Also known as human African trypanosomiasis (HAT), the disease disrupts the sleep cycle when parasites infect the brain.
Some 30 years ago the drug Eflornithine was introduced for treatment of the disease, which is spread through tsetse flies.
But patients in rural areas most at risk can rarely afford the drug, which is ineffective against more advanced forms of the disease, according to World Health Organization's (WHO) Department of Control of Neglected Tropical Diseases. “Despite some efforts and some promising candidates, no new drug has been added for HAT treatment,” WHO medical officer, Jose Ramon Franco, told IRIN.
The hard part has been to design a drug that kills the parasite without harming the brain, Franco told IRIN. An arsenic-based drug to attack parasites once they have infected the brain kills one in 20 patients.
Paul Wyatt, director of the drug discovery for tropical diseases programme at the Scotland-based University of Dundee, said scientists have discovered a new way to kill the parasite without harm to the patient.
“The first is identifying an Achilles heel of the parasite, such as an enzyme which is essential for the survival of the parasites, known as a drug target. The second is to confirm that molecules can disrupt these targets and so kill the parasite.” He said the university is now developing drugs that may be ready for testing on humans within 18 months.
WHO’s Franco told IRIN the ideal drug for HAT should be oral, low-toxicity, simple to use, easy to store, effective in both early and advanced stages and in forms of the disease found in West and Central Africa as well as East and southern Africa. And, “most important of all, be affordable,” he said.
Even if the drug makes it through trials there is still the issue of affordability, said Alan Fairlamb with the University of Dundee’s drug unit. “There is little economic incentive for big pharmaceutical companies to engage in diseases from sub-Saharan Africa. We’ve seen that these companies are now looking to Asia and Latin America as emerging markets, but one doesn’t exist in Africa yet.”
Drug manufacturers have started to produce vaccines for poor countries at reduced prices in exchange for donors guaranteeing orders over the long-term in “advance market commitments”.
WHO estimates that tens of thousands of people in sub-Saharan Africa are infected with HAT annually. But as diagnosis requires examining brain fluids through a lower-back puncture, patients with no access to health facilities may die without ever being diagnosed.