Inoculation Injuries

• Introduction.
• Legal requirements.
• Reducing inoculation injuries.
• Immunization against blood-borne viruses.
• Risk factors for blood-borne viruses.
• Risks of transmission of blood-borne viruses in the health care setting.
• What to do following an inoculation injury.

Introduction

• The information included in this page:
  • Is an adjunct to B.D.A. Advice Sheet A12 'Infection Control in Dentistry'.
  • Is largely drawn from 'Guidance for Clinical Health Care Workers: Protection against Infection with Blood-borne Viruses' published by the U.K. Health Departments (link).
• Further information and advice has been published recently in the BDJ:
  • 'Management of needlestick injuries in general dental practice'. Smith et al. British Dental Journal 2001; 190: 645-650.
• An Inoculation Injury includes all instances where:
  • A object or substance contaminated by blood or other body fluids (e.g. saliva).
  • Either:
    • Breaches the integrity of the skin or mucosa (e.g. puncture wounds or lacerations), or
    • Comes into contact with the eyes.
• The nature of dentistry places the dental team at risk of inoculation injuries from many sources including:
  • Needles, sharp-edged instruments, broken glassware, or spicules of bone or teeth.
• The major hazard associated with inocualtion injuries is the transmission of Blood-borne Viruses (BBVs), and in particular:
  • Hepatitis B.
  • Hepatitis C.
  • HIV.
• Potentially there may be other BBVs of clinical significance:
  • There have been recent concerns about possible transmission of Hepatitis G (also known as GBV-C) in the dental surgery.
  • The significance of this virus to human health and whether transmission does occur during dental treatment remains unclear.

Legal Requirements

• Dental surgeons have a legal obligation under the Health and Safety at Work Act 1974 to ensure that all their employees are appropriately trained and proficient in the procedures necessary for working safely.
  • There is also a responsibility to protect voluntary workers.
• Employers are required by the Control of Substances Hazardous to Health Regulations 1994 (COSHH) to review every procedure carried out by their employees which involves contact with a substance hazardous to health including pathogenic micro-organisms.
• Employers and employees (i.e. V.T.s) also have a legal obligation to ensure that any person on the premises (including patients and visitors) is not placed at any avoidable risk, as far as is reasonably practicable.

Reducing Inoculation Injuries

• With due care and good working practices, the risk of experiencing an inoculation injury can be reduced considerably.
• The majority of inoculation injuries sustained in the dental environment are avoidable. For example:
  • Do not re-sheath local anaesthetic needles manually unless:
    • A device is available that allows this to be done with one hand.
    • The barrel of the syringe is held in one hand and the needle cap is scooped up from a flat, hard surface. Only when the needle is covered by the cap should the second hand be used to complete the re-sheathing and secure the needle cap.
  • Cover existing wounds, skin lesions and all breaks in exposed skin with waterproof dressings.
    • Remember that gloves cannot be relied upon to form an intact barrier. The longer that gloves are worn, the more likely that:
      • The number and size of holes in gloves will increase as a consequence of physical trauma.
      • Latex gloves become porous due to hydration of latex.
    • Accordingly, it is essential that:
      • Gloves are changed:
        • Between patients.
        • During long procedures.
        • When damaged.
      • The hands are washed properly each time before gloves are worn.
  • Avoid sharps usage where possible.
  • When sharps have to be used, exercise particular care in handling and disposal.
    • Each member of the team should understand in advance what tasks they are to perform.
      • This requires training and planning.
    • Use approved sharps containers that conform to standards for off-site disposal.
    • Place sharps containers:
      • Out of the reach of children (i.e. not on the floor).
      • As close as is practical to the point of use.
    • Place all disposable sharps in sharps containers immediately after use.
    • Discard disposable items as a single unit where possible, rather than dismantling them into their components.
    • Do not overfill sharps containers.
    • Secure the lids of sharps containers prior to transfer to a licenced authority for subsequent incineration.
    • Replace full sharps containers promptly.
  • Avoid wearing open footwear in situations where blood may be spilt or where sharp instruments or needles are handled.
  • Clear up spillage of blood promptly and disinfect surfaces.
  • Wear gloves:
    • Where contact with blood or other body fluids (e.g. saliva) is anticipated.
    • To clean equipment prior to sterilisation or disinfection.
    • When handling disinfection fluid.
    • When cleaning up spillages.
  • Wear safety glasses.
• Keep yourself updated about best practices.

Immunisation Against Blood-Borne Viruses

• All health care workers (HCWs) who have direct contact with patient's blood or other potentially infectious body fluids or tissues, should be immunised against Hepatitis B.
  • Successful immunisation also provides protection against Hepatitis D (delta agent) which can only replicate in the presence of Hepatitis B infection.
  • Immunisation does not diminish the need to follow rigorous cross-infection procedures.
  • Check the current B.N.F. for more information about hepatitis B vaccine and immunization schedules.
  • Hepatitis B vaccination has been linked to development of oral mucosal lichenoid reactions in a small number of patients.
• To date, no effective vaccines have been produced that prevent
  • HIV infection
  • Hepatitis C infection.

Risk Factors for BBVs

• Prevalence rates of BBVs are higher in certain population groups including:
  • Men who have had sex with men.
  • People who have practiced high risk sexual practices, in particular receptive anal sex.
  • People who have been sexually-promiscuous, including prostitutes.
  • People who have injected drugs intravenously (this may include atheletes who have used performance enhancing drugs).
  • People who have received a blood transfusion, blood products or tissues/organs that have not been screened for BBVs.
  • People who are from parts of the world where BBVs are common.
  • Children of anyone in the above groups.
  • Anyone who has had sex with any of the above groups.

Risks of Transmission of Blood-Borne Viruses in the Health Care Setting

• The risk of transmission of BBV infections is:
  • Greater from patient to HCW, than from HCW to patient.
• The risks to the HCW for each virus is proportional to:
  • The prevalence of that infection in the population served.
    • Identification of patients who fall in to high risk categories are considered above.
  • The infectious status of the individual source patient, which may be known or unknown.
  • The risk of a significant occupational exposure occurring during the procedures undertaken:
    • There are different levels of risk for:
      • Major abdominal surgery compared to a simple dental extraction, or
      • A dental extraction compared to placement of class I restoration.
• The risks of transmission following an inoculation injury to a HCW from an infected patient has been estimated at
  • 1 in 3 when the source patient is infected with Hepatitis B and is e-antigen positive.
    • In the absence of e-antigen, the risks are lower.
  • 1 in 30 for a patient infected with Hepatitis C.
  • 1 in 300 for an HIV positive patient.
    • Transmission of HIV to a HCW is more likely if
      • There is a deep puncture injury or contamination of an exisiting cut.
      • There is a penetrating injury by a device visibly contaminated with blood.
      • Injury occurred with a needle that had previously been placed within a vein or artery of the patient.
      • The patient has end-stage HIV infection.
        
• BBVs can also be spread via contact with mucocutaneous surfaces (e.g. eyes or skin).
  • Transmission risks are lower than for innoculation injuries.
    • For example, the risks of acquiring HIV infection after a single episode of mucocutaneous exposure is less than 1 in 2000.

What to do Following an Innoculation Injury

• DO NOT PANIC.
• Follow the local procedures:
  • Be familiar with these before the innoculation injury occurs!
  • These procedures take account of the interests of both the HCW and the patient.
    • In most, but not all instances, the HCW will be the recipient and the patient the source.
• Do not place others at risk:
  • For example, do not leave sharps where they might result in a second inoculation injury.
• Immediately after exposure:
  • Liberally wash the wound or non-intact skin with soap and water.
    • Do not scrub the wound.
    • Do not suck on the wound, but gently encourage any free bleeding from the wound.
  • Involved mucous membranes (including the eyes) should be irrigated copiously with water (after removing any contact lenses).
    • Do not swallow the irrigant when used in the mouth.
• Then report the incident to the nominated person so that urgent advice can be obtained on further management.
  • Know who this is in advance.
  • Accident and emergency departments are open 24 hours a day and will be able to offer advice over the telephone.
• The designated doctor will:
  • Need, where possible, to obtain information about, or from the source about possible indicators of BBV infection including:
    • Risk factors.
    • Results of previous tests (if any) for HIV and Hepatitis B and Hepatitis C.
    • Medical history suggestive of previous infection.
    • Current and previous anti-viral treatment in patients known to be HIV positive.
  • When indicated, to counsel and then ask the source to consent for testing for BBVs.
  • Evaluate whether the recipient should receive post-exposure prophylaxis:
    • For Hepatitis B this may involve
      • Immediate initiation of immunization in those not previously immunized.
      • A booster dose in those successfully immunized in the past.
    • For HIV this may involve immediate prescription, ideally within one hour, of anti-retroviral drugs.
    • There is no effective prophylaxis against Hepatitis C infection.
• There are inevitable delays before the results of any serology testing (of the donor and recipient) are known. When transmission has occurred, 95% of BBVs will be detectable within 6 months. During this period of uncertainty
  • It is acceptable for the clinician to keep working:
    • The risk of the HCW having become infected occupationally with a BBV is low.
    • Even if the HCW had been occupationally infected, the chances of then passing on that infection in the workplace to either a patient or work colleague are remote.
  • Safer sex should be practiced.
  • The recipient should not donate blood.
• It is a requirement to report the incident under the
  • Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR) 1995.
• The circumstances surrounding the innoculation injury should be investigated and changes implemented to reduce the likelihood of future, similar events.
  • The majority of inoculation injuries are avoidable.
• If a HCW has contracted a BBV in the workplace:
  • The appropriate guidelines should be followed to:
    • Optimise the care of the infected individual.
    • Limit the risk of further spread of infection. This does not necessarily mean that the infected HCW will have to cease working, but modifications to working practices may be required.
  • Compensation may be due from the NHS Injury Benefits Scheme.

Return to Viral Infections Index Page