A genetic test targeted at cattle could have a substantial impact in controlling sleeping sickness in east Africa, conclude authors of a fast-track study in this week’s issue of THE LANCET.
Sleeping sickness caused by Trypanosoma brucei rhodesiense (transmitted by the tsetse fly) is fatal if not treated. Drug treatment can be associated with severe side-effects, and up to 5% of people die as a result of chemotherapy. Livestock—especially cattle—are a known reservoir of T b rhodesiense; they also carry the non-human-infective parasite Trypanosoma brucei brucei (T b brucei). The ability to detect the difference between these two parasites would therefore enable the estimation of potential infection risk for the surrounding human population.
Sue Welburn and colleagues from the University of Edinburgh, UK, tested 70 T brucei samples for expression of the serum-resistance-associated (SRA) gene, which allows T b rhodesiense to survive in human serum. SRA was present in all 29 samples from patients with sleeping sickness, and in all eight cattle samples that were resistant to human serum in vitro. The gene was not expressed in any of the 33 cattle samples that were susceptible to human serum.
Sue Welburn comments: “Detection of the SRA gene could provide the basis for a simple diagnostic test to enable targeted control of T b rhodesiense in the domestic livestock reservoir, thereby reducing the public-health burden of sleeping sickness in east Africa.”
Contact: Dr Sue Welburn, Centre for Tropical Veterinary Medicine, The University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian, EH25 9RG, Scotland; T) +44 (0)131 650 6228; M) +44 (0)7740 950863; E) sue.welburn@ed.ac.uk
Journal
The Lancet