Page last updated at 01:31 GMT, Friday, 15 July 2005 02:31 UK

The disease that makes people zombies

Image of a boy with sleeping sickness
The parasitic infection causes a zombie-like state

The very name, sleeping sickness, may give the impression that it is an uncomplicated ailment, which passes after a while, much like a mild fever.

But in reality, the complete opposite is true, says Professor Sanjeev Krishna of St George's, University of London and the Wellcome Trust.

At the African hospital where he works in Lucala, about a 10-hour drive from the Angolan capital of Luanda, he see many patients with classic symptoms of the disease.

"At first it will cause headaches, aching muscles and maybe itching.

Nightmarish qualities

"But in the late stages, when the parasites have invaded the brain, the signs become more obvious and ominous.

"Victims find it hard to concentrate. They become irritable, their speech is slurred and they stop eating.

This is an infection that carries nightmarish qualities, reducing many of its victims to a zombie-like state
Professor Krishna

"Their daily rhythm becomes disrupted to such an extent that they can't sleep at night and find it almost impossible to stay awake during the day.

"It even becomes very hard for them to do simple mental tasks, such as drawing a straight line.

"This is an infection that carries nightmarish qualities, reducing many of its victims to a zombie-like state before they go into a coma and die.

"Those that do survive can be left with irreparable brain damage," he said.

In Uganda, every third person is at risk of getting sleeping sickness and in some regions it is a bigger killer than HIV/Aids, he said.

There are no vaccines, no preventative medicines and you can be re-infected - providing you survive the first bout.

Future hope

Sleeping sickness kills about 50,000 people worldwide, according to official records. But Professor Krishna said the real toll was probably much higher.

"At any one time, 60 million people are living under the threat of getting sleeping sickness, but only one in 20 of them will have access to even basic medical facilities."

He said tests used to diagnose and the drugs used treat the disease were decades old and lacking.

"Melarsoprol, which has been around for over half a century, contains arsenic and kills at least 5% of the patients who take it.

"It is so potentially lethal it would never be licensed today, yet we have little choice but to engage in this medical Russian roulette," he said.

The parasite that causes sleeping sickness, called Trypanosoma brucei and carried by tsetse flies, is also learning how to become resistant to the available drugs, making the discovery of new treatments a necessity, he said.

He is hopeful. "With this new sequencing breakthrough, investment and better surveillance and treatment I believe the disease can finally be put to sleep for good."


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