title: Unexpectedly high leprosy seroprevalence detected using a random surveillance strategy in midwestern Brazil: A comparison of ELISA and a rapid diagnostic test.
abstract: Leprosy diagnosis is mainly based on clinical evaluation, although this approach is difficult, especially for untrained physicians. We conducted a temporary campaign to detect previously unknown leprosy cases in midwestern Brazil and to compare the performance of different serological tests.
  
  
  
  A mobile clinic was stationed at the main bus terminal in Brasília, Brazil. Volunteers were quizzed and given a clinical exam to allow categorization as either patients, known contacts of patients or non-contacts, and blood was collected to determine anti-PGL-I and anti-LID-1 antibody titers by ELISA and by the NDO-LID rapid test. New cases of leprosy and the impact of performing this broad random surveillance strategy were evaluated. Accuracy values and concordance between the test results were evaluated among all groups.
  
  
  
  Four hundred thirty-four individuals were evaluated, and 44 (10.1%) were diagnosed with leprosy. Borderline forms were the most frequent presentation. Both tests presented higher positivity in those individuals with multibacillary disease. Serological tests demonstrated specificities arround 70% for anti-PGL-1 and anti-LID ELISA; and arround 40% for NDO-LID. Sensitivities ranged from 48 to 62%. A substantial agreement between NDO-LID and ELISA with concomitant positive results was found within leprosy patients (Kappa index = 0.79 CI95% 0.36-1.22).
  
  
  
  The unexpectedly high leprosy prevalence in this population indicates ongoing community-based exposure to Mycobacterium leprae antigens and high rates of subclinical infection. All tests showed low specificity and sensitivity values and therefore cannot be considered for use as stand-alone diagnostics. Rather, considering their positivity among MB patients and non-patients, these tests can be considered effective tools for screening and identifying individuals at high risk who might benefit from regular monitoring.
authors.affiliation: Dermatology Division, Department of Medical Clinics, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Marco Andrey C
authors.initials: MA
authors.lastname: Frade
authors.affiliation: Dermatology Division, Department of Medical Clinics, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Natália A
authors.initials: NA
authors.lastname: de Paula
authors.affiliation: Dermatology Division, Department of Medical Clinics, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.|Dermatology Division, Department of Medical Clinics, Faculty of Medicine, University of Brasília, Brasília, Brazil.
authors.forename: Ciro M
authors.initials: CM
authors.lastname: Gomes
authors.affiliation: Dermatology Division, Department of Medical Clinics, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Vernal
authors.affiliation: Dermatology Division, Department of Medical Clinics, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Fred
authors.initials: F
authors.lastname: Bernardes Filho
authors.affiliation: Dermatology Division, Department of Medical Clinics, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Helena B
authors.initials: HB
authors.lastname: Lugão
authors.affiliation: Service of Dermatology, University of Oeste Paulista, Presidente Prudente, Brazil.
authors.forename: Marilda M M
authors.initials: MM
authors.lastname: de Abreu
authors.affiliation: Service of Dermatology, University of Oeste Paulista, Presidente Prudente, Brazil.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Botini
authors.affiliation: Infectious Diseases Research Institute, 1616 Eastlake Av. E, Seattle, WA, United States of America.
authors.forename: Malcolm S
authors.initials: MS
authors.lastname: Duthie
authors.affiliation: Colorado State University, Department of Microbiology, Immunology and Pathology, Fort Collins, CO, United States of America.
authors.forename: John S
authors.initials: JS
authors.lastname: Spencer
authors.affiliation: General Coordination of Leprosy and Eliminating Diseases, Surveillance Secretariat in Health, Brazilian Health Ministry, Brasília, Distrito Federal, Brazil.
authors.forename: Rosa Castália F R
authors.initials: RC
authors.lastname: Soares
authors.affiliation: Dermatology Division, Department of Medical Clinics, Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Norma T
authors.initials: NT
authors.lastname: Foss
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003955:Diagnostic Tests, Routine / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D007918:Leprosy / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009166:Mycobacterium leprae / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D018571:Sentinel Surveillance; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial