She died in the intensive care unit of University Hospital, Cardiff, early yesterday morning after being taken ill on Friday evening in the same student hall of residence where other cases of the illness have occurred.
A university spokesman said that relatives of the latest victim were still being informed of the tragedy last night.
A programme of inoculations for up to 800 other students was brought forward by 24 hours as fears rose of further cases. On Thursday, a 19-year-old woman law student living in the same student block, University Hall, died within hours of being taken ill.
Three other students living at University Hall have the disease and are being treated at the hospital. Doctors said yesterday that two were making "good progress" on an isolation ward while the other, a 20-year-old male student, remains in intensive care, "seriously ill but stable".
Experts in communicable diseases believe the five students, who were not part of a close circle of friends, were affected by a "Group C" meningococcal strain of the disease which can kill within hours unless treated.
Meningitis cannot be passed on through normal social contact but weekend parties and discos were cancelled and the students' bar closed as a precaution against spreading infection.
Students living at University Hall have already been given a course of antibiotics but will now be vaccinated to give them further protection. Vaccination gives longer-term protection against meningitis although the jab takes 10 days before becoming fully effective.
Dr Bill Smith, director of public health for the Bro Taf Authority, said it was essential students remained on site in Cardiff to be vaccinated and that this would not increase the possibility of further infections. "All that should be done is being done. I hope that we have seen the worst of this," he said.
The university is anxious that around 100 students who went away for the weekend to visit parents or friends are contacted and vaccinated.
Professor Brian Smith, the university vice-chancellor, said: "Nothing is of more importance to the university than the safety and well-being of its students. Our hearts go out to the parents." He paid tribute to the maturity and calmness of students at the residence and of their parents.
Medical experts are stressing that friends, family and acquaintances of those living at University Hall are not at any special risk and do not need antibiotics.
Initial investigations suggest that the infection may be focused on a particular part of the residence.
Student welfare officers and counsellors from the Meningitis Trust charity spent yesterday helping undergraduates who were stunned by the latest death. Dot Hodge, president of the students' union, said: " It has been traumatic. Most students of this age are just not accustomed to dealing with this sort of grief. Our priority is to do everything we can to help them cope with this".
Leanna Jones, 19, an accountancy student, said she felt much safer after the antibiotics course.
"I was frightened at first because I didn't know what to do. But now I have had medication and have been told about the dangers I feel far happier" she said.
Dr Smith, for the Bro Taf Health Authority, stressed there was no need to panic. "Instead of being scattered to the four corners of Britain, it is much better that students who are absent return to Cardiff to get their vaccination."
An emergency hotline, with 10 extensions, was set up by the students' union. Student wardens are also making regular checks on the health of residents at University Hall.
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