A bite from a tsetse fly carrying a parasite can transmit sleeping sickness, a disease that without treatment can progress rapidly from mild symptoms to death. Now acoziborole, a new single‑dose medication, could help the World Health Organization reach its goal of eliminating the disease by 2030. A committee of the European Medicines Agency has given a significant green light to the drug, which could be used as early as next year.
Acoziborole is taken as three pills swallowed together in a single dose, replacing older treatments that required intravenous drugs that could cause severe vein pain and were fatal for about one in 20 patients. The current first‑line oral treatment, fexinidazole, must be taken for 10 days and can cause nausea, vomiting and heart‑rhythm disturbances. Clinical trials of acoziborole reported only one notable side effect: mild to moderate headache.
“For decades, available treatments were difficult to use,” says Dr. Gerardo Priotto, who leads WHO’s sleeping sickness efforts. Earlier therapies required staff, equipment and reliable infrastructure—resources often lacking in remote, rural areas where most cases occur. The simplicity and tolerability of acoziborole can greatly ease patient care, expand access to treatment and speed progress toward elimination, Priotto says.
Dr. Stéphane Hugonnet of the Drugs for Neglected Diseases Initiative (DNDi), who worked on the clinical trials, notes that harsh side effects of past medicines discouraged people from seeking care. DNDi developed acoziborole with Sanofi and partners including the Gates Foundation. DNDi began work in 2003 to address conditions that pharmaceutical companies had little financial incentive to pursue.
The tsetse fly picks up the Trypanosoma brucei gambiense parasite from infected people and transmits it to others. The insect thrives in warm savanna woodlands and vegetation along lakes and streams, so cases tend to concentrate in remote communities dependent on fishing, hunting and agriculture. “Like many tropical diseases, sleeping sickness is a disease of the poor,” says Dr. Peter Hotez of Baylor College of Medicine.
Sustained control efforts—tsetse fly control, diagnostics and treatment—have dramatically reduced deaths. Annual reported cases worldwide are about 1,000, with nearly two‑thirds in the Democratic Republic of Congo (DRC). But the disease has rebounded at times in history, Hotez warns.
Sleeping sickness progresses in two phases. The early stage causes fever and headaches; if the parasite crosses the blood‑brain barrier it triggers a later stage with neurological effects—confusion, convulsions and disruption of sleep–wake cycles that give the disease its name. Without treatment the illness can lead to coma and death. Acoziborole treats both stages.
Dr. Wilfried Mutombo Kalonji of DNDi calls the drug “transformative.” Kalonji, who oversaw clinical trials in South Ubangi province in the DRC, is now leading research to see whether serologic blood tests can be reliable enough to start treatment immediately in the field, instead of waiting for more complex confirmatory tests. If testing and treatment could occur the same day, more patients could be treated and human reservoirs eliminated, potentially ending transmission, says researcher Monica Mugnier of Johns Hopkins, who studies the disease.
Next steps include review of acoziborole by the DRC Ministry of Health and WHO to determine whether treatment guidelines should be updated, which would aid authorization in other countries. Experts caution that future cuts to U.S. and Western funding could hinder access in the countries that need the drug most.
Conducting clinical trials in remote African settings posed major challenges: no electricity or water, limited transport and the need to train health workers and provide internet and power for testing. “We had to set up all this,” Kalonji says. Despite difficult conditions, African researchers and the patients who participated made much of the progress possible.
Fran Kritz is a health policy reporter based in Washington, D.C., and a contributor to NPR.