Genetic Diversity and Population Structure of Trypanosoma brucei in Uganda: Implications for the Epidemiology of Sleeping Sickness and Nagana
Loading...
Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
PLoS neglected tropical diseases
Abstract
While Human African Trypanosomiasis (HAT) is in decline on the continent of Africa, the
disease still remains a major health problem in Uganda. There are recurrent sporadic outbreaks
in the traditionally endemic areas in south-east Uganda, and continued spread to
new unaffected areas in central Uganda. We evaluated the evolutionary dynamics underpinning
the origin of new foci and the impact of host species on parasite genetic diversity in
Uganda. We genotyped 269 Trypanosoma brucei isolates collected from different regions
in Uganda and southwestern Kenya at 17 microsatellite loci, and checked for the presence
of the SRA gene that confers human infectivity to T. b. rhodesiense.
Results
Both Bayesian clustering methods and Discriminant Analysis of Principal Components partition
Trypanosoma brucei isolates obtained from Uganda and southwestern Kenya into
three distinct genetic clusters. Clusters 1 and 3 include isolates from central and southern
Uganda, while cluster 2 contains mostly isolates from southwestern Kenya. These three
clusters are not sorted by subspecies designation (T. b. brucei vs T. b. rhodesiense), host
or date of collection. The analyses also show evidence of genetic admixture among the
three genetic clusters and long-range dispersal, suggesting recent and possibly on-going
gene flow between them. Conclusions
Our results show that the expansion of the disease to the new foci in central Uganda occurred
from the northward spread of T. b. rhodesiense (Tbr). They also confirm the emergence
of the human infective strains (Tbr) from non-infective T. b. brucei (Tbb) strains of
different genetic backgrounds, and the importance of cattle as Tbr reservoir, as confounders
that shape the epidemiology of sleeping sickness in the region.
Description
Keywords
Genetic Diversity, Population Structure, Trypanosoma brucei, Uganda, Epidemiology, Sleeping Sickness, Nagana
Citation
Echodu R, Sistrom M, Bateta R, Murilla G, Okedi L, Aksoy S, et al. (2015) Genetic Diversity and Population Structure of Trypanosoma brucei in Uganda: Implications for the Epidemiology of Sleeping Sickness and Nagana. PLoS Negl Trop Dis 9(2): e0003353. doi:10.1371/journal.pntd.0003353