What Causes Blisters On The Penis?

i have blisters lined up in the rim of my shaft of penis i mean base of the head of penis i m virgin and i am 16 years old plz help wat it can be?? i am worried help me....i j wanted 2 ask that if i kill a mosquitoe with naked hands who has bitten earlier an hiv positive person or any other std suffering person and i touch my penis with those hands or mucous membrane with those hands can i be infected plz help