Hi there,Thank you for your inquiry. From what we gather from the question, you were asking about the possibility of HIV transmission through your friend using his toothbrush in the event that some blood might have gotten on it, after you spit blood into the sink. From the information given, this scenario is determined to be No Risk (transmission of HIV is not possible in the given scenario).
The scenario above does not meet the three components of the transmission equation (see below). In order for transmission to occur, a number of requirements must be met.
HIV transmission requires the presence of HIV positive fluid (such as semen, vaginal fluid, pre-cum, rectal fluid, breastmilk, etc), coupled with a High, Low, or Negligible Risk activity, that provides the virus with direct access to the bloodstream.
Although it is unknown whether the blood is HIV positive. From the HIV Transmission Equation, HIV transmission requires HIV particles in a bodily fluid (e.g. semen, pre-cum, vaginal fluids, etc.) to have direct access to the bloodstream through a High, Low, or Negligible Risk activity.
In this case, there has been no direct access to the bloodstream through this activity that would warrant a risk of HIV transmission. In addition, had it been HIV positive blood on the toothbrush, one study on HIV transmission and saliva has indicated that "In saliva, inhibition of HIV may be partly due to several inhibitors of viruses that are present in the saliva" (1). With this knowledge, it appears as though there are certain mechanisms that the body produces which render HIV inactive in saliva, essentially making HIV transmission through saliva challenging. You also mention that you cleaned the toothbrush in mouthwash as well.
Recommendation: No need for an HIV test with the scenario provided, please refer to a healthcare professional for other health related questions.
AIDS Vancouver Helpline/Online, Sonali
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1. Why Is HIV Rarely Transmitted by Oral Secretions?