A fifth case of measles in as many weeks has raised concerns about what could happen if the outbreak spreads beyond university grounds.

University of Queensland infectious diseases management expert Dr Simon Reid said controlling such a highly infectious disease in such a dense population centre was difficult, with hundreds of students potentially exposed in a single lecture.

The measles virus seen under a microscope.

Queensland Health on Thursday confirmed a fifth case of measles in a student based at UQ's St Lucia campus, just a day after the fourth case was revealed.

Dr Reid said it was impossible to predict what would happen next but it would depend on vaccination rates within the campus and any other areas exposed to the disease.