What are the current treatments for sleeping sickness and their limitations?
Disease is caused by two subspecies of Trypanosoma brucei (T. b.) gambiense (g-HAT; 98% of reported sleeping sickness cases) and T. b. rhodesiense (r-HAT), and occurs in two stages: the early stage has non-specific symptoms and is often un- or misdiagnosed, and the late stage, where the parasite crosses the blood-brain barrier, causing serious neurological disorders including sleep cycle disruptions, paralysis, and progressive mental deterioration.
Without effective treatment, the disease usually leads to death. A lumbar puncture is needed to differentiate between stages in order to choose the appropriate treatment.
Current treatments are difficult to administer, and are stage-specific:
Treatment of stage 1 HAT
- Pentamidine (1940) for g-HAT and suramin (1920s) for r-HAT, require injections and are ineffective for stage 2.
Treatment of stage 2 HAT
- NECT – nifurtimox-eflornithine combination therapy (2009): for stage 2 g-HAT, requires 14 slow intravenous infusions of eflornithine of 2 hours each over 7 days, together with three times a day oral nifurtimox for 10 days. Requires specialized hospital administration and trained staff. Since its addition to the EML, NECT is first-line treatment for stage 2 g-HAT.
- Eflornithine (1981): today seldom used alone, requires an extended stay in hospital during administration (56 intravenous infusions – four times per day, over 14 days).
- Melarsoprol (1949): No longer used for g-HAT. Remains the only drug available for stage 2 r-HAT – a toxic arsenic derivative that causes pain and fatal encephalopathy in up to 5% of patients who receive it.