Sleeping Sickness Is Caused by a Parasite, Not a Virus or Bacterium

Human African trypanosomiasis (sleeping sickness) is caused by a parasitic protozoan of the genus Trypanosoma—specifically Trypanosoma brucei rhodesiense or T. b. gambiense. It is neither a viral nor a bacterial infection.

This distinction is clinically important because:

• Antibiotics (antibacterials) and antivirals are ineffective.
• Treatment requires antiprotozoal agents (e.g., pentamidine, suramin, melarsoprol, eflornithine, fexinidazole).
• Transmission is vector-borne (tsetse fly), not person-to-person via respiratory droplets or casual contact.

Understanding the parasitic nature of the disease guides appropriate diagnostic testing (microscopy of blood, lymph fluid, or CSF) and targeted therapy.