title: Highly discordant serology against Trypanosoma cruzi in central Veracruz, Mexico: role of the antigen used for diagnostic.
abstract: BACKGROUND
  Chagas disease is a parasitic disease caused by the protozoan parasite Trypanosoma cruzi. In Mexico, the burden of the disease is difficult to estimate and improving surveillance for Chagas disease is an important priority. We aimed here at determining the seroprevalence of T. cruzi infection in humans in a rural community in Veracruz.
  
  
  METHODS
  Serum samples (196) were analyzed for T. cruzi infection using five enzyme-linked immunosorbent assay (ELISA) tests: two in-house tests based on crude parasite extract and three commercial ELISA kits. Because of highly discordant results, we further explored the importance of parasite antigens and strains by western-blot analysis.
  
  
  RESULTS
  A total of 74 samples (37.7 %) were reactive with at least one ELISA, but discordance among tests was very high. The best agreement was between Chagatest recombinant and Chagatek ELISA (Kappa index = 0.798). The agreement between other combinations of tests ranged from 0.038 to 0.518. Discordant samples were confirmed by western-blot analysis using up to nine parasite strains, giving a seroprevalence of 33.7 %.
  
  
  CONCLUSIONS
  Commercial tests had a very limited ability to detect T. cruzi infection in the study population. In-house tests based on crude parasite antigens showed a greater sensitivity but were still unable to detect all cases of T. cruzi infection, even when based on a local parasite strain. The high seroprevalence confirmed the hyper-endemicity of T. cruzi infection in the region. Reliable epidemiological surveillance of Chagas disease will require the development of improved diagnostic tests.
authors.affiliation: Doctorado en Ciencias Biomédicas, Universidad Veracruzana, Xalapa, Veracruz, Mexico. daguzman@uv.mx.|LADISER Inmunología y Biología Molecular, Facultad de Ciencias Químicas, Universidad Veracruzana, Orizaba, Veracruz, Mexico. daguzman@uv.mx.
authors.forename: Daniel
authors.initials: D
authors.lastname: Guzmán-Gómez
authors.affiliation: LADISER Inmunología y Biología Molecular, Facultad de Ciencias Químicas, Universidad Veracruzana, Orizaba, Veracruz, Mexico. aralopez@uv.mx.|Centro de Investigaciones Biomédicas, Universidad Veracruzana, Xalapa, Veracruz, Mexico. aralopez@uv.mx.
authors.forename: Aracely
authors.initials: A
authors.lastname: López-Monteon
authors.affiliation: Doctorado en Ciencias Biomédicas, Universidad Veracruzana, Xalapa, Veracruz, Mexico. solagunes@gmail.com.|LADISER Inmunología y Biología Molecular, Facultad de Ciencias Químicas, Universidad Veracruzana, Orizaba, Veracruz, Mexico. solagunes@gmail.com.
authors.forename: María
authors.initials: M
authors.lastname: de la Soledad Lagunes-Castro
authors.affiliation: LADISER Inmunología y Biología Molecular, Facultad de Ciencias Químicas, Universidad Veracruzana, Orizaba, Veracruz, Mexico. karola_5106@hotmail.com.
authors.forename: Carolina
authors.initials: C
authors.lastname: Álvarez-Martínez
authors.affiliation: LADISER Inmunología y Biología Molecular, Facultad de Ciencias Químicas, Universidad Veracruzana, Orizaba, Veracruz, Mexico. manuel.365@hotmail.com.
authors.forename: Manuel Jesús
authors.initials: MJ
authors.lastname: Hernández-Lutzon
authors.affiliation: Laboratorio de Parasitología, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico. edumonte@tulane.edu.|Department of Tropical Medicine, Tulane University, School of Public Health and Tropical Medicine, New Orleans, LA, USA. edumonte@tulane.edu.
authors.forename: Eric
authors.initials: E
authors.lastname: Dumonteil
authors.affiliation: LADISER Inmunología y Biología Molecular, Facultad de Ciencias Químicas, Universidad Veracruzana, Orizaba, Veracruz, Mexico. angramos@uv.mx.|Centro de Investigaciones Biomédicas, Universidad Veracruzana, Xalapa, Veracruz, Mexico. angramos@uv.mx.
authors.forename: Angel
authors.initials: A
authors.lastname: Ramos-Ligonio
mesh_terms: D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology*; D015153:Blotting, Western; D014355:Chagas Disease / Q000175:diagnosis* / Q000453:epidemiology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D008800:Mexico / Q000453:epidemiology; D012424:Rural Population; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies; D012698:Serologic Tests / Q000379:methods*; D014349:Trypanosoma cruzi / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan