis. Exposure to the virus in saliva alone is notconsidered a risk factor, unless there is HIV infected blood mixedwith this saliva. Even then there has to be a skin break on the victimfor this to be judged a significant exposure.

The risk of hepatitis B transmission is perhaps more widelyknown although the literature is similarly sparse with only fourreferences to transmission of the disease through bitewounds.9,12,15,20 Indeed despite the fact that the World HealthOrganisation (WHO) categorises Great Britain as low prevalence(<2%), recent Department of Health (DoH) guidelines acknowledgethe risk of transmission through a human bite.13 It has been shownthat 75% of hepatitis B patients have detectable antigen in theirsaliva.10 Despite this risk, the documentation of hepatitis B statusand actions taken regarding the threat of this disease has beenfound to be lacking once again.

This lack of effective documentation and errors in addressingprophylaxis of the infective agents of this common injury hasprofound medico-legal consequences.

The author is aware that there are a large number of limitationsto this study. It was a retrospective study relying on the quality ofdocumentation to enable data collection. Clearly a prospectivestudy would allow more accurate documentation and questioningof patients. Not many (8%) of the patients were followed up at all,thus data on healing, completion of immunisations, and woundinfections was not possible to gather.

However, the author believes that the above findings will bereproduced in other centres and in view of the inadequacieshighlighted by this work, it is necessary to introduce an evidence-based protocol for the comprehensive management of the humanbite.

Conclusions

1. There is little argument that prophylactic antibiotics arerecommended for all human bite wounds given the risk ofinfection.19

Table 3DoH tetanus guidelines13.

Immunisation

Status

Fully immunised Primary immunisation

complete, boosters

incomplete but up to date

Primary immunisation

incomplete or boosters

not up to date

Not immunised or status

unknown or uncertain

Vaccine None required None required Reinforcing dose of

vaccine and complete

recommended schedule

Immediate dose of vaccine

and complete full five-dose

course

HTIG Only if high risk Only if high risk Yes Yes

Table 4DoH hepatitis B guidelines13.

HBV status of person exposed �1 dose HB vaccine pre-exposure �2 doses HB vaccine

pre-exposure

(anti-HBs not known)

Known responder to

HB vaccine

(anti-HB > 10 mlU/ml)

Known non-responder

to HB vaccine

(anti-HBs < 10 mlU/ml 2-4

months post-immunisation)

Treatment required Accelerated course of HB vaccine One dose of HB

vaccine

Consider booster dose

of HB vaccine

HBIG, consider booster dose

of HB vaccine, 2nd dose of

HBIG at 1 month

M. Harrison / Injury, Int. J. Care Injured 40 (2009) 826–830 829

2. Tetanus: the immunisation programme provides a total of fivedoses of vaccine at the appropriate intervals, and is consideredto give satisfactory long-term protection. However, as a humanbite wound shows a ‘significant degree of devitalised tissue’ or isa ‘puncture-type injury’, it is classified as a tetanus-pronewound. If there is contamination with material likely to containtetanus spores, and/or extensive devitalised tissue then itbecomes a high risk wound. As such the DoH guidleines13 statethat human tetanus immunoglobulin (HTIG) should be given forimmediate protection, irrespective of the tetanus immunisationhistory of the patient. This is a precautionary recommendationsince there is insufficient current evidence to support otheralternatives (see Table 3).

3. Hepatitis B: any individual potentially exposed to hepatitis B-infected blood or saliva should be offered protection,

Fig. 4. Manageme

depending on their prior vaccination status and the status ofthe source.

DoH guidelines13 reveal that there are two possibilities:

� An inactivated vaccine that confers active immunity.� A specific immunoglobulin (HBIG) that provides passive and

temporary immunity while awaiting response to vaccine.

The vaccine is highly effective at preventing infection if givenwithin 48 h after exposure. It is not necessary for individualsknown to have markers of current (HBsAg) or past (anti-HB)infection. However, immunisation should not be delayed whileawaiting any test results. An accelerated schedule should be used,with vaccine given at zero, 1 and 2 months.

nt guidelines.

M. Harrison / Injury, Int. J. Care Injured 40 (2009) 826–830830

The use of HBIG in addition to vaccine is recommended only inhigh-risk situations or in a known non-responder to vaccine. Thisshould be given within 48 h, although should be considered up to aweek after exposure (see Table 4).

Management guideline

Together then, these can be incorporated into an easy-to-followflow chart to encompass the whole treatment regimen for thehuman bite injury (see Fig. 4).

Conflict of interest

None declared.

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