Introduction Human African trypanosomiasis (HAT) is caused by Trypanosoma brucei gambiense and rhodesiense and is transmitted to humans by tsetse flies in sub-Saharan Africa. To detect cure or treatment failure, patients are followed up after treatment integrating the use of biomarkers in blood or cerebrospinal fluid (CSF).

Methods A systematic review of the literature according to the PRISMA Statement for Reporting Systematic Reviews was done, focusing on biological markers for HAT post-treatment follow-up. Articles were retrieved from PubMed (https://www.ncbi.nlm.nih.gov/pubmed/) by using keywords: Human African Trypanosomiasis, Biomarkers, Follow up, Post treatment.

Results A panel of biomarkers is used to detect relapses or to confirm recovery. For post-treatment follow-up, an examination of the CSF is performed. White blood cell counts in CSF with a defined cut-off value have been proven to be the most accurate to assess the treatment outcome. The intrathecal immunoglobulin M synthesis is a specific and sensitive parameter for the detection of CNS involvement in cases of HAT caused by T. brucei gambiense. The decrease of trypanosome-specific antibodies concentrations in CSF could be a good parameter for definite cure. High CSF IL-10 levels during treatment follow-up indicate recurring CNS inflammation and treatment failure. An increase of Neopterin in CSF and the presence of trypanosome spliced leader RNA in the blood have a high potential as predictors for treatment failure but need further validation.

Conclusion New biomarkers for post-treatment follow-up in HAT should 1) have high diagnostic specificity and sensitivity; 2) be applicable in field conditions; 3) preferentially be performed on blood and thus avoid the painful lumbar puncture during post-treatment control visits; and 4) shorten the follow-up period.