20th February 2024

HIV

It is crucial to be sure of the source’s HIV status prior to commencing treatment. Post-exposure prophylaxis (PEP) and blood test monitoring are considered post-exposure. The combined HIV Ag/Ab test is used to monitor the development of HIV, and this is performed at baseline and three months post-exposure. The source’s serology should also be obtained to confirm/exclude the presence of HIV or other BBVs. PEP is often commenced prior to the results of the source’s HIV status if it is unknown. 

The British HIV Association (BHIVA) recommends against the use of post-exposure prophylaxis in cases where the needlestick injury has occurred from a discarded needle in the community. This is due to the difficulty in determining the index cases’ HIV status and the needle use, making the risk of acquiring HIV through this scenario negligible. 

If the index case’s HIV status is unknown or unobtainable, the likelihood of the index case being positive should be estimated based on the patient’s demographics and location. In cases where the probability of HIV transmission is felt to be low, PEP is not indicated. If the source is from a high-prevalence country or a high-risk population, this usually requires a discussion between the clinician and patient about the risks and benefits of PEP. This is because even in this population, the risk of transmission remains low. 

If the index case is positive, it is essential to know if the patient’s viral load is known. Index cases established on antiretroviral therapy with an undetectable viral load within the last six months are felt to be of low risk of transmission. PEP is not recommended in this case. 

If the viral load is elevated or unknown, PEP is recommended in most cases of occupational exposure. However, if the exposure has occurred on intact skin, PEP is not recommended. HIV transmission via human bites is variable, and PEP is usually not recommended in this case unless the following are fulfilled:

• Biter’s saliva was visibly contaminated with blood
• Biter is known or suspected to have an HIV viral load >3.0 log copies/ml
• Bite has resulted in severe/deep structure injuries. 

PEP is usually commenced within the first 72 hours but should be commenced as soon as possible following the exposure. PEP is not recommended beyond 72 hours post-exposure and should be taken for 28 days. A standard PEP regime includes two nucleoside reverse transcriptase inhibitors and an integrase inhibitor. Protease inhibitors may also be used as an alternative. Examples include tenofovir disoproxil/emtricitabine with raltegravir. Patients should be warned of potential side effects and drug interactions while on PEP.