Which of the following scenarios is most likely associated with the lowest risk of HIV transmission to a health care provider after an accidental needle stick from a patient with HIV?
The needle is visibly contaminated with the patient's blood.
The needle stick injury is a deep tissue injury to the health care provider.
The patient whose blood is on the contaminated needle has been on antiretroviral therapy for many years with a history of resistance to many available agents but most recently has had successful viral suppression on current therapy.
The patient whose blood is on the contaminated needle was diagnosed with acute HIV infection 2 weeks ago.
The quoted risk for HIV transmission via a needle stick is 0.3%. This risk can be reduced to less than 0.1% if the at-risk health care worker is treated with antiretroviral therapy within 24 hours. The risk of transmission is likely highly variable according to a number of factors. Large-bore needle sticks where infected patient blood is visible are higher risk, as are deep tissue puncture to the health care provider. The patient's degree of virologic control is generally inferred to be critical as well. Patients with viral loads below 1500/mL are considerably less likely to transmit via a needle stick than those with high viral loads. An extension of this point is that during acute and end-stage HIV infection, viral loads are extremely high, and contagion by needle stick is likely to be much higher. In addition, during end-stage disease, virulent viral forms predominate, which may increase the risk to an even greater extent. Each of these variables must be assessed rapidly after an accidental high-risk needle stick. Antiretroviral therapy (ART) is effective at preventing HIV transmission via needle stick if given before viral RNA incorporates into the host genome as proviral DNA. This is thought to occur within about 48 hours, but under the best scenario, ART should be given within 1 hour of a needle stick. Circumstances are often murky, with key information such as viral load, viral resistance history, and even HIV serostatus of the patient variably available; therefore, urgent consultation with an HIV or occupational health specialist is imperative after a needle stick. (Hepatitis B and C transmission must also be considered.)