Percutaneous injury: a needle or other sharp instrument accidentally penetrating the skin. If the needle or sharp instrument is contaminated with blood or other body fluid, there is the potential for transmission of infection.
Mucocutaneous exposure: when blood or other body fluid splashes into the eyes, nose or mouth or onto broken skin. Other potential routes of exposure to blood or other body fluids include bites and scratches.
Occupational exposure: when this injury/exposure occurs in a work context.
Pathogens of Concern
Needlestick injuries account for 40,000 injuries to NHS staff each year. The major blood-borne pathogens of concern are:
- Hepatitis B virus (HBV)
- Hepatitis C virus (HCV)
- Human immunodeficiency virus (HIV).
However, other pathogens also have the potential for transmission through needlestick injury. These include:
- Human T lymphotrophic retroviruses (HTLV I & II)
- Hepatitis D virus (HDV, which is activated in the presence of HBV)
- Epstein Barr Virus (EBV)
- Cytomegalovirus (CMV)
- Malarial parasites
- Parvovirus B19
- Transfusion-transmitted virus (TTV)
- West Nile Virus (WNV)
- Prion agents such as those associated with transmissible spongiform encephalopathies (TSE).
Risk of Acquiring a Blood-borne Virus:
The average risk of acquiring a bloodbourne virus is:
- 1 in 300 for HIV following percutaneous exposure if the source patient is HIV-positive.
- 1 in 30 for HCV following percutaneous exposure if the source patient has detectable HCV RNA.
- 1 in 3 for HBV following percutaneous exposure if the source patient is HBeAg positive.
- 1 in 1000 for HIV following mucocutaneous exposure if the source patient is HIV-positive.
- There is currently no evidence on the risk of transmission for HBV and HCV following mucocutaneous exposure.
Factors Influencing Pathogen Transmission
Higher Risk of Transmission:
- Percutaneous injury.
- A deep injury.
- Injury with a wide bore needle.
- Terminal HIV-related illness in the source patient.
- Visible blood on the device which caused the injury.
- Injury with a needle that had been placed in a source patient’s artery or vein.
- Source patient not immunised against HBV.
- Source patient co-infected with more than one blood-bourne virus.
- No protective equipment used (gloves, double gloves, eye protection).
- First aid measures not implemented (washing, bleeding).
- HCV RNA detectable in source patient on most recent blood test.
- High viral load of HIV in source patient.
- HBeAg detectable in source patient's blood.
Lower Risk of Transmission:
- Mucocutaneous membrane or broken skin exposure.
- A superficial injury.
- Injury with a solid bore needle.
- Source patient immunised against HBV.
- Protective equipment used (gloves, double gloves, eye protection).
- First aid measures implemented (washing, bleeding).
- Low viral load of HIV in source patient.
Immediate Action Following a Needlestick Injury
- For any percutaneous injury, bite or scratch - wash the injury well with soap and running water but without scrubbing. Encourage bleeding – do not suck or immerse in bleach, antiseptics or skin washes which may reduce the body’s local defences.
- For mucocutaneous exposure – irrigate with copious quantities of cold water.
- Promptly report the injury. A risk assessment should be made by someone other than the exposed healthcare worker about the appropriateness of starting post-exposure prophylaxis (PEP).
- Note the name, address and clinical details of the source patient.
- Since 1997, national surveillance of occupational health exposure to blood-borne viruses has been in place. Report the incident to Occupational Health and fill in an incident form.
- Store blood from both parties.
Taking Blood from the Source Patient: Ethics and Principles
- When a source patient is asked to agree to undergo informed HIV testing, careful pre-test discussion will be needed, as well as informed consent, which should include disclosure of the source patient’s test result to the occupational health service and to the health care worker.
- The source patient should be informed about the incident and the reason for the enquiry, request for a test and to whom the results will be disclosed.
- This pre-test discussion can be provided by any appropriately trained and competent health care worker but not the exposed worker.
- Specialist pre-test discussion may sometimes be considered appropriate if there are unusual circumstances, for example if the source patient does not speak English or has learning difficulties.
- The Human Tissue Act 2004 allows any material containing cells including tissue, whole blood and other body fluids to be used to obtain medical information about a patient which may affect another person ‘if done with appropriate consent’. Where a source patient lacks capacity to consent (e.g. because they are unconscious), this material can only be tested for blood bourne viruses if it is held to be in their best interests in accordance with the Mental Capacity Act 2005. In this situation, advice should also be sought from a medical defence organisation.
- It is recommended good practice that all hospitals have the capacity to obtain an HIV test result within 8 hours and not more than 24 hours after source blood is taken.
- Any source patient who is newly diagnosed HIV positive as a result of this process will need immediate access to specialist post-test counselling. Close support and clinical management will be needed on an ongoing basis. Source patients should also be informed promptly of HIV negative results.
Risk Assessment of the Source Patient
1. Is the blood-bourne virus status known or unknown?
2. If unknown, is there any indication of the origin of the sharp or body fluid? For example, was the sharp from an area with patients known to have HBV/C or HIV?
3. If known, has the source patient been recorded as having a HBV, HCV or HIV infection? The validity of negative results varies depending oncurrent risks factors and how old the test results are.
4. If the source patient is not known to carry any of these viruses, do they have any risk factors for them?
5. Risk factors for HIV include: living in sub-Saharan Africa, men who have sex with men, intravenous drug users, people with HIV-infected mothers or with HIV-infected sexual partners. If the source patient is known to be infected with HIV:
- Are they terminally ill with HIV-related disease? (if so viral load may be high).
- Has there been a recent/current seroconversion illness?
- What is the most recently recorded viral load?
- Are they taking anti-retrovirals?
- Is there any evidence of viral drug resistance?
6. Risk factors for HCV include: receipt of unscreened blood or untreated plasma products (before September 1991 and 1985 respectively in the UK) and sharing of needles while using reacreational drugs.
If the source patient is known to be infected with HCV, is HCV RNA detectable on the most recent test?
7. Risk factors for HBV: intravenous drug users, men who have sex with men and people with HBV-infected mothers or HBV-infected sexual partners.
If the source patient is known to be infected with HBV, are they HBsAg or HBeAg positive?
Post-Exposure Prophylaxis (PEP)
- PEP is initiated in line with guidance from the UK Chief Medical Officers’ Expert Advisory Group on AIDS. Anti-retrovirals are initiated for prophylaxis if the risk of HIV infection is considered high.
- PEP has been shown to reduce the seroconversion rate by 80%. Evidence from animal models indicates that systemic viral dissemination does not occur immediately, leaving a window of opportunity during which post-exposure anti-retroviral medication may be beneficial.
- PEP is not a licensed indication for any of the anti-retroviral drugs, which are therefore prescribed on an ‘off-label’ basis.
- Anti-retroviral agents from three classes of drug are currently licensed for first-line treatment of HIV:
- nucleoside/nucleotide analogue reverse transcriptase inhibitors (NRTIs)
- non-nucleoside reverse transcriptase inhibitors (NNRTIs)
- protease inhibitors (PIs)
- Zidovudine (NRTI) is the only drug for which there is evidence of a reduction in risk of HIV transmission following occupational exposure.
- Combinations of anti-retrovirals are more potent than zidovudine alone in suppressing viral replication. There is also a rise in prevalence of drug resistance amongst HIV-infected individuals and this has led to combination anti-retroviral drug prophylaxis following occupational exposure to HIV.
- PEP starter packs usually have:
- One Truvada tablet (300mg tenofovir and 200mg emtricitabine) once a day plus
- Two Kaletra film-coated tablets (200mg lopinavir and 50mg ritonavir) twice a day.
- All of the anti-retroviral agents have side effects including nausea, diarrhoea, dizziness and headache. Patients can be advised to take the tablets with food to reduce these side effects.
- Anti-retrovirals interact with many drugs include the oral contraceptive pill (OCP), statins, erythromycin, St John's Wort, rifampicin, systemic lidnocaine and quinidine. Ecstasy use can be fatal.
- Women are advised to use barrier contraception as the OCP may be ineffective, although both the copper and Mirena coil remain effective. Pregnant women can use PEP, but may require a tailored package and more frequent blood tests.
- Currently, it is not possible to prevent HCV infection after exposure. HCV infections remain asymptomatic in up to 85% of cases. Therefore, appropriate testing at the correct time intervals is recommended to detect a potential case of HCV seroconversion.
- The exposed person should also be advised to have safe sex for three months, not to donate blood until all necessary screening tests are clear and to see their GP if they develop pyrexia.
References and Useful Resources
- Needlestick Injuries. NHS Employers, 2009.
- Longmore M, Wilkinson I, Turmezei T and Cheung CK. 2008. Oxford Handbook of Clinical Medicine. 7th Ed. Oxford University Press.
- Short Life Working Group on Needlestick Injuries in NHSScotland. Needlestick injuries: sharpen your awareness—needlestick injuries in the NHSScotland. Edinburgh: Scottish Executive, 2001.
- Eye of the Needle. United Kingdom Surveillance of Significant Occupational Exposures to Bloodborne Viruses in Healthcare Workers. Health Protection Agency, November 2008.
- HIV post-exposure prophylaxis. Guidance from the UK Chief Medical Officers’ Expert Advisory Group on AIDS, Department of Health, September 2008.
- UK Health Departments Guidance for Clinical Health Care Workers: Protection against Infection with Blood-borne Viruses. Recommendations of the Expert Advisory Group on AIDS and the Advisory Group on Hepatitis. Accessed on 2/4/2012 at: http:/www.open.gov.uk/doh/chcguid1.htm.