title: Multi-centre evaluation of repeatability and reproducibility of the direct agglutination test for visceral leishmaniasis.
abstract: OBJECTIVE
  To evaluate the repeatability and reproducibility of the serological direct agglutination test (DAT) for visceral leishmaniasis (VL) with aqueous antigen in a multi-centre study in VL-endemic areas in Sudan, Kenya and Nepal.
  
  
  METHODS
  Repeatability within each centre and reproducibility between the centres' results and an external reference laboratory (Belgium) was assessed on 1596 triplicate plain blood samples collected on filter paper.
  
  
  RESULTS
  High kappa values (range 0.86-0.97) indicated excellent DAT repeatability within the centres. The means of the titre differences between the reference laboratory and the centres in Sudan, Kenya and Nepal (2.3, 2.4 and 1.1, respectively, all significantly different from 0) showed weak reproducibility across centres. 95% of the titre differences between the reference laboratory and the respective centres were accounted for by large intervals: 0.6-9 fold titre variation for Sudan, 0.7-8 fold for Kenya and 0.26-4 fold for Nepal.
  
  
  CONCLUSIONS
  High repeatability of DAT confirms its potential, but reproducibility problems remain an obstacle to its routine use in the field. Reproducibility was hindered by alteration of the antigen through temperature and shaking, especially in Kenya and Sudan, and by nonstandardization of the test reading. DAT handling procedures and antigen quality must be carefully standardized and monitored when introducing this test into routine practice.
authors: Department of Public Health, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium. boelaert@itg.be
authors: M
authors: M
authors: Boelaert
authors: S
authors: S
authors: El Safi
authors: H
authors: H
authors: Mousa
authors: J
authors: J
authors: Githure
authors: P
authors: P
authors: Mbati
authors: V l
authors: Vl
authors: Gurubacharya
authors: J
authors: J
authors: Shrestha
authors: D
authors: D
authors: Jacquet
authors: A
authors: A
authors: De Muynck
authors: D
authors: D
authors: Le Ray
authors: P
authors: P
authors: Van der Stuyft
mesh_terms: D000372:Agglutination Tests / Q000379:methods* / Q000592:standards; D015982:Bias; D016022:Case-Control Studies; D019353:Endemic Diseases / Q000706:statistics & numerical data; D006801:Humans; D007630:Kenya / Q000453:epidemiology; D007898:Leishmaniasis, Visceral / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D009390:Nepal / Q000453:epidemiology; D011933:Reagent Kits, Diagnostic / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013397:Sudan / Q000453:epidemiology; D013696:Temperature
chemical_list: D011933:Reagent Kits, Diagnostic