A USER'S GUIDE

Preventing & Treating Occupational Exposure to HIV

INTRODUCTION

The human immunodeficiency virus (HIV) is transmitted from person to person via the following routes:

• Sexual contact during which body fluids are exchanged.
• Transfusion of infected blood and blood products.
• Perinatal transmission from mother to child.
• Contact with infected needles and body fluids.

Medical personnel caring for HIV-infected patients may be at risk for acquiring HIV infection through contact with HIV-infected blood and body fluids. This is referred to as ‘occupational exposure’ to HIV.

All healthcare workers (HCWs) who come in contact with blood or bloody fluids of HIV-infected patients in hospitals or laboratories are at risk for occupational exposure to HIV. This includes nurses, laboratory workers, doctors, residents, paramedical staff, emergency doctors, medical students and others.

The risk varies depending on the type of exposure. A percutaneous injury refers to an injury resulting from a needle prick, or a cut with a sharp object. The risk after percutaneous exposure is estimated to be about 0.3% i.e. 3 out of a thousand needle pricks may result in HIV infection.

The risk after a mucous membrane exposure is estimated to be lower, about 0.09%. This includes contact with the mucous membranes of the eyes, nose and mouth, or contact with chapped, abraded or inflamed skin.

Any kind of direct contact with concentrated HIV in a laboratory is also considered risky.

Contact of HIV-infected blood with intact skin for a prolonged period, or over an extensive area of the skin, may carry a risk, although isolated skin exposure for a short period probably does not pose a risk.

Till June 1997, 52 documented cases and 114 possibly occupationally acquired cases were reported to the Centers for Disease Control (CDC) in the USA. Of the 52 documented episodes, 47 HCWs were exposed to HIV-infected blood, one to a visibly bloody fluid, one to an unspecified fluid, and three to concentrated virus in a laboratory. Forty-five exposures were percutaneous, and five were mucocutaneous. Of the percutaneous exposures, the objects involved were a hollow-bore needle (41 cases), a broken glass vial (2 cases), and a scalpel (1 case).

Needle prick injuries are common among nurses. Percutaneous and other exposures are also common during surgical procedures. Factors posing a risk to the surgeon are the length of the procedure, the volume of blood loss, and whether the operation involves major vascular or intraabdominal gynecologic surgery.

Which factors influence the risk?

Various factors increase the risk of acquiring HIV infection. These include:

• The depth of the injury (in case of a sharp object).
• Whether the device was visibly contaminated with blood.
• Whether the procedure involved placing a needle directly in an artery or vein.
• Whether the needle was a hollow bore needle or a solid needle (e.g. suture needle).
• The size of the needle (large versus small gauge).
• The patient’s viral load (i.e. amount of HIV in circulation).
• The amount of blood or infectious fluid involved in the exposure.
• The duration of the exposure.

Blood and bloody fluids are considered infectious. Potentially infectious materials include semen, vaginal secretions, CSF, pleural, peritoneal, pericardial, amniotic fluids or tissue. Exposure to saliva, tears, sweat, non-bloody urine or faeces is not believed to pose a risk.

The most frequent areas of contact are the hands. Face contacts are common in orthopaedics and obstetrics. Eye or mucous membrane contacts may occur in cases where there is splattering of blood.

There are several preventive measures to reduce the risk of HIV transmission. These include:

• The use of universal precautions.
• The use of two pairs of gloves by surgeons. The obstetrician may use  barriers such as face shields, impervious gowns and impervious shoe covers. Goggles can prevent eye contact.
• Care should be taken during procedures such as endoscopy, ENT surgery, and other situations where splattering of blood is anticipated.
• The use of impervious needle-disposal containers.
• Transport of samples in sealed containers.

Contingency plans for dealing with occupational exposures in hospitals should be available. These include:

• Protocols for evaluation, counseling and treatment of occupational exposures.
• Access to clinicians during all working hours.
• Availability of antiretroviral agents on-site or easily.
• Availability of trained personnel for post-exposure counseling.

How is an occupational exposure evaluated?

An occupational exposure is evaluated based on the following factors:

• What is the source material?
• What is the risk of exposure?
• What is the status of the source person/specimen? (HIV positive, end-stage disease, primary HIV infection, unknown)
• Is the HCW pregnant?

The immediate measures to be taken after an occupational exposure include:

• Use soap and water to wash any wound or skin site that came into contact with infected blood or fluid.
• Flush exposed mucous membranes with water.
• Irrigate an open wound with sterile saline or disinfectant solution.
• Eyes should be irrigated with clear water, saline or sterile eye irrigants.
• Report to the concerned authority.
• Counseling.
• Use antiretroviral therapy.

The term ‘post-exposure prophylaxis’ (PEP) refers to treatment of occupational exposures using antiretroviral therapy. The rationale is that antiretroviral treatment which is started immediately after exposure to HIV may prevent HIV infection.

What are the current guidelines for PEP?

The currently recommended guidelines state that:

• Therapy should be recommended after exposure.
• All regimens must include zidovudine.
• Therapy should be initiated within one to two hours of exposure.
• If the source patient’s HIV status is unknown, decide whether to give PEP on a case-to-case basis.
• Follow-up counseling and HIV testing should be carried out periodically for at least 6 months (i.e. at baseline, 6 weeks, 12 weeks and 6 months). It is estimated that 95% of HCWs seroconvert within 6 months of exposure.

What are the recommended regimens for PEP?

POST EXPOSURE PROPHYLAXIS FOR HCWs

* See text
† Consider PEP if extensive area was exposed or if prolonged contact with blood occurred.

The following table lists the drugs, dosages and duration of therapy for both the Basic and Expanded regimens.

Extensive data on zidovudine indicate that it is safe and well-tolerated when used after 14 weeks of gestation in HIV-infected women. Limited data on the use of lamivudine alone or in combination with zidovudine indicate that lamivudine is safe during pregnancy for women and infants although long-term safety is not known.

Studies conducted in animals and in humans prove the efficacy of PEP regimens. Zidovudine has been the most widely studied agent for prophylaxis. A retrospective study of HCWs who used zidovudine as PEP found that the risk of HIV infection was reduced by approximately 81%.

Although the efficacy of combination regimens for PEP is unknown, combination drug regimens are currently recommended for PEP. This is because they are more potent and may be more effective against drug-resistant strains.

Information about the toxicity of antiretroviral drugs in persons without HIV infection is limited. HCWs who are given PEP need to be monitored for drug toxicity at baseline (on starting PEP), and two weeks after therapy begins. They should be advised to report acute illness and symptoms such as back or abdominal pain, pain on urination, blood in the urine, increased thirst and frequent urination. If these symptoms are reported, they must be evaluated immediately.

Nausea and diarrhoea often occur during the course of treatment. Prescribing antimotility and/or antiemetic agents or other medications for specific symptoms may enable the exposed HCW to complete PEP without changing the regimen. Alternatively, modifying the dose interval (administering a lower dose of the drug more frequently throughout the day) may help.

Exposed HCWs should avoid behaviours that carry a risk of secondary transmission of HIV for the duration of the follow-up period. This is especially true for the first 6 to 12 weeks after exposure, when seroconversion is most likely to occur.

The exposed HCW should be advised on the following:

• Sexual abstinence
• Use of condoms to prevent sexual transmission and pregnancy
• Not to donate blood, plasma, organs, tissue or semen

HIV and some drugs used in therapy can pass through breast milk. Consider discontinuing breast-feeding, particularly after high-risk exposures

Occupationally acquired HIV infection represents a significant health hazard for HCWs caring for HIV-positive patients. It is important to institute measures to reduce such risks, as also establish protocols for treating exposed HCWs.

Current guidelines recommend commencing prophylactic therapy immediately after an exposure, which poses a risk of transmitting HIV infection. Zidovudine is a necessary component of the prophylactic regimen. Counseling also has a very important role to play.

References:

1. Consultant Jan 1999, p 230-36.
2. MMWR May 15, 1998, Vol 47, No. RR-7.