'If the smallpox virus were released in a crowded airport, there is a very real possibility that it would spread globally. Recently, I was involved with the Pan American Health Organisation looking into the threat of bio-terrorism.
'My role is to make sure the smallpox vaccines are safe and effective, wherever they are used in the world. Diseases don't respect national borders. As a microbiologist at the World Health Organisation, I'm responsible for the quality and safety of all biological medicines ("biologicals") including polio and meningitis vaccines.
'My team of 12 in Geneva works closely with the top biologicals specialists world-wide - just 50 people - developing and establishing international guidelines for vaccines, blood products and cutting-edge gene therapy products.
'At the moment the big push is to find ways to eradicate malaria, TB and HIV, and to achieve global agreement on what needs to be done in gene therapy clinical trials to ensure the health of the whole human population is not damaged.
'Science is about the thrill of discovering what's new and understanding nature. Working for an international organisation, such as the WHO, gives you the opportunity to work with great minds from all over the world. Science is hard work, but it has tremendous rewards at the end of the day. I find it fascinating.'
'All biologicals are either extracted from biological material like blood, made by bacteria, or grown in culture from human and animal cells. Sometimes biologicals consist of the live organisms themselves. The trick is to keep the biologicals safe yet effective. This is key whether they are vaccines, blood products, or gene therapy products.
'The WHO doesn't develop biological medicines. Its role is to write recommendations, after international consultation with specialists, detailing how biologicals should be made, with benchmarks for quality and safety. The WHO's recommendations aren't legally binding, but they're very influential, becoming the international standard as countries adopt them or use the guidelines as the basis for their own regulations.
'As well as these written standards, WHO sets the physical standards that scifiles use for measuring the activity of biologicals. For instance, WHO labs in London and Amsterdam distribute vials of biological medicines to individual countries so that their national standard can be calibrated against the WHO standard. This then forms the basis for clinical dosing or the specification for a vaccine. WHO cannot dictate; all countries are part of the standard-setting process.'
What language do you work in?
'Mainly English, the language of medicine and science. I also work in French and occasionally Spanish. Being Welsh I'm aware that a direct translation might not mean exactly what you'd expect - we have to be very careful translating WHO documents.'
Under the Microscope:
What disease would you like to eradicate?
'HIV. Other diseases are huge killers too, measles for instance, but HIV knocks out the breadwinners, so its eradication would have an enormous impact on society in Africa and India.'
What scientific discovery would you save from a burning building?
'The telephone, it's changed the world completely.'
WHO Internships offer students in health-related programmes a six-week to three-month opportunity to participate in the organisation's work
For details about applying to university, vacation work and careers in microbiology, contact The Society for General Microbiology
The Biochemical Society has information on university open days, summer studentships and careers in biochemistry
The BBC cannot accept responsibility for the content of external sites.