In the last decade, the prevalence of Trypanosoma brucei gambiense human African trypanosomiasis (HAT) has fallen and HAT has been targeted for elimination. Development of safe and efficacious drugs for HAT, applicable in an elimination context, is considered as a high priority. The drug developmental process is however slowed down by the need to follow-up treated patients for 18 months to decide on cure. For timely diagnosis of treatment failure in clinical trials, patients should have control visits with follow-up examinations at 6, 12 and 18 months after treatment. Furthermore, due to repeated lumbar punctures, treated patients refrain to present for control visits spontaneously, and tend not to comply with follow-up. Clinical trials on new drugs for HAT would therefore be accelerated by availability of an early test of cure. Trypanosomal spliced leader (SL)-RNA and neopterin are good candidates for accurate and shortened treatment follow-up. In particular SL-RNA detection in blood offers an opportunity for non-invasive post-treatment follow-up The objective of the DiTECT-HAT-WP4 study is to validate the diagnostic performance of cerebrospinal fluid neopterin quantification and of blood and cerebrospinal fluid trypanosomal spliced leader RNA detection for assessing treatment outcome. The DiTECT-HAT-WP4 study is embedded into an ongoing therapeutic phase II/III study (DNDi-OXA-02-HAT) testing a new oral single dose drug against HAT. Within the Framework of the therapeutical trial, patients will have post-treatment examinations, including blood and cerebrospinal fluid examination at day 11, and during follow-up at month 6, month 12 and month 18. Combination of DiTECT-HAT-WP4 with this ongoing clinical trial allows evaluation of new treatment outcome assessment markers during follow-up without the need for additional lumbar or venipunctures. The volumes of venous blood and cerebrospinal fluid taken will be increased by 2.5 mls for the DiTECT-HAT-WP4 study.