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MRC News - September 2004

Tackling the tsetse fly

An MRC unit has been chosen to host part of an international effort to decode the tsetse fly genome, and is challenging some prejudices about African science in the process.

The tsetse fly, with its extremely painful bite, is not merely a nuisance in Africa: it carries a parasite that enters the bloodstream of its victim, causing a terrible and fatal disease called sleeping sickness.

Judging by its name, sleeping sickness (or trypanosomiasis) doesn't sound too unpleasant. But even in the early stages of the disease patients have to contend with high fever, weakness and headache, joint pain, weight loss and itching; followed by cardiovascular, endocrine and kidney disorders.

If left untreated, the parasite invades the central nervous system: patients lose concentration and become indifferent to their environment. Oddly enough, they can also find it difficult to fall asleep at night. In advanced stages, the pa-tient may suffer seizures and display maniacal behaviour, alternating with excessive sleepiness. Finally, these patients will fall into a coma and die.

Unfortunately for Africa's people, this isn't a rare disease: an estimated 300 000 people are infected with sleep-ing sickness every year, most of whom are not diagnosed - let alone treated.

From 1906 to 1931, the treatment for sleeping sickness consisted of drugs based on arsenic, the danger of which became clear when around seven hundred patients died after receiving the wrong dose.

In response to the disaster, a Swiss chemist developed a treatment called Melarsoprol in the 1930s. It was a bold concept: a highly toxic arsenic-based molecule and its own antidote contained in a single product.

A full seventy years later, Melarsoprol is still the most effective way of treating sleeping sickness. But it is by no means safe - Melarsoprol kills around 10% of the people who take it.

And the bad news is that scientists aren't optimistic about safer, more effective treatments; they predict that better drugs to treat sleeping sickness are at least a decade away.

So the focus of scientific endeavour has shifted to its carrier: the tsetse fly. If the presence of the fly in Africa can be reduced, or the fly itself somehow be rendered harmless, scientists will have a real chance of saving the lives of millions of Africans.

To do this, however, requires a thorough understanding of the tsetse fly - both biologically and genetically. This is why the World Health Organisation (WHO) has decided that the genome of the tsetse fly must be decoded.

The good news for Africa is that, for the first time, African scientists will be able to take part in this process - and on African soil: the MRC/ UWC/ SANBI Bioinformatics Capacity Development Research Unit has been chosen to host the annotation and analysis of the ge-nome in Cape Town.

During annotation, the position and function of each gene is predicted using sophisticated computer methods.

"The advantage of doing the annota-tion in Africa is that we are in a position to test our results right here - to do experimental studies on the biology of the tsetse fly that will in turn help us identify important features of the genome," says Dr Winston Hide, research director of the unit.

"This is a triumph for African science and African scientists. In 2002, when the genome of the malaria mosquito was sequenced (another disease with a major impact on Africa) African research institutions were completely ignored. People tend to assume that Africa has no scientific expertise."

Although African labs don't have the equipment to do the actual sequencing of the genome (which involves decoding the chemical composition of the DNA into a sequence of digital information), Dr Hide says Africa has a solid network of laboratories and researchers who will be able to make sense of this data and apply it in the field. "We want to find the genes," he says.

Dr Hide expects that this project will bring many international researchers to Africa, who can then share their expertise and so build capacity in this critical area of research.

"We are not interested in ‘ parachute science', where international scientists arrive here, do research, and then leave again, taking all their expertise with them. This project can and must be used to build scientific infrastructure in Africa."

But Dr Hide and his team haven't been resting on their laurels: in prepara-tion for the tsetse fly project, the unit trained a group of fifteen students from all over the continent in pathogen ge-nomics earlier this year.

More good news is that the South African government is supporting these efforts: the Department of Science and Technology has committed R35 million over three years for the development and rollout of the National Bioinformatics Network, which has already trained forty South African students to a world-class level.

For Dr Hide, the tsetse fly project has wider implications than just the prevention of sleeping sickness. "Right now we're short of people that can do this particular type of analysis. We are desperately in need of the expertise that will come to Africa.

"The skills we will learn, and the people that will be trained, can be used to address our own problems in South Africa, and in particular, increase our capacity to deal with HIV/ AIDS."


     
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Last updated:
11 July, 2011
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