Please help, how much of an increased chance do nurses have of contracting hiv/aids?

Hard to say: The increased risk come from an actual needlestick from an infected needle or a splash of blood into the eyes, for example. However, this doesn't necessarily happen that often. In addition, if the nurse had an occupational exposure such as what i've described above, they can opt to take anti HIV medications, which would also likely decrease the risk of HIV transmission if given relatively soon.