Tuberculosis is a disease we got rid of but is now on the way back. We need new drugs to treat it

Those which account for 90% of the burden of disease in Africa and an estimated 500,000 deaths each year. A host of tongue-tripping, often unpronounceable names: human African trypanosomiasis (sleeping sickness), filariasis (elephantiasis), onchocerciasis (river blindness) and schistosomiasis (bilharzia).

It's an irony not lost on Barrett, 48, when we meet in his office at Glasgow University. Specialising in neglected tropical diseases, the professor of biochemical parasitology is chair of a drug efficacy working group at the World Health Organisation (WHO) and a scientific advisor to the Scottish-based charity Developing World Health, lending expertise to their 50p Life Change Appeal which aims to raise £1 million to treat schoolchildren in Africa.

But back to the original question. "It was clear to me Glasgow was teeming with parasitologists, there is some fantastic research which goes on here," he says. "You have this incredible history going back to the late 19th century and early 20th century."

Barrett reaches for a hefty tome on a nearby shelf: Manson's Tropical Diseases. "Patrick Manson is often said to be the father of tropical medicine,'" he explains. "A distant relative of David Livingstone from Oldmeldrum, Aberdeenshire, even today his is considered the principal text. His big discovery was showing the worms which cause elephantiasis are transferred by mosquitos."

Barrett reels off a long list of eminent Scots pioneers to have worked in tropical medicine and parasitology, including Sir Ronald Ross who, under the tutelage of Manson, made the link between mosquitoes and the transmission of malaria parasites.

Scottish pathologist and microbiologist David Bruce first discovered human African trypanosomiasis, while William Leishman, an Army doctor and University of Glasgow alumni, led early studies into leishmaniasis, a disease spread by female sand fly bites invading the liver and spleen.

Then there's Glasgow-born Muriel Robertson who studied the role of tsetse flies in transmitting the African trypanosomes, the agents of sleeping sickness disease, and Kilmarnock's Robert Leiper who made significant discoveries about parasitic worms in conditions such as snail fever.

"Scotland had the Enlightenment philosophy and this whole population who wanted to learn," says Barrett. "Livingstone is the great example of the mill boy who paid his own way to go through university. He wasn't alone in that either: Manson was going to be a blacksmith but had a bad back and became a doctor instead.

"Bruce, Ross, Leishman, all of these individuals didn't come from the higher echelons of society: many were middle or lower middle class. They could study in Scotland at time when the universities were full of this culture of invention."

Some 250 years later, Barrett – an Essex boy of East London stock – finds his own path irrevocably intertwined with Glasgow academic life. While far too modest to place himself among the echelons of such lofty company, in modern-day science terms his contribution is arguably no less impressive.

He began his own career researching parasitic protozoa at the University of Cambridge in 1986. After two years working in France, followed by a stint at the London School of Hygiene and Tropical Medicine, he arrived at Glasgow University in 1996.

His role involves examining the biochemical workings of parasites with a view to designing new drugs for their control. He hopes to tackle the likes of fatal brain condition human African trypanosomiasis, chronic and disfiguring skin lesions of leishmaniasis and chagas disease, which attacks the cardiac system and is spread through parasitic "kissing bugs".

"The bad news is that, for a number of these diseases, resistance is spreading which is why we desperately need new drugs," says Barrett. "The drugs we do have are universally awful. One of the drugs for human African trypanosomiasis is based on arsenic.

"With chagas disease both of the drugs currently used are carcinogenic. Leishmaniasis, meanwhile, has a drug based on antimony, a heavy metal alchemists are more famous for using than pharmaceutical chemists. One in 20 people given that particular drug suffer heart failure. So, in short, all the drugs are rubbish and resistance is spreading. Millions are affected with these diseases, but it's the world's poorest people so their plight goes largely unheard. For many years we thought of the pharmaceutical industry, 'How inhumane.'"

But then a watershed happened at the turn of the 21st century. Barrett recounts the story of a drug called eflornithine, developed to treat human African trypanosomiasis. "During the mid to late-1990s, the WHO couldn't get anyone to make it as it is expensive to produce," he says. "It had first been proposed as an anti-cancer drug but was then discovered to prevent hair growth.

"Suddenly you had a situation where there is a compound WHO couldn't get anyone to make to save lives because there was no possible financial return for investment, yet it could be made and marketed at preventing unwanted facial hair growth in American and European women.

"No-one on the planet could deny there is something wrong with this system. Even the pharmaceutical companies would agree but, at the end of the day, they are businesses not charities. That's not because they are bad guys: it's the practical reality."

In this case WHO deftly persuaded the pharmaceutical companies to produce the drug afresh for free and to be distributed across Africa – a project ongoing for the past 12 years. "By 2000, WHO estimated 300,000 people were affected by human African trypanosomiasis," says Barrett. "The most recent figures, for 2011, however, suggest that number has fallen to about 7000. We have always known it was a controllable disease but it was about having the drugs available to do it."

It is stories like this which give him hope and cement his faith in a path that was first cemented during an undergraduate zoology trip to Tanzania in 1985. "Seeing the extraordinary poverty many people were obliged to live in. Things like malaria, leprosy and other diseases which were all part of everyday life," he says. "For the most part, here in the UK, potentially fatal infectious diseases aren't an everyday part of our lives. It seemed to me a situation with such controllable things, but yet we weren't controlling them. That's when I became interested in seeing how drugs could be used against parasites."

While his line of work may seem a constant uphill battle, Barrett is certainly a realist: something evident as he talks about his childhood growing up in Harlow, Essex. "I went to a comprehensive school and there was a lot of pressure not to be academic," he says. "Even so, my parents were idealistic which I think may have had a bearing on why I'm so interested in diseases of poverty. If you go there today Harlow is a pretty rough place but it was built with these fantastic ideals, a bit like East Kilbride and other new towns.

"There is this great Henry Moore sculpture that was the town symbol showing a family group of a mother, a father and a baby. Every Friday night people would pour out of pubs and this sculpture would wake up on Saturday morning with a series of genitalia, swastikas and facial hair painted all over it to the extent that Moore wanted it moved. The sculpture is now behind glass in the town hall."

Some 400 miles north, home is now Milngavie, East Dunbartonshire, where Barrett lives with wife Sophie, 42, a consultant at Glasgow's Beatson Oncology Centre, and their two sons Tom, 12, and Angus, 11. His affinity to this corner of the world, he admits, could be in part down to a Scottish grandfather who originally hailed from the remote island of Eilean nan Ron off Sutherland.

While acknowledging his work may appear to lack relevance to the average man or woman on the street, Barrett is a robust advocate of what he describes as "Scotland's incredible history of interactions with Africa" and enduring presence as a hub for "the world's best parasitologists".

"Practical benefits, aside from the philanthropic, is that we can make drugs which, because they are biologically active against a certain set of bugs, there is always the chance a similar set of compounds might be active against diseases which do affect us here," he says. "For example, a close relative of the compound that didn't make it for trypanosomiasis is now being tested for another parasitic disease called cryptosporidiosis. That is a disease of both humans and animals in Scotland for which there aren't currently any drugs.

"Take something like tuberculosis, a disease we thought we had got rid off, but is now on the way back and in a form which is resistant to many of the drugs used against it for the last 40 years. You always need new drugs to treat those diseases." And it's here, amid the decidedly non-tropical climes of Scotland, he believes that vital key could finally be unlocked.

Prof Mike Barrett will give an address at the David Livingstone and The Scottish Encounter with Tropical Disease Symposium 2013 on February 25. Visit www.gla.ac.uk. Developing World Health, visit www.50pence.org.

Mike Barrett

Professor of biochemical parasitology