Variant forms of Trypanosoma rhodesiense [now Trypanosoma brucei rhodesiense]
This trypanosome is known to cause fast-onset sleeping sickness in Southern and Eastern Africa, and is found in many ungulate game animals. It’s also known to masquerade as other subspecies of Trypanosoma spp. when game reserves were tested for the parasite, and when blood smears are analyzed in patients with sleeping sickness. However, seeing the trypanosome form is enough to diagnose a patient (analyzing the subspecies is largely for distribution data), and though this subspecies is particularly virulent, the treatment is the same as for other subspecies.
Originally treated with a drug known as “Atoxyl” (developed by the great physician Paul Erlich), the arsenic-based compound was known to cause blindness, and was often ineffective after the second stage of the illness. Less toxic compounds were developed over the years, and in the 1960s, it was even thought we might eradicate the disease. However, as humans are not the only reservoir of the disease, this proved harder said than done.
Today, Eflornithine is used to treat cases of African sleeping sickness (and, apparently, facial hirsutism). Given the low rates of infection and the general lack of demand for the drug, the manufacturer Aventis halted production back in 1999. However, in 2001, Médecins Sans Frontières and the World Health Organization signed a contract with the company to manufacture and donate the drug on a long-term basis.
Cool side note: You know how there’s the gene in about a third of Sub-Saharan Africans that can “prevent” (or at least make survivable) most strains of malaria, yet causes sickle cell disease when a person has two copies of the gene? There’s a similar trait with sleeping sickness! The gene APOL1 has two different variants that can prevent acute sleeping sickness (the kind that kills you), but can cause kidney disease if two copies of the same variant are inherited.
[Annals of Tropical Medicine and Parasitology. Liverpool School of Tropical Medicine, edited by Ronald Ross, March 1912.]