Risks of HIV infection after accidental occupational exposures
Transmission of HIV is estimated to occur in about 1 in 300 cases of occupational exposure. The factors that increase the risk of transmission of HIV after an occupational exposure are if:
- exposures are deeply penetrating, as opposed to superficial splashes onto mucus membranes (e.g. broken skin, mouth, eyes).
- the injury is caused by a device that was in an artery or vein in the infected person.
- blood is visible on any device involved in the exposure.
- exposure is to a large volume of blood, or other potentially infectious fluids, such as blood plasma, pus or cerebrospinal fluid (from a spinal tap).
- the injury is caused by wet instruments, which have a much higher risk of transmission than with dry instruments.
- hollow bore needles are involved in the exposure; they are more likely than solid needles to bring about transmission of HIV.
- gloves are not used while preparing and giving injections.
- the 'source patient' has advanced HIV disease, taking into account factors such as the clinical stage of the illness, the extent of virus circulating in the blood, and the presence of antiretroviral drugs in their blood. The level of risk relates to the number of viruses present in the infected blood or body fluid involved in the exposure.
Hollow bore needles are used as intravenous (IV) needles or canullae, or to give drug injections. Solid needles are those used in suturing wounds.
From the above list, can you identify circumstances in which the risk of HIV transmission after an occupational exposure will be reduced, relative to these higher-risk criteria?
The risk will be lower if the exposure is onto mucus membranes, not deeply penetrating, or involves body fluids other than blood; and also:
- if the device is dry;
- it is not previously in the patient's vein or artery,
- and/or blood is not visible on the device;
- the device is a solid (not hollow bore) needle;
- the amount of blood transferred is very small;
- gloves are worn;
- the patient is not in an advanced stage of HIV disease.