African sleeping sickness is almost a joke in the West. Films depict explorers being bitten by the tsetse fly and then falling into a slumber. But sleeping sickness, or Human African trypanosomiasis, is no joke to the hundreds of thousands of people it affects annually.
Dr. Gerardo Priotto explains that when the tsetse fly bites, it transmits a parasite into the blood, which, if left untreated, eventually makes its way to the brain.
"And when this happens, there are a series of neurological signs and symptoms that progress, and they show this sleepiness that gives the name to sleeping sickness," he explains.
"But also it will progress into severe mental confusion and coma and death, and it will eventually kill all of the persons that are infected by the parasite."
No financial incentive to develop safer treatments
Priotto works at Epicentre, a research group in Paris funded by the humanitarian organization Medecins Sans Frontieres or MSF.
MSF doctors have been fighting African trypanosomiasis in Africa for several decades, usually in some of the poorest, most rural areas, often places torn by conflict, such as the Congo. But because most sleeping sickness victims are poor, there's been no incentive for drug companies to develop new treatments.
"So, for a long time, for actually for 60 years, we have been using mainly one molecule that's called melarsoprol, and this drug is very toxic, extremely toxic to the point of killing the patient," Priotto says.
"And so this has been the first line treatment for 60 years, and the only alternative is another drug called eflornithine that is less toxic, but is very expensive and very complicated to administer."
People in places where eflonithine is used call it the "Lazarus drug," because the effects are so dramatic. But it requires intravenous infusion, four times a day, for 14 days. This intensity of materials and time are, unfortunately, resources not available in many poor areas.
Priotto and others thought that another drug, nifurtimox, might be effective in treating African trypanosomiasis in combination with eflornithine. Nifurtimox is used in South America to treat a similar disease. But the idea needed to be tested.
"We cannot do this study in nice hospitals that have research capacity; we have to organize the study right there where the patients are," he explains.
"So many times, this meant a lot of travel with difficult means, for example taking airplane, followed by a pirogue down the river, or sometimes in the back of a motorcycle, in very difficult conditions and for a very long time. And in the same way we needed to go, the investigators ourselves, but also to bring to that place all of the laboratory equipment, the reagents, the drugs, and all of the other equipment needed to do the study."
An extraordinary study yields extraordinary results
To study fewer than 300 patients took more than five years, employing dozens of collaborators in four rural study sites, thousands of kilometers apart in both Congo and the Democratic Republic of Congo.
"We had fabulous results, actually… and what we found in the analysis is that the combination that we were studying, nifortomix plus eflornithine, we have a 98 percent of cure rate, which is actually very high," he says.
"And in the control arm, which was the standard treatment of eflornithine, we had 92 or 93 percent cure rate. "
The treatment was also shown to be far less toxic, and the drug combination requires only 14 infusions of eflonithine, rather than 56, over only a week. Finally, the approach was far less expensive, both in terms of drugs and human resources.
Almost immediately, the World Health Organization recognized this drug regimen as the preferred treatment for African trypanosomiasis. The Central African Republic has already changed its national treatment protocol and several other countries are in the process of doing the same.
Priotto's work is published in The Lancet.