After two years living in the forests of Congo, Maman Louise was ill.

"My eyes rolled around my head and I couldn't stop talking. Sometimes I started singing, and then I became aggressive," she says.

"I was really bad, even to my own children. I wanted to kill my own son. I threw things at him. I was savage. But I had no idea what I was doing."

Maman Louise had fled her home during the civil war and caught sleeping sickness while hiding in the bush.

Sleeping sickness, or Human African Trypanosomiasis, is a disease caused by a parasite carried by the tsetse fly. People can have it for years and suffer nothing worse than fever and headaches.

But once the parasite gets into the brain, their condition deteriorates and they become withdrawn and unresponsive or aggressive, deranged and hyperactive. It can be fatal.

'Resurrection drug'

The disease is curable with a drug nick-named the "resurrection drug" for its dramatic ability to bring back patients from the edge of death.

Now Maman Louise is the picture of health. She lives with her family in Nkayi, 200km west of the capital, Brazzaville and works in her fields.

The miracle is that even once sleeping sickness has made someone deranged, the effects can still be reversed.

There was a case where a villager was chained to the doors of the church because the community could find no other way of restraining him, and now he is able to work for a living.

In Congo, most cases of illness are attributed to sorcery, and sleeping sickness is no exception.

'Magical powers'

Maman Louise was believed to be possessed with an evil spirit. Her son Bruno wanted to take her to a witchdoctor, or fetisheur, to free her from the spell that he thought had been cast upon her.

"If she had died, we were ready to make war on her brothers. We had suspected her brothers for a long time," he says.

"We thought they were using their fetishes against us, and we knew that if they killed our mother then we would be next. We had to stop them, otherwise we would become their bush meat."

Even preventing the spread of the disease in Congo involves understanding witchcraft.

The tsetse flies can be caught in a trap made of mosquito netting, with a saucer of petrol inside - once the fly gets in, it cannot find the way out again and quickly drowns in the petrol.

"The fly traps have become sought after possessions because people believe they hold special magical powers," explains Ildevert Mboungou, a nurse working for Medecins Sans Frontieres (MSF) at Nkayi Hospital.

"The ability to kill flies in a trap has become a symbol of great authority. The dead flies are proof of victory over the evil spirits and the fly traps are treated as charms or fetishes that can influence the supernatural world."

Side-effects

Maman Louise was treated with a drug called Melarsoprol, an arsenic derivative that creates an excruciating burning sensation as it is injected into the arm. It is so strong that it is kept in glass vials because plastic ones melt.

She was a lucky survivor - the drug can have deadly side-effects. For 10% of patients, it causes convulsions, coma, paralysis or death.

Health staff know that while they are trying to help someone, they could well be sending them to their deaths.

Two years ago, 63 people from one village were being treated for sleeping sickness with Melarsoprol and 11 of them died.

Experiences like this persuaded MSF to try a ground-breaking new treatment called Eflornithine.

Eflornithine has none of the lethal side-effects of Melarsoprol. It is painless and effective.

Drug company Aventis has set up a $30m programme with the World Health Organisation and MSF to deliver Eflornithine for free.

Risk

Unfortunately for people living in tsetse fly areas, Congo's health ministry says it will go back to using Melarsoprol because it cannot afford Eflornithine, even though the country is the fourth-largest oil producer in sub-Saharan Africa.

The government says the intravenous solutions, catheters and syringes that it would have to buy in order to administer the drug are too expensive, at around $100 per patient.

In Congo's hospitals, patients have to pay for their own medicine, as well as bringing their own sheets, washing their own clothes and fetching their own water.

As nurse Ildevert Mboungou says: "There is a risk is that the situation will slip back into the state it was in before. It only takes one sick person to infect 100 other people. We must try to not let this happen again in Congo."

MSF is campaigning for more research and development into a cure for sleeping sickness that would be quick to administer.

"Eflornithine is complicated to administer, requiring 14 days of in-patient care, day and night nursing, and staff training," said Graciella Diap, MSF's Medical Coordinator for the Campaign for Access to Essential Medicines.

"We need an easy oral treatment for Human African Trypanosomiasis, otherwise the disease will never end. Because it is carried by flies, it will never be controlled without an effective new medicine."