Fourth case of measles at Perth school

A fourth child has been diagnosed with measles at Perth Waldorf School, more than a week after the health department gave an on-site vaccine to students.

A Health Department spokeswoman confirmed the latest case, which comes three weeks after the highly contagious disease was first detected in an unvaccinated year 10 student who had returned from Italy.

Revelations that about half the school's 400 students were unvaccinated against the disease led the Health Department to offer a voluntary, free on-site vaccine to students, but it is unknown how many took up the offer.