title: Unrecognized Emergence of Chikungunya Virus during a Zika Virus Outbreak in Salvador, Brazil.
abstract: Chikungunya virus (CHIKV) entered Brazil in 2014, causing a large outbreak in Feira de Santana, state of Bahia. Although cases have been recorded in Salvador, the capital of Bahia, located ~100 km of Feira de Santana, CHIKV transmission has not been perceived to occur epidemically, largely contrasting with the Zika virus (ZIKV) outbreak and ensuing complications reaching the city in 2015.
  
  
  
  This study aimed to determine the intensity of CHIKV transmission in Salvador between November 2014 and April 2016. Results of all the CHIKV laboratory tests performed in the public sector were obtained and the frequency of positivity was analyzed by epidemiological week. Of the 2,736 tests analyzed, 456 (16.7%) were positive. An increasing in the positivity rate was observed, starting in January/2015, and peaking at 68% in August, shortly after the exanthematous illness outbreak attributed to ZIKV.
  
  
  
  Public health authorities and health professionals did not immediately detect the increase in CHIKV cases, likely because all the attention was directed to the ZIKV outbreak and ensuing complications. It is important that regions in the world that harbor arbovirus vectors and did not experience intense ZIKV and CHIKV transmission be prepared for the potential co-emergence of these two viruses.
authors.affiliation: Secretaria Municipal de Saúde de Salvador, Salvador, Bahia, Brazil.
authors.forename: Cristiane W
authors.initials: CW
authors.lastname: Cardoso
authors.affiliation: Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.|Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Mariana
authors.initials: M
authors.lastname: Kikuti
authors.affiliation: Secretaria Municipal de Saúde de Salvador, Salvador, Bahia, Brazil.
authors.forename: Ana Paula P B
authors.initials: AP
authors.lastname: Prates
authors.affiliation: Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.|Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Igor A D
authors.initials: IA
authors.lastname: Paploski
authors.affiliation: Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.
authors.forename: Laura B
authors.initials: LB
authors.lastname: Tauro
authors.affiliation: Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.
authors.forename: Monaise M O
authors.initials: MM
authors.lastname: Silva
authors.affiliation: Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.
authors.forename: Perla
authors.initials: P
authors.lastname: Santana
authors.affiliation: Laboratório Central de Saúde Pública, Secretaria de Saúde do Estado da Bahia, Salvador, Bahia, Brazil.
authors.forename: Marta F S
authors.initials: MF
authors.lastname: Rego
authors.affiliation: Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.|Faculdade de Medicina, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Mitermayer G
authors.initials: MG
authors.lastname: Reis
authors.affiliation: Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.|Department of Environmental Sciences, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Uriel
authors.initials: U
authors.lastname: Kitron
authors.affiliation: Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.|Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Guilherme S
authors.identifier: 0000-0002-6798-2059
authors.initials: GS
authors.lastname: Ribeiro
mesh_terms: D001938:Brazil / Q000453:epidemiology; D065632:Chikungunya Fever / Q000453:epidemiology / Q000821:virology*; D002646:Chikungunya virus / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D004196:Disease Outbreaks; D006801:Humans; D011634:Public Health; D012621:Seasons; D000071244:Zika Virus / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D000071243:Zika Virus Infection / Q000453:epidemiology / Q000821:virology*