title: False-negative dengue cases in Roraima, Brazil: an approach regarding the high number of negative results by NS1 ag kits.
abstract: Serum samples from 150 NS1-negative (Platelia ELISA) patients presumptively diagnosed with dengue were analyzed by the TaqMan probed real-time reverse transcription PCR (TaqMan qRT-PCR) method. The qRT-PCR positive samples were tested for serotype by semi-nested RT-PCR and a qualitative immunochromatographic assay for IgG and IgM. Molecular detection methods showed 33 (22%) positive samples out of 150 NS1-antigen negative samples. Of these, 72% were collected up to day 2 after the onset of symptoms, when diagnostic sensitivity of NS1-antigen test assays is significantly enhanced. Most of the cases were not characterized as secondary infection. Twenty-eight samples were successfully serotyped, 75% of which for DENV-4, 14% for DENV-2, 7% for DENV-3 and 4% for DENV-1. These findings reaffirm the hyperendemic situation of the state of Roraima and suggest a lower sensitivity of the NS1 test, mainly when DENV-4 is the predominant serotype. Health care providers should therefore be aware of samples tested negative by NS1 antigen assays, especially when clinical symptoms and other laboratory data results show evidence of dengue infection.
authors.affiliation: Laboratório de Biologia Molecular, Centro de Estudos da Biodiversidade, Universidade Federal de Roraima, Boa Vista, RR, Brasil.
authors.forename: Pablo O A
authors.initials: PO
authors.lastname: Acosta
authors.affiliation: Laboratório de Biologia Molecular, Centro de Estudos da Biodiversidade, Universidade Federal de Roraima, Boa Vista, RR, Brasil.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Granja
authors.affiliation: Laboratório Central de Roraima, Boa Vista, RR, Brasil.
authors.forename: Cátia A
authors.initials: CA
authors.lastname: Meneses
authors.affiliation: Laboratório de Biologia Molecular, Centro de Estudos da Biodiversidade, Universidade Federal de Roraima, Boa Vista, RR, Brasil.
authors.forename: Ismael A S
authors.initials: IA
authors.lastname: Nascimento
authors.affiliation: Laboratório de Biologia Molecular, Centro de Estudos da Biodiversidade, Universidade Federal de Roraima, Boa Vista, RR, Brasil.
authors.forename: Débora D
authors.initials: DD
authors.lastname: Sousa
authors.affiliation: Laboratório de Biologia Molecular, Centro de Estudos da Biodiversidade, Universidade Federal de Roraima, Boa Vista, RR, Brasil.
authors.forename: Wilson P
authors.initials: WP
authors.lastname: Lima Júnior
authors.affiliation: Instituto Leônidas e Maria Deane, Manaus, AM, Brasil.
authors.forename: Felipe Gomes
authors.initials: FG
authors.lastname: Naveca
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D001938:Brazil; D003715:Dengue / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay; D005188:False Negative Reactions; D006801:Humans; D011933:Reagent Kits, Diagnostic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D017361:Viral Nonstructural Proteins / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D011933:Reagent Kits, Diagnostic; D017361:Viral Nonstructural Proteins