Detection of Zika and dengue viruses in wild-caught mosquitoes collected during field surveillance in an environmental protection area in S��o Paulo, Brazil.
Karolina Morales Barrio-Nuevo, Mariana Sequetin Cunha, Adriana Luchs, Aristides Fernandes, Iray Maria Rocco, Luis Filipe Mucci, Renato Pereira de Souza, Ant��nio Ralph Medeiros-Sousa, Walter Ceretti-Junior, Mauro Toledo Marrelli
Author Information
Karolina Morales Barrio-Nuevo: Epidemiology Department, School of Public Health, University of S��o Paulo, S��o Paulo, Brazil.
Mariana Sequetin Cunha: Vector-borne Disease Laboratory, Virology Center, Adolfo Lutz Institute, S��o Paulo, Brazil.
Adriana Luchs: Enteric Disease Laboratory, Virology Center, Adolfo Lutz Institute, S��o Paulo, Brazil.
Aristides Fernandes: Epidemiology Department, School of Public Health, University of S��o Paulo, S��o Paulo, Brazil.
Iray Maria Rocco: Vector-borne Disease Laboratory, Virology Center, Adolfo Lutz Institute, S��o Paulo, Brazil.
Luis Filipe Mucci: Superintendency for the Control of Endemic Diseases, State Health Department, S��o Paulo, Brazil.
Renato Pereira de Souza: Vector-borne Disease Laboratory, Virology Center, Adolfo Lutz Institute, S��o Paulo, Brazil.
Ant��nio Ralph Medeiros-Sousa: Epidemiology Department, School of Public Health, University of S��o Paulo, S��o Paulo, Brazil.
Walter Ceretti-Junior: Epidemiology Department, School of Public Health, University of S��o Paulo, S��o Paulo, Brazil.
Mauro Toledo Marrelli: Epidemiology Department, School of Public Health, University of S��o Paulo, S��o Paulo, Brazil. ORCID
Species of the genus Flavivirus are widespread in Brazil and are a major public health concern. The country's largest city, S��o Paulo, is in a highly urbanized area with a few forest fragments which are commonly used for recreation. These can be considered to present a potential risk of flavivirus transmission to humans as they are home simultaneously to vertebrate hosts and mosquitoes that are potential flavivirus vectors. The aim of this study was to conduct flavivirus surveillance in field-collected mosquitoes in the Capivari-Monos Environmental Protection Area (EPA) and identify the flavivirus species by sequence analysis in flavivirus IFA-positive pools. Monthly mosquito collections were carried out from March 2016 to April 2017 with CO2-baited CDC light traps. Specimens were identified morphologically and grouped in pools of up to 10 individuals according to their taxonomic category. A total of 260 pools of non-engorged females were inoculated into C6/36 cell culture, and the cell suspensions were analyzed by indirect immunofluorescence assay (IFA) after the incubation period. IFA-positive pools were tested by qRT-PCR with genus-specific primers targeting the flavivirus NS5 gene to confirm IFA-positive results and sequenced to identify the species. Anopheles cruzii (19.5%) and Wyeomyia confusa (15.3%) were the most frequent vector species collected. IFA was positive for flaviviruses in 2.3% (6/260) of the sample pools. This was confirmed by qRT-PCR in five pools (83.3%). All five flavivirus-positive pools were successfully sequenced and the species identified. DENV serotype 2 (DENV-2) was detected in Culex spp. and Culex vaxus pools, while ZIKV was identified in An. cruzii, Limatus durhamii and Wy. confusa pools. To the best of our knowledge, detection of flavivirus species of medical importance has never previously been reported in these species of wild-caught mosquitoes. The finding of DENV-2 and ZIKV circulating in wild mosquitoes suggests the existence of an enzootic cycle in the area. In-depth studies of DENV-2 and ZIKV, including investigation of mosquito infection, vector competence and infection in sylvatic hosts, are needed to shed light on the transmission dynamics of these important viruses and the potential risk of future outbreaks of DENV-2 and ZIKV infections in the region.
