Health care workers (HCW) are at risk of acquiring HIV infection at the work place due to contact with body fluids from patients which may contain the virus. To prevent this from happening, HCW need to adopt universal precautions in their dealing with all patients and also in the handling of all body fluids. This includes amongst others, careful diposal of sharp objects e.g. needles and scalpels, and the use of protective barriers e.g. gloves and eye glasses.

Body fluids that have been implicated in the transmission of HIV include:

• Semen
• Vaginal secretions
• Breast milk
• Blood or other body fluids visibly contaminated with blood.

Transmission of HIV through cerebrospinal, synovial, pleural, pericardial and amniotic fluids has not been determined. In the same vein, even though the virus has been found in urine, tears, sweat and saliva, the infectiousness of these body fluids has not been determined. Nevertheless, these body fluids need to be handled with care.

Exposures at the work place that place HCW at risk of HIV infection include:

• Percutaneous injury i.e. a needle stick injury or cut with a sharp object
• Contact of mucous membranes (e.g. eyes) with body fluids
• Contact of non-intact skin (chapped, abraded, or skin afflicted with dermatitis) with body fluid
• Contact of intact skin with body fluid when the duration of contact is prolonged

Other factors that put the HCW at risk of HIV infection include a deep injury with a sharp instrument when there is visible blood on the device causing the injury, when the device has previously been placed in the source patient’s vein or artery (e.g. after a venepuncture), and when the source patient dies of an AIDS related illness.

Management of exposure

Not all exposures to HIV contaminated body fluid end up in HCW infections. It is estimated that the risk of transmission after percutaneous injury is 0.3% and 0.09% after a mucous membrane exposure. The risks after skin exposure to HIV infected blood is < 0.1%. The majority of exposures therefore do not lead to infection.

Thus, in the management of an exposed HCW it is important to evaluate the type of exposure (percutaneous, mucous membrane, skin), source material (blood, peritoneal fluid, urine etc), severity of exposure (deep injury, size of exposed surface, quantity of body fluid, integrity of skin), and HIV status of source material. The highest risk exposures are from a large volume of blood (e.g. deep injury with large diameter hollow needle previously in source patient’s vein or artery) and when the source patient is known HIV positive.

Health facilities need to keep a log book of records of such accidental exposures and periodically audit the records and plan preventive strategies to forestall such accidents.

Management of the exposed site includes:

• Washing wounds and skin sites that have been in contact with blood or body fluids with soap and water

• Flushing mucous membranes with water

There is no evidence that the use of antiseptics for wound care or expressing fluid by squeezing the wound further reduces the risk for HIV transmission.

As mentioned previously, the only way of preventing occupationally acquired HIV infection by HCW is the adoption of universal precautions at the work place.

Post exposure prophylaxis (PEP)

Within 24-48 hours of exposure, antiretroviral therapy when given may be able to prevent infection. It is important that it is initiated as soon as possible after the exposure (preferably within 1-2 hours).

The antiretrovirals used are potentially toxic, and PEP does not always work. In consideration for the initiation of PEP therefore, issues discussed above including nature, and type of exposure and HIV sero-status of source patient need to be addressed. When the sero-status of the source patient is not immediately known, PEP if deemed necessary, should be started, pending HIV antibody testing of source patient after appropriate counselling. If test results turn out negative, stop PEP. Otherwise it should be continued for 4 weeks. Patients taking PEP need to be counselled among other things on adherence to treatment, the toxicity of the drugs used and also that PEP may not prevent HIV infection all the time.

PEP needs to be initiated quickly when there is a recognised risk. Health facilities are therefore advised to keep emergency stocks of PEP medication, and designate a responsible official who can be called upon at all times to evaluate the risk, counsel a patient and start PEP.

Assessment of exposure risk

• Low risk exposure is described as:

• Exposure to a small volume of blood or blood-contaminated fluids from asymptomatic HIV-positive patients with low viral load

• An injury with a solid needle

• Any superficial injury or mucocutaneous exposure

• High risk exposure is described as:

• Exposure to a large volume of blood or potentially infectious fluid

• Exposure to blood or blood contaminated fluids from a patient with a high viral titre i.e., in the AIDS phase or early sero-conversion phase of HIV

• Injury with a hollow bore needle

• Deep and extensive injury exposure

INVESTIGATIONS

Baseline tests:

• Full blood count
• Liver and renal function tests
• Hepatitis B surface antigen
• HIV serology/PCR if available

Two weeks:

• Full blood count
• Liver and renal function tests

Six weeks:

• HIV serology

Three and Six months:

• HIV serology

TREATMENT

The drugs and regimen used for PEP include:

(Evidence rating: A)

Low risk exposure:

Zidovudine, oral, 300 mg 2 times daily for 28 days plus

Lamuvidine, oral, 150 mg 2 times daily for 28 days

High risk exposure:

Zidovudine, oral, 300 mg 2 times daily for 28 days plus

Lamuvidine, oral, 150 mg 2 times daily for 28 days plus

Nelfinavir, oral, 750 mg 3 times daily (or 1250 mg 2 times daily) for 28 days