Survey on Non-Human Primates and Mosquitoes Does not Provide Evidences of Spillover/Spillback between the Urban and Sylvatic Cycles of Yellow Fever and Zika Viruses Following Severe Outbreaks in Southeast Brazil.

In the last decade, Flaviviruses such as yellow fever (YFV) and Zika (ZIKV) have expanded their transmission areas. These viruses originated in Africa, where they exhibit both sylvatic and interhuman transmission cycles. In Brazil, the risk of YFV urbanization has grown, with the sylvatic transmission approaching the most densely populated metropolis, while concern about ZIKV spillback to a sylvatic cycle has risen. To investigate these health threats, we carried out extensive collections and arbovirus screening of 144 free-living, non-human primates (NHPs) and 5219 mosquitoes before, during, and after ZIKV and YFV outbreaks (2015-2018) in southeast Brazil. ZIKV infection was not detected in any NHP collected at any time. In contrast, current and previous YFV infections were detected in NHPs sampled between 2017 and 2018, but not before the onset of the YFV outbreak. Mosquito pools screened by high-throughput PCR were positive for YFV when captured in the wild and during the YFV outbreak, but were negative for 94 other arboviruses, including ZIKV, regardless of the time of collection. In conclusion, there was no evidence of YFV transmission in coastal southeast Brazil before the current outbreak, nor the spread or establishment of an independent sylvatic cycle of ZIKV or urban Aedes aegypti transmission of YFV in the region. In view of the region's receptivity and vulnerability to arbovirus transmission, surveillance of NHPs and mosquitoes should be strengthened and continuous.

Haemagogus leucocelaenus and Haemagogus janthinomys are the primary vectors in the major yellow fever outbreak in Brazil, 2016-2018.

The yellow fever virus (YFV) caused a severe outbreak in Brazil in 2016-2018 that rapidly spread across the Atlantic Forest in its most populated region without viral circulation for almost 80 years. A comprehensive entomological survey combining analysis of distribution, abundance and YFV natural infection in mosquitoes captured before and during the outbreak was conducted in 44 municipalities of five Brazilian states. In total, 17,662 mosquitoes of 89 species were collected. Before evidence of virus circulation, mosquitoes were tested negative but traditional vectors were alarmingly detected in 82% of municipalities, revealing high receptivity to sylvatic transmission. During the outbreak, five species were found positive in 42% of municipalities. Haemagogus janthinomys and Hg. leucocelaenus are considered the primary vectors due to their large distribution combined with high abundance and natural infection rates, concurring together for the rapid spread and severity of this outbreak. Aedes taeniorhynchus was found infected for the first time, but like Sabethes chloropterus and Aedes scapularis, it appears to have a potential local or secondary role because of their low abundance, distribution and infection rates. There was no evidence of YFV transmission by Aedes albopictus and Aedes aegypti, although the former was the most widespread species across affected municipalities, presenting an important overlap between the niches of the sylvatic vectors and the anthropic ones. The definition of receptive areas, expansion of vaccination in the most affected age group and exposed populations and the adoption of universal vaccination to the entire Brazilian population need to be urgently implemented.

Distribuição espacial e temporal de Aedes aegypti e da infecção por vírus dengue no município do Rio de Janeiro / Spatial and temporal distribution of aedes aegypti and infection of dengue virus in Rio de Janeiro

Aedes aegypti é o único vetor natural comprovado de DENV no Brasil. O DENV é um arbovírus disseminado em grande parte do país, como no estado do Rio de Janeiro, onde epidemias cíclicas de dengue têm sido registradas, especialmente a cada introdução e re-emergência de sorotipos, como ocorreu com DENV-1 em 2010-2011 e DENV-4 em 2011. O presente trabalho baseou-se em coletas de adultos do gênero Aedes em armadilha de oviposição (MosquiTrap) e de fêmeas em busca de fonte sanguínea (BG-Sentinela). As armadilhas foram instaladas em três áreas fixas e sete áreas móveis de novembro de 2012 a julho de 2013 no município do Rio de Janeiro e foram comparadas com resultados de ovitrampas instaladas pela Secretaria Municipal de Saúde-RJ em regiões de positividade de ovitrampa. Os mosquitos coletados foram examinados quanto à infecção por DENV, através de RT-PCR. Foram coletados 2822 espécimes fêmeas e machos de Ae. aegypti e Ae. albopictus nas 63 áreas móveis e nas três áreas fixas. Ae. aegypti foi predominantemente detectado ao longo do estudo, independente do mês e local de coleta com 93,5 por cento do total de fêmeas coletadas. Já Ae. albopictus, com 6,5 por cento do total de fêmeas coletadas, foi essencialmente focal em áreas de maior cobertura vegetal. A distribuição de Ae. aegypti foi heterogênea no tempo e no espaço, com maior detecção nos meses mais quentes e chuvosos, de dezembro a março. Um episódio de alta precipitação ocorrida em janeiro pode ter interferido com os resultados das coletas em MosquiTrap. A avaliação espacial de ovitrampas positivas não pareceu constituir um indicador eficiente para a predição do da infestação por fêmeas adultas, pois não houve coincidência espacial entre o aumento da positividade de ovitrampas e a média de fêmeas coletadas em MosquiTrap.

A alta positividade verificada nas coletas em áreas móveis ressalta a importância da aleatoriedade na coleta de mosquitos infectados. Foi visto ainda que os padrões de distribuição de mosquitos infectados coincidiram no tempo com a notificação de casos humanos de dengue clinicamente diagnosticados. Somente fêmeas Ae. aegypti foram encontradas, à exceção de um único pool positivos de machos para DENV. A taxa de infecção natural foi de apenas 0,95 por cento. O sorotipo prevalente em humanos foi o DENV-4, enquanto que o DENV-2 foi o sorotipo mais prevalente em mosquitos. A discrepância qualitativa entre a frequência das infecções pelos sorotipos de DENV em mosquitos e humanos somada à detecção de machos de Ae. aegypti positivos sugere a ocorrência da manutenção silenciosa da transmissão de sorotipos de DENV que podem emergir/ reemergir de forma epidêmica a qualquer momento. Devida a complexidade da dinâmica da dengue, a avaliação de risco na dinâmica espacial e temporal deve ser baseada na observação e na compreensão de vários fatores que a influencia. (AU)

Aedes aegypti is the only natural vector of DENV in Brazil. DENV is anarbovirus widespread in most of Brazil, as well as in the city of Rio de Janeiro. In Riode Janeiro cyclical epidemics of dengue fever have been recorded especially at eachintroduction and reemergence of serotypes, as those occurred in 2010-2011 byDENV-1 and by DENV-4 in 2011. This study was based on samples of adults of thegenus Aedes collected MosquiTrap and BG-Sentinel. The traps were installed inthree fixed areas and seven itinerant areas from November 2012 to July 2013 in thecity of Rio de Janeiro. The results of our traps were compared with the results fromegg traps installed by the Municipal Secretary of Health-RJ in positive egg traps inthe same city. The mosquitoes collected were examined for DENV infection by RTPCR.A total of 2822 female and male Ae. aegypti and Ae. albopictus were collectedin 63 itinerant areas and in three fixed areas. Ae. aegypti was predominantlydetected throughout the study regardless of the month and the collection site with 93.5 percent of females collected. Ae. albopictus represented 6.5 percent of the total females,collected essentially on areas of vegetation cover. The distribution of Ae. aegyptiwas heterogeneous in time and space, with greater detection in the warmer and rainymonths. An episode of high rainfall that occurred in January may have interfered withthe results in MosquiTrap. Spatial assessment of positive egg traps does not appearto be an efficient indicator for the prediction of infestation by adult females as therewas no spatial coincidence between increased positivity egg traps and the average offemales collected in MosquiTrap.

The high positivity in collections in itinerant areashighlights the importance of randomness in sampling infected mosquitoes. It wasalso seen that the distribution patterns of infected mosquitoes coincided in time withthe reporting of human cases of clinically diagnosed dengue fever. Only Ae. aegyptifemales were found infected, except for a single pool of males. The rate of naturalmosquito infection was only 0.95 percent whose prevalent serotype in humans was DENV-4, DENV-2 was the most prevalent found in mosquitoes. The qualitative discrepancybetween the frequency of DENV serotypes infections in mosquitoes and humanscombined with the detection of DENV positive Ae. aegypti males suggests theoccurrence of silent transmission maintenance of DENV serotypes that can emerge/reemerge in epidemic form at any time. Due to the complexity of the dynamics ofdengue, risk evaluation on the spatial and temporal dynamics should be based onthe observation and the simultaneous understanding of its various influencing factors. (AU)

Distribuição espacial e temporal de aedes aegypti e da infecção por vírus dengue no município do Rio de Janeiro / Spatial and temporal distribution of aedes aegypti and infection of dengue virus in Rio de Janeiro

Aedes aegypti é o único vetor natural comprovado de DENV no Brasil. O DENV é um arbovírus disseminado em grande parte do país, como no estado do Rio de Janeiro, onde epidemias cíclicas de dengue têm sido registradas, especialmente a cada introdução e re-emergência de sorotipos, como ocorreu com DENV-1 em 2010-2011 e DENV-4 em 2011. O presente trabalho baseou-se em coletas de adultos do gênero Aedes em armadilha de oviposição (MosquiTrap) e de fêmeas em busca de fonte sanguínea (BG-Sentinela). As armadilhas foram instaladas em três áreas fixas e sete áreas móveis de novembro de 2012 a julho de 2013 no município do Rio de Janeiro e foram comparadas com resultados de ovitrampas instaladas pela Secretaria Municipal de Saúde-RJ em regiões de positividade de ovitrampa. Os mosquitos coletados foram examinados quanto à infecção por DENV, através de RT-PCR. Foram coletados 2822 espécimes fêmeas e machos de Ae. aegypti e Ae. albopictus nas 63 áreas móveis e nas três áreas fixas. Ae. aegypti foi predominantemente detectado ao longo do estudo, independente do mês e local de coleta com 93,5% do total de fêmeas coletadas...

Aedes aegypti is the only natural vector of DENV in Brazil. DENV is anarbovirus widespread in most of Brazil, as well as in the city of Rio de Janeiro. In Rio de Janeiro cyclical epidemics of dengue fever have been recorded especially at each introduction and reemergence of serotypes, as those occurred in 2010-2011 byDENV-1 and by DENV-4 in 2011. This study was based on samples of adults of the genus Aedes collected MosquiTrap and BG-Sentinel. The traps were installed inthree fixed areas and seven itinerant areas from November 2012 to July 2013 in the city of Rio de Janeiro. The results of our traps were compared with the results fromegg traps installed by the Municipal Secretary of Health-RJ in positive egg traps inthe same city. The mosquitoes collected were examined for DENV infection by RTPCR.A total of 2822 female and male Ae. aegypti and Ae. albopictus were collectedin 63 itinerant areas and in three fixed areas. Ae. aegypti was predominant ly detected throughout the study regardless of the month and the collection site with 93.5 percent of females collected...