Serodiscordance in chronic Chagas disease diagnosis: a real problem in non-endemic countries.
According to the WHO, chronic Chagas disease (CD) diagnosis is based on two serological techniques. To establish a definitive diagnosis, the results must be concordant. In cases of discordances, the WHO proposes repeating serology in a new sample, and if results remain inconclusive, a confirmatory test should be performed. This study, conducted at two Tropical Medicine Units in Europe over 4 years, aims to assess the diagnostic yield of TESA- (trypomastigote excreted-secreted antigens) blot as a confirmatory technique in patients with inconclusive and discordant results. Of 4939 individuals screened, 1124 (22.7%) obtained positive results and 165 (3.3%) discordant results. Serology was repeated in 88/165 sera and discrepancies were solved in 25/88 (28.4%) cases. Patients without a definitive diagnosis were classified in two different groups: Group 1, including patients with inconclusive results despite retesting (n = 63), and Group 2, including patients with discordant results not retested (n = 77). TESA-blot was performed for all of Group 1 and 39/77 of Group 2 and was positive for 33/63 (52.4%) and 21/39 (53.8%), respectively. Analysis of Group 1 results showed a moderate agreement between results of the ELISA based on native antigen and TESA-blot (κ 0.53). In contrast, a clear disagreement was observed between the ELISA based on recombinant antigens and TESA-blot (κ <0). A sizeable proportion of patients are suspected to have CD with inconclusive results or in whom re-testing is not feasible. TESA-blot was positive in half of these patients, highlighting the need for a confirmatory assay in European centres caring for exposed individuals.
Microbiology Department, Vall d'Hebron University Hospital, Universitat Autònoma de Barcelona, PROSICS, Barcelona, Spain. Electronic address: zmoure@vhebron.net.
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Moure
Centre for Tropical Diseases, Hospital 'Sacro Cuore-Don Calabria', Negrar, Italy; Global Health Centre of Tuscany Region, Florence, Italy.
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Angheben
Infectious Diseases Department, Vall d'Hebron University Hospital, PROSICS, Barcelona, Spain.
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Molina
Centre for Tropical Diseases, Hospital 'Sacro Cuore-Don Calabria', Negrar, Italy; Global Health Centre of Tuscany Region, Florence, Italy.
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Gobbi
Microbiology Department, Vall d'Hebron University Hospital, Universitat Autònoma de Barcelona, PROSICS, Barcelona, Spain.
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Espasa
Centro de Epidemiologia Comunitaria y Medicina Tropical, Esmeraldas, Ecuador.
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Anselmi
Infectious Diseases Department, Vall d'Hebron University Hospital, PROSICS, Barcelona, Spain.
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Salvador
Service of Epidemiology and Laboratory for Tropical Diseases, Hospital 'Sacro Cuore-Don Calabria', Negrar, Italy.
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Tais
Infectious Diseases Department, Vall d'Hebron University Hospital, PROSICS, Barcelona, Spain.
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Sánchez-Montalvá
Microbiology Department, Vall d'Hebron University Hospital, Universitat Autònoma de Barcelona, PROSICS, Barcelona, Spain.
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Pumarola
Department of HIV/AIDS, Tuberculosis, Malaria and Neglected Diseases, Control of Neglected Tropical Diseases Department, WHO, Geneva, Switzerland.
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Albajar-Viñas
Microbiology Department, Vall d'Hebron University Hospital, Universitat Autònoma de Barcelona, PROSICS, Barcelona, Spain.
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Sulleiro
D000328:Adult; D000368:Aged; D000465:Algorithms; D015415:Biomarkers; D014355:Chagas Disease / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology / Q000469:parasitology; D002908:Chronic Disease; D000066491:Clinical Decision-Making; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012698:Serologic Tests; D013030:Spain / Q000453:epidemiology; D055815:Young Adult
D015415:Biomarkers
Chagas; Chronic; Inconclusive; Non-endemic; Serology