title: Evaluation of rK39 rapid diagnostic tests for canine visceral leishmaniasis: longitudinal study and meta-analysis.
abstract: BACKGROUND
  There is a need for sensitive and specific rapid diagnostic tests (RDT) for canine visceral leishmaniasis. The aims of this study were to evaluate the diagnostic performance of immunochromatographic dipstick RDTs using rK39 antigen for canine visceral leishmaniasis by (i) investigating the sensitivity of RDTs to detect infection, disease and infectiousness in a longitudinal cohort study of natural infection in Brazil, and (ii) using meta-analysis to estimate the sensitivity and specificity of RDTs from published studies.
  
  
  METHODS
  We used a rK39 RDT (Kalazar Detect Canine Rapid Test; Inbios) to test sera collected from 54 sentinel dogs exposed to natural infection in an endemic area of Brazil. Dogs were sampled bimonthly for up to 27 months, and rK39 results compared to those of crude antigen ELISA, PCR, clinical status and infectiousness to sandflies. We then searched MEDLINE and Web of Knowledge (1993-2011) for original studies evaluating the performance of rK39 RDTs in dogs. Meta-analysis of sensitivity and specificity was performed using bivariate mixed effects models.
  
  
  RESULTS
  The sensitivity of the rK39 RDT in Brazil to detect infection, disease and infectiousness was 46%, 77% and 78% respectively. Sensitivity increased with time since infection, antibody titre, parasite load, clinical score and infectiousness. Sixteen studies met the inclusion criteria for meta-analysis. The combined sensitivity of rK39 RDTs was 86.7% (95% CI: 76.9-92.8%) to detect clinical disease and 59.3% (37.9-77.6%) to detect infection. Combined specificity was 98.7% (89.5-99.9%). Both sensitivity and specificity varied considerably between studies.
  
  
  CONCLUSIONS
  The diagnostic performance of rK39 RDTs is reasonable for confirmation of infection in suspected clinical cases, but the sensitivity to detect infected dogs is too low for large-scale epidemiological studies and operational control programmes.
authors: School of Biology, University of Leeds, Leeds, United Kingdom. r.j.quinnell@leeds.ac.uk
authors: Rupert J
authors: RJ
authors: Quinnell
authors: Connor
authors: C
authors: Carson
authors: Richard
authors: R
authors: Reithinger
authors: Lourdes M
authors: LM
authors: Garcez
authors: Orin
authors: O
authors: Courtenay
mesh_terms: D000818:Animals; D001938:Brazil; D002846:Chromatography, Affinity; D015331:Cohort Studies; D003955:Diagnostic Tests, Routine / Q000379:methods*; D004283:Dog Diseases / Q000175:diagnosis* / Q000469:parasitology*; D004285:Dogs; D007898:Leishmaniasis, Visceral / Q000175:diagnosis / Q000469:parasitology / Q000662:veterinary*; D008137:Longitudinal Studies; D010274:Parasitology / Q000379:methods*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014730:Veterinary Medicine / Q000379:methods*