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Title: Detection and control of T. brucei s.l. in the historic sleeping sickness foci of NW Uganda
Author: Cunningham, Lucas J.
ISNI:       0000 0004 6495 8103
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2017
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Gambian human African trypanosomiasis (gHAT) is a deadly disease caused by Trypanosoma brucei gambiense transmitted by tsetse flies (Glossina) and is found only in West and Central Africa. The NW of Uganda has been known as a focus of gHAT since the early 20th Century but the number of new cases has reduced from 948 in 2000 to 4 in 2015. NW Uganda is therefore a good testing ground for alternative control and surveillance strategies that could be employed at other foci in the drive towards elimination. Focussing on the Koboko foci of gHAT in NW Uganda, this study aimed to: (i) assess the prevalence of T. b. gambiense in the vector and potential reservoir host animals (cattle and pigs), (ii) develop a system for xenomonitoring gHAT and (iii) assess the impact of Tiny-Targets, a novel vector control technology, on the transmission of salivarian trypanosomes amongst local cattle. The tsetse population was sampled continuously from April 2013-July 2014 using pyramidal traps (four traps operated on average 18 days/month). A total number of 12,532 G. f. fuscipes were captured. A subset of these tsetse (6,664) were analysed for the presence of trypanosomes using either microscopy and/or molecular methods. No tsetse tested were found to be positive for T. b. gambiense but T. brucei s.l. (2%), T. vivax (3%) and T. congolense (4%) were detected. PCR-based analyses of bloodfed tsetse (131) showed that the predominant hosts were humans (37%), cattle (39%) and Monitor lizards (15%). A xenomonitoring system based on commercially available loop-mediated isothermal amplification (LAMP) kits were tested for their suitability to detect T. brucei s.l. DNA in tsetse. The study demonstrated that the LAMP kits were highly sensitive, being able to detect the equivalent of 0.1 trypanosome/mL. They could also detect T. brucei s.l. DNA in tsetse midguts six days-post ingestion. Analyses of 2,877 cattle from areas where Tiny Targets were present or absent using microscopy and PCR-based methods found that the targets had no significant impact on trypanosome prevalence; prevalence of Trypanosoma spp in cattle from areas with or without targets was 10% for both sites. T. b. gambiense was not detected unequivocally in cattle or pigs. This study showed that in a setting where gHAT is close to elimination it is extremely difficuIt to detect the parasite in the vector population. It also indicates that local cattle and pigs are not likely to be playing a role as reservoir hosts. The commercially available LAMP kits offer the basis of a novel and more cost-effective system for monitoring T. brucei parasites in low-prevalence settings.
Supervisor: Torr, S. J. ; Donnelly, M. J. ; Haines, L. R. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral