What are the three major elements in preventing exposure to bloodborne pathogens?

Preventing occupational exposure to and infection from bloodborne pathogens is a key element of injection safety. Thus, such prevention is an important part of any comprehensive programme for protecting health workers and patients.

The main interventions that are needed to prevent exposure and infection are:

• basic occupational health care, including immunization and awareness of current health status;

• prevention of needle-stick injuries and other blood exposures;

• management of exposures to blood; this includes PEP.

Each of these interventions is discussed below.

4.1. Basic occupational health care

4.1.1. Immunization against hepatitis B

WHO considers universal immunization to be the most effective preventive measure against diseases induced by infection with hepatitis B. Strategies include:

• integration of hepatitis B vaccine (HepB) into routine infant immunization programmes (13, 61);

• provision of a HepB dose at birth to prevent perinatal transmission (13, 61);

• vaccination of those at risk, including health workers (with a catch-up vaccination).

All health workers – including waste disposal workers, and emergency and safety workers exposed to the risk of bloodborne pathogens – are at risk of exposure. They should be immunized either before training or as soon as possible when at work, unless they are already immunized (15).

The World Health Assembly has resolved that all health workers should be protected from infection with HBV by receiving immunization for hepatitis B early in their careers (15).

Vaccines are widely available that are safe, cost effective and meet the current WHO quality requirements (13).

Routine immunization of health workers against infection with HBV is recommended.

• Pre-vaccination serological testing is unnecessary.

• Many different schedules are available. A schedule including three doses at 0, 1 and 6 months is highly effective; it provides long-term protection in most individuals. The usual adult dose is 1.0 ml (twice the monovalent paediatric dose of 0.5 ml) and the vaccine is administered intramuscularly.

• Serological testing at 2–6 months after the third dose of HBV vaccine can demonstrate whether an antibody response has developed against hepatitis B surface antigen (62).

4.1.2. Testing for HBV, HCV and HIV

All health workers should have access to the tests available for HBV, HCV and HIV infection. If they know their own status for these infections, health workers can access treatment and care if necessary. Also, in cases of exposure to HBV, HCV or HIV, test results provide baseline information on immune status; this is critical for the safe and efficient management of the postexposure procedures available for hepatitis B and HIV.

Any testing should be undertaken in conditions that respect the worker's rights and is based on informed consent. These conditions are described in guidelines developed by the International Labour Organization and WHO, on health services and HIV/AIDS (63).

4.2. Prevention of needle-stick injuries and other blood exposures using a hierarchy of controls

Methods used to control occupational hazards have traditionally been discussed in terms of a hierarchy and presented in order of priority. A hierarchy of controls to prevent needle-stick injuries and other blood exposures is given below by order of effectiveness (most effective first) (64, 65).

• Elimination of hazard – Complete removal of a hazard from the work area is the most effective way to control hazards; this approach should be used whenever possible. Examples include (24, 66):

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  removing sharps and needles when possible (e.g. by substituting jet injectors for needles and syringes, or using needleless intravenous systems);

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  eliminating all unnecessary injections;

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  eliminating unnecessary sharps such as towel clips.

• Engineering controls – These are used to isolate or remove a hazard from a workplace. Examples include (33, 67-69):

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  sharps disposal containers;

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  when possible, use of sharps protection devices for all procedures (devices with needles that retract, sheathe or blunt immediately after use).

• Administrative controls – These are policies, such as SOPS, which aim to limit exposure to the hazard. Examples include (1, 62):

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  allocation of resources demonstrating a commitment to health-worker safety;

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  a needle-stick injury prevention committee;

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  an exposure control plan;

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  removal of all unsafe devices;

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  consistent training on the use of safe devices.

• Work practice controls – These are controls to change the behaviour of workers, to reduce exposure to occupational hazards. Examples include (1, 62):

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  no needle recapping;

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  placing sharps containers at eye level and within arms' reach;

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  sealing and discarding sharps containers when they are three quarters full;

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  establishing means for the safe handling and disposal of sharps devices before beginning a procedure.

• Personal protective equipment – These provide barriers and filters between the worker and the hazard. They will prevent exposures to blood splashes but will not prevent needle-stick injuries (34, 70, 71). Examples include eye goggles, gloves, masks and gowns.

4.3. Overview of management of exposure to blood

This section discusses management of occupational exposure to blood and other potentially infectious material. The exposure can occur through needle-stick and sharp injuries, and from splashes contaminated with blood or body fluids. Management includes first aid, risk assessment, notification and reporting for HBV, HCV and HIV, and provision of PEP. The prophylaxis should be administered as soon after exposure as possible; it entails medical evaluation, follow-up care and prevention, and is specific to the etiologic agent involved (43).

The risks of transmission of infection from an infected patient to the health worker following a needle-stick injury are estimated to be (6):

• hepatitis B – 3–10% (up to 30%);

• hepatitis C – 0.8–3%;

• HIV – 0.3% (mucous membrane exposure risk is 0.1%).

Factors that can increase the risk of transmission of HIV include a deep wound, visible blood on the device, a hollow-bore blood-filled needle, use of the device to access an artery or vein, and high-viral-load status of the patient (6, 63). Together, these factors can increase the risk of transmission of HIV from a contaminated sharp to 5%.

The box below summarizes the steps to take in case of occupational exposure to blood. The management of exposure to specific agents (HBV, HCV and HIV) is discussed in detail below. In all cases, the person who has been exposed to potentially infectious material should be counseled; where PEP is available, the counselling should include the decision on whether or not to take PEP.

Box 4.1

Steps to take in cases of occupational exposure to blood. Apply first aid care, as appropriate (see Section 4.3.1, below). Notify a supervisor. The health-care worker should report immediately to the medical services and seek advice on the need for PEP (more...)

4.3.1. First aid

The first aid given is based on the type of exposure (e.g. splash, needle-stick or other injury) and the means of exposure (e.g. intact skin, nonintact skin) (14, 72). Table 4.1 shows the first aid to apply in different situations.

Table 4.1

First-aid care of the exposure site.

4.3.2. Notification

The health-care worker should report immediately to the medical services and seek advice on the need for PEP for HIV and HBV.

4.3.3. Risk assessment

In managing exposure, the first step is to carry out an immediate medical evaluation, including a risk assessment (72).

To assess the risk of transmission from the exposure:

• determine the risk associated with the exposure by considering the

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  type of fluid (e.g. blood, visibly bloody fluid, other potentially infectious fluid or tissue and concentrated virus);

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  type of exposure (i.e. percutaneous injury, mucous membrane or nonintact skin exposure and bites resulting in blood exposure);

• evaluate the risk associated with the exposure sources by

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  assessing the risk of infection for all bloodborne pathogens using available information (e.g. interview, medical records);

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  perform tests on the source person based on informed consent, but DO NOT test discarded needles or syringes for virus contamination;

• combine the results to evaluate the risk to the exposed person.

Ensure that only a suitably trained person performs the medical evaluation, risk assessment and prescription of PEP.

Where logistic reasons (e.g. testing facilities not being readily available) make it difficult to evaluate the immune status of the person exposed, it may be useful to withdraw and store a blood sample, to help in obtaining baseline information. However, only do this if the exposed person gives informed consent.

Give PEP, even if test results are not yet available.

4.4. Evaluation and management of exposure to HBV

4.4.1. Risk of transmission of HBV

The risk of transmission of HBV is higher than that for HCV or HIV. Among susceptible health workers, the risk of HBV infection after a needle-stick injury involving an HBV-positive source is 23–62% (6, 14).

4.4.2. Management of HBV exposure

PEP for HBV can be highly effective in preventing transmission of the virus after exposure. PEP for HBV is based on the hepatitis B vaccine, either alone or combined with hepatitis B immune globulin (HBIG).

• For PEP to be effective, the initial dose of vaccine must be administered soon after exposure; the longer the gap between exposure and administration of the vaccine, the less effective the PEP.

• Few studies have researched the maximum time after exposure during which PEP is effective, but it is likely to be less than seven days for needle-stick exposures (14).

The steps to take after HBV exposure are to:

• evaluate the exposed person for HBV – assess the person's immunization status for hepatitis B (i.e. by taking their history of hepatitis B vaccination);

• administer HBV PEP for exposures that pose a risk of infection transmission.

WHO has no specific guidelines for HBV PEP; however, it does recommend HBV PEP (73). This document refers to the CDC guidelines (14). As shown in Table 4.2, the regimen recommended for HBV PEP depends on the vaccination status of the exposed person. HBV PEP is safe for pregnant and lactating women.

Table 4.2

Hepatitis B post-exposure prophylaxis and immunization follow-up in occupational settings.

4.4.3. Follow-up of HBV exposure

Perform follow-up testing for antibodies to hepatitis B in individuals who receive hepatitis B vaccine in response to an exposure. The recommendation is to test for antibodies 1–2 months after the last dose of vaccine. However, if the person received hepatitis B immune globulin in the previous 3–4 months, it is not possible to use the test for antibodies to hepatitis B to determine the response to the vaccine.

4.5. Evaluation and management of exposure to HCV

4.5.1. Risk of transmission of HCV

The risk of transmission of HCV is relatively low. The seroconversion rate after accidental percutaneous exposure from an HCV-positive source is 1.8% (range: 0–7%), and one study indicated that transmission occurred only from hollow-bore needles. HCV is rarely transmitted from exposure of mucous membranes or nonintact skin to contaminated blood (14, 16).

4.5.2. Management of exposure to HCV

There is no recommended PEP for exposure to HCV-positive blood. Immunoglobulin and antiviral agents are not recommended as PEP, and there is no vaccine against HCV. Instead, the procedure is to identify infection as soon as possible and refer the person for evaluation of treatment options.

There are no guidelines for administration of therapy during the acute phase of hepatitis C. However, a few studies suggest that antiviral therapy might be beneficial when started early in the course of the infection.

The steps to take after HCV exposure are simply to perform baseline testing for antibodies to HCV and for alanine aminotransferase (ALT).

4.5.3. Follow-up of HCV exposure

Perform follow-up testing for individuals potentially exposed to HCV.

• Test for anti-HCV and ALT 4–6 months after exposure.

• Test for HCV ribonucleic acid (RNA) at 4–6 weeks if early diagnosis of HCV infection is desired.

• Confirm repeatedly positive results in anti-HCV enzyme immunoassays (EIAs) with supplemental tests.

If an individual has seroconverted, refer the person to a specialist.

4.6. Management of exposure to HIV

4.6.1. Risk of transmission of HIV

The risk of acquiring HIV infection following an exposure through the skin (i.e. percutaneous) to blood known to be infected with HIV is approximately 0.3% (14). This figure is derived from studies carried out in well-resourced countries with a low background prevalence of HIV. The risk may be greater in countries with higher prevalence or in settings that have limited resources, where the reuse of medical supplies and equipment is higher and overall safety standards are lower.

4.6.2. Management of exposure to HIV

Refer the person exposed to the risk of transmission to a trained person for medical evaluation, risk assessment and prescription of PEP. The decision on whether or not to take PEP should be based on the recommendations shown in Tables 4.3 and 4.4, appropriate information, and counselling on adherence and on the possible adverse reactions to the antiretroviral drugs.

Table 4.3

HIV post-exposure prophylaxis following occupational exposure.

Table 4.4

Evaluation of risk of HIV infection.

Testing and counselling

For people potentially exposed to HIV, testing is highly recommended but should never be mandatory (76).

• If testing is available, offer a test, but ensure that the person receives appropriate counseling, with the option to opt out of testing.

• Where possible, also test the source patient, with that person's informed consent.

• DO NOT delay the administration of antiretroviral drugs for PEP while waiting for test results.

• If the test results of the source person are negative, consider stopping PEP.

Issues to raise in PEP counselling include:

• the importance of treatment adherence;

• the importance of HIV prevention in general and at the workplace;

• recommendations on the use of condoms and the avoidance of donating blood, sperm or organs until a test at 6 months after exposure is negative;

• information on contraception for women of childbearing age;

• information on alternatives to breastfeeding for lactating mothers.

Administration of PEP

Do not administer PEP to a person who is HIV positive, because PEP generally includes only two drugs to be taken for only 28 days, and is thus not a treatment for HIV infection. HIV treatment is based on a combination of three antiretroviral drugs taken continuously. If desired, it is acceptable to administer antiretroviral drugs for PEP, and to stop the treatment if the exposed person is found to be HIV positive.

In situations where PEP is required:

• administer the antiretroviral drugs for PEP as soon as possible after the exposure (ideally within 4 hours);

• continue the PEP regimen continuously for 28 days;

• use the two-drug regimen (recommended by WHO) unless there is suspicion or evidence of drug resistance, or unless there are national guidelines on choice of PEP regimen (in which case, follow these in preference);

• evaluate the person taking PEP within 72 hours, to monitor for possible adverse drug reactions and adherence, and follow-up (as described below) for at least two weeks.

HIV PEP standard drug regimen

Table 4.5 shows the WHO recommended two-drug combination therapies for PEP for HIV exposure.

Table 4.5

WHO recommended two-drug regimens for HIV post-exposure prophylaxis.

As explained above, in cases where the source person is known to be HIV positive with drug resistance, or in settings where the drug resistant HIV prevalence is above 15%, a three-drug regimen with the addition of a protease inhibitor is recommended. Possible regimens are given in Table 4.6.

Table 4.6

WHO recommended three-drug regimens for HIV post-exposure prophylaxis.

When giving PEP:

• DO NOT prescribe certain combinations of medication (e.g. didanosine + stavudine) for women of childbearing age unless a pregnancy test is negative;

• DO NOT prescribe non-nucleoside reverse transcriptase inhibitors for PEP;

• ensure that lactating women are aware that antiretroviral drugs are present in breast milk and that the virus itself could be transmitted through breastfeeding;

• when and where alternatives to breastfeeding are feasible, discuss this with the mother.

4.6.3. Follow-up of HIV exposure

An exposed health worker should seek or be referred for medical follow-up (77).

• The aim of follow-up visits is to:

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  support adherence to PEP;

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  prevent or treat side effects of PEP;

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  identify a possible seroconversion.

• Test for HIV antibodies at baseline, 6 weeks and 6 months after exposure.

• Test for HIV antibodies if illness compatible with an acute retroviral syndrome occurs.

• Repeat the test for HIV antibodies at 6 weeks and 6 months after exposure; if seroconversion occurs, refer the exposed person for treatment, care and support.

• Advise anyone who has been exposed to use precautions to prevent secondary transmission during the follow-up period; such precautions include:

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  avoiding pregnancy;

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  seeking safe alternatives to breastfeeding;

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  avoiding blood, tissue or sperm donation, and using condoms for sexual intercourse until a test at 6 months shows that the exposed person remains seronegative.

• Evaluate individuals taking PEP within 72 hours, to monitor for possible adverse drug reactions and treatment adherence. Follow up for at least two weeks.

Reporting of HIV exposure

Reporting of the incident should lead to the evaluation of the safety of working conditions and appropriate measures when relevant. All reports should be strictly confidential.

Prompt reporting of exposures is important to:

• ensure timely and appropriate PEP and follow-up;

• provide information useful for future prevention; for example, information about the circumstances of the exposure can be used to evaluate the occupational health programme and make recommendations for changes in products, practices and policies;

• document the injury in the case of seroconversion;

• monitor the frequency of needle-stick injuries and exposure events by person, place and time, as part of occupational exposure surveillance.

The data collected are of two kinds:

• data for risk assessment and post-exposure management;

• data that describe the circumstances of the exposure; these are used for making recommendations for future prevention.

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