you'd think that that becoming a mathematician would guarantee you a quiet life - but don't put money on it. Catherine Comiskey has been in the business for nearly 20 years and her life is anything but quiet. It's also full of variety. "People don't realise what maths can lead to," says Comiskey, lecturer in mathematics and statistics at NUI Maynooth. "I've worked with the medical profession, the police, insurance companies, Aborigines and even social workers involved with drug users." The academic life is, she says, a great one. "You're doing something you love and you're paid to do it."

However, being female and an academic brings its own problems. "It's hard to find role models and mentors," she says. "In my discipline there's less opportunity to have friends of your own sex. It's not just her gender that isolates her. "There's nobody in Ireland doing what I'm doing, so I have to travel to get a perspective on my work and exchange ideas with peers." And while all that travel may sound great - it is work, not junkets, she stresses.

At school, Comiskey was good, rather than brilliant, at maths. "French was my best subject, but I loved maths and that's what has stood to me." Born in Dublin, Comiskey moved to New Ross, Co Wexford, with her family, in the 1970s. There, she attended the local Mercy Convent, but studied honours maths at the nearby Christian Brothers school.

She followed her brother to Trinity, where she studied maths and philosophy and then took a part-time teaching job at Waterford IT. She fell in love with teaching, but quickly realised she would never get a permanent job without a research degree. It was DCU's professor Alistair Wood who suggested a couple of research projects. In the event, Comiskey plumped for a medical project on measles epidemics. "I looked at how the numbers change with time and how vaccination affects the numbers. The key question was: What level of vaccination, and at what age, was required to eradicate the disease? It's maths that answers a question like that. It's based on differential calculus. I found that you needed 98 per cent coverage."

Following a stint setting up a statistics department for clinical trials at St James's Hospital, Dublin, Comiskey says she was "hungry again for research and study". It was the mid1980s and AIDS had emerged as a killer disease. "I decided to do a PhD on the transmission dynamics of HIV and its progression to AIDS in Ireland. I did surveys of intravenous drug users and looked at the spread of the disease through and from that group. I concluded that the promotion of needle exchange rather than safe sex was more effective within the drug users group. The sexual spread of HIV from drug users to non-drug-users was slower."

During her PhD years, Comiskey married her architect boyfriend, Peter Carroll, and found that her life suddenly changed. "It was the first time I realised the differences between male and female academics. I was going home to cook dinner and had to have all my work done early. The men could stay till 10 p.m. But that's what I wanted. I've always ensured that I have a life outside my work."

Her PhD complete, Comiskey's next move was to Australia, where she got a job at the Edith Cowan University, Perth, and worked on AIDS and meningitis research. It was the mid-1990s and Comiskey and her husband had bought a house with a swimming pool and had started a family. On maternity leave with her second child, she was invited to interview for a job in Tallaght IT. "I flew home with a 10-week-old baby, did the interview and got the job. It was a huge gamble because I had to pay my own expenses."

The environment at Tallaght, Comiskey says, was both progressive and encouraging. One of the highlights of her Tallaght years, which began in 1995, was a trip to an applied maths conference in Russia, where most of the audience was Russian - and female. It brought home to her how relatively few female mathematicians there are in Ireland.

Back at home, Comiskey was approached by the Health Research Board to do a study which would estimate the number of opiate users in Dublin. "There were no real figures. Each group - the Garda, the methadone treatment centres and hospital admissions - had their own lists. I worked with three sets of data and was able to eliminate duplications in them. My approaches and methods were laid down by the EU.

An international network of researchers had been set up to look at ways and methods of estimating the prevalence of drug use and I was invited to join them. I'm still a member."

Comiskey estimated that there were 6,500 known opiate users in Dublin in 1996. Using what's called the capture and recapture method, she estimated that the number of hidden opiate abusers was also around 6,500. "The figure of 13,000 seems high, but if you look at the ratio of known to unknown, you have a ratio of 1:1. Other European countries would have ratios of as much as 5:1."

Comiskey has continued her research into drug abuse and is currently working on 1998 data. Her involvement, too, in the monitoring of infectious diseases continues via her PhD students.

Comiskey joined the staff of NUI Maynooth in 1998. "I was in the school of science in Tallaght, but I'm in the maths department here. As a mathematician, it's better to be in a maths department and in a university setting you also get more time for research."

Her next trip is to a world harm-reduction conference in India in April, where she has been invited to make a presentation of her work. "When I was going to the Christian Brothers to study maths, I had no idea it would lead to to a career which involves travelling all over the world," she muses. "I'm on a couple of European expert groups and I'm learning all the time from other people. I benefit greatly from these meetings - the discussions and the sharing of ideas. For me, it's a vocation rather than a career. There's no let-up. Even while on maternity and parental leave I've been putting together research proposals and travelling to meet my research collaborators."

Factfile

Education:

1975-80; St Mary's Secondary School, New Ross, Co Wexford. 1980-84; TCD (Bachelors degree in maths and philosophy). 1985-92; DCU (MSc and PhD in maths and a year's post-doctoral).

Family:

married to Peter Carroll, an architect.

Children:

Sean (7), Shannon (6), and Julia (2).

Interests:

reading and travel.

Current reading:

Women, Work and Identity, by Elizabeth Pearl McKenna.

Most recent holiday:

Across California with three children in a motor home.

Her next trip is to a world harm reduction conference in India in April, where she has been invited to make a presentation of her work