Hi, Welcome to HCM, i am Dr. Das
There is a test for p24 protein which can be done arter 15 days of exposure. If it is negative it is rare to get infection. But you have to confirm it after 3 month and 6 month.
After 3 month if the Elisa
test report is negative then also you can get confirm using DNA PCR technique.
But it would very much easy if you had the recent HIV
report of the stranger.