title: A systematic review and meta-analysis of trypanosome prevalence in tsetse flies.
abstract: BACKGROUND
  The optimisation of trypanosomosis control programs warrants a good knowledge of the main vector of animal and human trypanosomes in sub-Saharan Africa, the tsetse fly. An important aspect of the tsetse fly population is its trypanosome infection prevalence, as it determines the intensity of the transmission of the parasite by the vector. We therefore conducted a systematic review of published studies documenting trypanosome infection prevalence from field surveys or from laboratory experiments under controlled conditions. Publications were screened in the Web of Science, PubMed and Google Scholar databases. Using the four-stage (identification, screening, eligibility and inclusion) process in the PRISMA statement the initial screened total of 605 studies were reduced to 72 studies. The microscopic examination of dissected flies (dissection method) remains the most used method to detect trypanosomes and thus constituted the main focus of this analysis. Meta-regression was performed to identify factors responsible for high trypanosome prevalence in the vectors and a random effects meta-analysis was used to report the sensitivity of molecular and serological tests using the dissection method as gold standard.
  
  
  RESULTS
  The overall pooled prevalence was 10.3% (95% confidence interval [CI] = 8.1%, 12.4%) and 31.0% (95% CI = 20.0%, 42.0%) for the field survey and laboratory experiment data respectively. The country and the year of publication were found to be significantly factors associated with the prevalence of trypanosome infection in tsetse flies. The alternative diagnostic tools applied to dissection positive samples were characterised by low sensitivity, and no information on the specificity was available at all.
  
  
  CONCLUSIONS
  Both temporal and spatial variation in trypanosome infection prevalence of field collected tsetse flies exists, but further investigation on real risk factors is needed how this variation can be explained. Improving the sensitivity and determining the specificity of these alternative diagnostic tools should be a priority and will allow to estimate the prevalence of trypanosome infection in tsetse flies in high-throughput.
authors.affiliation: Department of Clinical studies, College of Veterinary Medicine and Agriculture, Addis Ababa University, Bishoftu, Oromia, Ethiopia. retaduguma@gmail.com.|Department of Animal Science, Institute of Agriculture, University of Tennessee, 2506 River Drive, Knoxville, USA. retaduguma@gmail.com.
authors.forename: Reta D
authors.initials: RD
authors.lastname: Abdi
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Food Animal Environmental Systems Research Unit, Bowling Green, Kentucky, USA.
authors.forename: Getahun E
authors.initials: GE
authors.lastname: Agga
authors.affiliation: Werer Agricultural Research Center, Ethiopian Institute of Agricultural Research, Afar, Ethiopia.
authors.forename: Weldegebrial G
authors.initials: WG
authors.lastname: Aregawi
authors.affiliation: Department of Clinical studies, College of Veterinary Medicine and Agriculture, Addis Ababa University, Bishoftu, Oromia, Ethiopia.
authors.forename: Merga
authors.initials: M
authors.lastname: Bekana
authors.affiliation: Department of Crop Protection, Faculty of Bioscience Engineering, Gent University, Ghent, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Van Leeuwen
authors.affiliation: Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Vincent
authors.initials: V
authors.lastname: Delespaux
authors.affiliation: Department of Comparative Physiology and Biometrics, Faculty of Veterinary Sciences, Gent University, Ghent, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Duchateau
mesh_terms: D000818:Animals; D007303:Insect Vectors / Q000469:parasitology*; D015995:Prevalence; D014345:Trypanosoma / Q000502:physiology*; D014370:Tsetse Flies / Q000469:parasitology*
keywords: Diagnostic methods; Glossina; Meta-regression; Systematic review; Trypanosome infection prevalence