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Aedes mosquitoes, as vectors of medically important arthropod-borne viruses (arboviruses), constitute a major public health threat that requires entomological and epidemiological surveillance to guide vector control programs to prevent and reduce disease transmission. In this study, we present the collaborative effort of one year of mosquito-based arbovirus surveillance in two geographically distinct regions of Latin America (Nicaragua and Ecuador). Adult female mosquitoes were collected using backpack aspirators in over 2,800 randomly selected households (Nicaragua, Ecuador) and 100 key sites (Nicaragua) from eight distinct communities (Nicaragua: 2, Ecuador: 6). A total of 1,358 mosquito female pools were processed for RNA extraction and viral RNA detection using real-time RT-PCR. Ten positive dengue virus (DENV) pools were detected (3 in Nicaragua and 7 in Ecuador), all of which were found during the rainy season and matched the serotypes found in humans (Nicaragua: DENV-1 and DENV-4; Ecuador: DENV-2). Infection rates ranged from 1.13 to 23.13, with the Nicaraguan communities having the lowest infection rates. Our results demonstrate the feasibility of detecting DENV-infected Aedes mosquitoes in low-resource settings and underscore the need for targeted mosquito arbovirus sampling and testing, providing valuable insights for future surveillance programs in the Latin American region.
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Arboviruses transmitted by Culicidae insects are significant threats to human health, presenting dynamic transmission cycles and involving different vectors and hosts. The surveillance and characterization of the vectors involved in these cycles are crucial for understanding and preventing potential outbreaks. Therefore, we propose a strategy that we used for entomological surveillance of urban, rural, and sylvatic mosquitoes and to characterize natural infection by four major arboviruses.â¢Immature and adult mosquitoes were collected intra, peri and extradomicilie of urban and rural households, using different collection methodologies.â¢Mosquitoes were pooled or separated in head-thorax and abdomen, according to the species.â¢A multiplex nested RT-PCR (Reverse transcription polymerase chain reaction) method was used for the simultaneous detection of dengue virus (DENV), zika virus (ZIKV), chikungunya virus (CHIKV), and yellow fever virus (YFV).Overall, this strategy proved helpful for vectors surveillance at different ecosystems, as well as for implementing a low-cost molecular surveillance system that allows the early detection of potential outbreaks, and identify other potential vectors involved in viral transmission.
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The largest outbreak of sylvatic yellow fever virus (YFV) in eight decades was recorded in Brazil between 2016-2018. Besides human and NHP surveillance, the entomo-virological approach is considered as a complementary tool. For this study, a total of 2904 mosquitoes of the Aedes, Haemagogus and Sabethes genera were collected from six Brazilian states (Bahia, Goiás, Mato Grosso, Minas Gerais, Pará, and Tocantins) and grouped into 246 pools, which were tested for YFV using RT-qPCR. We detected 20 positive pools from Minas Gerais, 5 from Goiás, and 1 from Bahia, including 12 of Hg. janthinomys and 5 of Ae. albopictus. This is the first description of natural YFV infection in this species and warns of the likelihood of urban YFV re-emergence with Ae. albopictus as a potential bridge vector. Three YFV sequences from Hg. janthinomys from Goiás and one from Minas Gerais, as well as one from Ae. albopictus from Minas Gerais were clustered within the 2016-2018 outbreak clade, indicating YFV spread from Midwest and its infection in a main and likely novel bridging vector species. Entomo-virological surveillance is critical for YFV monitoring in Brazil, which could highlight the need to strengthen YFV surveillance, vaccination coverage, and vector control measures.
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Arboviruses transmitted by Aedes aegypti in urban environments have spread rapidly worldwide, causing great impacts on public health. The development of reliable and timely alert signals is among the most important steps in designing accurate surveillance systems for vector-borne diseases. In July and September 2017, we conducted a pilot study to improve an existing integrated surveillance system by using entomo-virological surveillance to prioritize areas to conduct active searches for individuals with arbovirus infection symptoms. Foz do Iguaçu City has a permanent entomo-virological surveillance system with approximately 3,500 traps to capture Aedes sp. in the adult stage. The Aedes aegypti females are captured alive and human samples are submitted to RT-qPCR (real-time qPCR) screening for DENV, ZIKV, and CHIKV diagnosis. Of the 55 Ae. aegypti mosquitoes tested in July 2017, seven (12.7%) were considered positive for DENV-2 and three (5.4%) for CHIKV. In September, we tested a sample of 54 mosquitoes, and 15 (27.7%) were considered infected by DENV-2. We created 25 circumferences with 150-m radius each to perform an active survey to identify symptomatic householders. In July, we selected one circumference, and five (35.7%) patients were positive for DENV, whereas two (14.3%) for CHIKV. In September, we selected four circumferences, and, from the 21 individuals sampled, nine (42.8%) were positive for DENV-2. A statistical model with a binomial response was used to estimate the number of cases in areas without active surveys, i.e., 20 circumferences. We estimated an additional 83 symptomatic patients (95% CI: 45-145) to be found in active searches, with 38 (95% CI: 18-72) of them confirming arbovirus infection. Arbovirus detection and serotyping in mosquitoes, but also in symptomatic individuals during active surveys, can provide an alert signal of early arbovirus transmission.
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Aedes , Arbovírus , Vírus da Dengue , Infecção por Zika virus , Zika virus , Adulto , Animais , Feminino , Humanos , Vírus da Dengue/genética , Mosquitos Vetores , Projetos Piloto , Zika virus/genética , Infecção por Zika virus/epidemiologia , Vigilância de Evento SentinelaRESUMO
Background: Two antigenically and genetically distinct lineages of influenza B viruses (B/Victoria and B/Yamagata) have been co-circulating worldwide since 2002. Virological surveillance is essential to differentiate between both lineages with a view to the annual updating of the B component for the trivalent or quadrivalent influenza vaccine composition. Methods: The samples analyzed in the present study were collected by influenza sentinel units located in the Southeast, Midwest, North, and Northeast regions of Brazil, part of the National Influenza Virus Surveillance Network, coordinated by the Ministry of Health of Brazil. A total of 870 influenza B positive samples by reverse transcription real - time polymerase chain reaction (RT-qPCR), collected during 2014, 2015, and 2016 influenza seasons, were submitted to the influenza B lineage genotyping panel for characterization as B/Yamagata or Victoria lineages using RT-qPCR. Results: Of the 197 samples analyzed in 2014, a total of 160 (81 %) corresponded to the B/Yamagata lineage, 19 (10 %) to the B/Victoria lineage, and 18 (9 %) to indeterminate lineages. Of the 190 samples analyzed in 2015, a total of 124 (65 %) corresponded to the B/Yamagata lineage; 55 (29 %) to the B/Victoria lineage, whereas 11 (6 %) were of indeterminate lineages. Of the 483 samples analyzed in 2016, a total of 297 (62 %) corresponded to the B /Victoria lineage; 174 (36 %) to the B/Yamagata lineage and 12 (2 %) to indeterminate lineages. This cross-sectional study revealed influenza B virus (IBV) infection in all age groups, and among them, the highest prevalence was observed in individuals between 11 and 49 years of age Our findings demonstrate the match between influenza B virus lineages recommended by the World Health Organization (WHO) for the trivalent vaccine composition to be used in the Southern Hemisphere (SH) and the predominant circulating viruses during the 2014, 2015, and 2016 seasons.
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Aedes spp. are considered the main vectors of dengue (DENV), Zika (ZIKV) and chikungunya (CHIKV) viruses in the world. Arbovirus detection in Aedes mosquitoes can alert authorities to possible outbreaks, reducing the impact of these diseases. The purpose of this study was to perform an operational strategy for virological surveillance of DENV, ZIKV and CHIKV in adult Aedes aegypti and Aedes albopictus mosquitoes captured at different key-sites in an endemic urban area of the Northeast Region of Brazil, with the prospect of discussing its role as part of an alert system for outbreaks in critical areas. Residential and non-residential premises located in areas of recent of transmission of these arboviruses were selected for adult mosquito collection in the rainy season (July) of 2018. A total of 1068 adult mosquitoes were collected: 946 Culex quinquefasciatus (88.6%), 118 Ae. aegypti (11.0%), two Ae. albopictus (0.2%) and two Aedes taeniorhynchus (0.2%). Among the premises surveyed, recycling points (Nâ¯=â¯48, 40.7%), municipal schools (Nâ¯=â¯36, 30.5%) and junkyards (Nâ¯=â¯31, 26.2%) were the places with the highest frequency of adult Ae. aegypti. Health units (including primary health care facilities and one hospital) (Nâ¯=â¯23; 19.5%) together with residential premises (Nâ¯=â¯11; 9.3%) presented the lowest frequencies. Total RNAs of the samples were extracted from Aedes mosquitoes and a nested reverse transcription (RT) polymerase chain reaction (PCR) assay for detecting and typing DENV, ZIKV and CHIKV was performed. From the 37 Aedes spp. pools analyzed (35 Ae. aegypti, one Ae. albopictus and one Ae. taeniorhynchus), seven were positive for DENV-3, including three pools containing Ae. aegypti females, one containing an Ae. aegypti engorged female and three comprised of Ae. aegypti males. The positive pools were composed of mosquitoes collected in public schools, health units, junkyards, recycling points and residential premises. Our findings reinforce the importance of continuous virological surveillance in Aedes mosquitoes, as a useful tool for detecting arboviruses circulation in vulnerable areas, even in low infestation seasons.
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Aedes/virologia , Vírus Chikungunya/isolamento & purificação , Vírus da Dengue/isolamento & purificação , Zika virus/isolamento & purificação , Adulto , Animais , Doenças Endêmicas/estatística & dados numéricos , Feminino , Humanos , Masculino , Mosquitos Vetores/virologiaRESUMO
OBJECTIVE: To study the distribution of vertical transmission of dengue viruses in field-collected Aedes aegypti larvae in the municipality of Arroyo Naranjo in Havana, Cuba. METHODS: Aedes aegypti larvae and pupae were collected monthly between September 2013 and July 2014 in the seven Municipal Health Areas of Arroyo Naranjo. Pools formed of 30-55 larvae were examined through PCR and sequencing to detect the presence of each serotype. RESULTS: We analysed 111 pools of larvae and pupae (4102 individuals) of which 37 tested positive for at least one DENV. More than one DENV type was observed in 10 of the 37 positive pools. Infected pools were detected every month, except in January, suggesting a sustained circulation of DENV in the vector populations. DENV-1 and DENV-3 were the most frequent and dispersed, though all four DENV types were detected. Nucleotide sequencing from positive pools confirmed RT-PCR results for DENV-1 (genotype V), DENV-3 (genotype III) and DENV-4 (genotype II). DENV-2 was detected by RT-PCR but could not be confirmed by nucleotide sequencing. CONCLUSION: Our study of the distribution of natural vertical transmission of dengue virus types highlights extrinsic virus activity patterns in the area and could be used as a new surveillance tool.
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Aedes/virologia , Vírus da Dengue , Transmissão Vertical de Doenças Infecciosas/estatística & dados numéricos , Mosquitos Vetores/virologia , Análise Espaço-Temporal , Animais , Cidades , CubaRESUMO
RESUMEN Una cepa triple reasortante del virus Influenza A emergió en al año 2009 dando origen a una pandemia que alcanzó a Paraguay en junio del mismo año. Con el fin de investigar la evolución genética del virus influenza A (H1N1) pdm09 en Paraguay fueron analizadas las secuencias nucleotídicas del Gen de la Hemaglutinina de 20 cepas de Influenza A(H1N1)pdm09, aisladas en el Centro Nacional de Influenza de Paraguay entre los años 2009 y 2016, y secuenciadas en el Centro Colaborador de OPS/OMS en Atlanta USA. El análisis filogenético muestra la circulación de al menos 5 grupos genéticos bien diferenciados de Influenza A(H1N1)pdm09 en Paraguay desde el 2009. Solamente los virus aislados en el 2016 pertenecen al sub Grupo genético 6B.1 en el cual se encuentra la actual cepa vacunal A/Michigan/45/2015 recomendada para el hemisferio Sur desde el año 2017. Los virus circulantes en años anteriores pertenecen a grupos antigénicamente indistinguibles de la cepa vacunal previa A/California/7/2009. No se encontraron diferencias resaltantes en las secuencias de los virus, relacionadas a severidad clínica ni a distribución geográfica. Los resultados de este estudio reafirman la necesidad de una vigilancia virológica sistemática para orientar el establecimiento de estrategias adecuadas de prevención y control de la influenza.
ABSTRACT A triple reassortant strain of Influenza A virus emerged in 2009, leading to a pandemic that reached Paraguay by June the same year. In order to investigate the genetic evolution of influenza A (H1N1)pdm09 virus in Paraguay, we analized the nucleotide sequences of the Hemagglutinin gene of 20 Influenza A (H1N1)pdm09 strains, isolated at the Paraguayan National Influenza Centre between 2009 and 2016, and sequenced at the PAHO/WHO Collaborating Center in Atlanta, USA. Phylogenetic analysis shows the circulation of at least 5 well-differentiated genetic groups of Influenza A (H1N1) pdm09 in Paraguay since 2009. Only the viruses isolated in 2016 belong to genetic subgroup 6B.1, the same as the current vaccine strain A/Michigan/45/2015, recommended for the Southern hemisphere since 2017. The viruses circulated previous years belong to groups antigenically indistinguishable from the previous vaccine strain A/California/7/2009. No significant differences were found in sequences of the viruses, related to clinical severity or geographic distribution. The results of this study reaffirm the need for systematic virological surveillance to guide the establishment of adequate strategies for the prevention and control of influenza.
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Dengue virus (DENV) is the most frequent arbovirus worldwide. In this study, we report a large outbreak in Mato Grosso State (MT). Serum samples from 604 patients with acute febrile illness for less than five days were inoculated in C6/36 cells, then infected cells were subjected to an indirect immunofluorescence test for DENV serotypes and yellow fever virus. Serum samples were submitted to a multiplex-semi-nested-RT-PCR for 11 flaviviruses. DENV-4 was isolated in 150/604 (24.8%) and DENV-1 in 19/604 (3.1%) specimens. By RT-PCR, 331 (54.8%) samples tested positive for DENV; 321 had single infections (DENV-4 n = 305; DENV-1 n = 15; DENV-3 n = 1), nine had co-infections of DENV-1/DENV-4, and one of DENV-2/DENV-4. DENV-4 was detected in 315/331 (95.2%) positive patients from 17 municipalities, and DENV-1 in 24/331 (7.2%) patients from five cities in north-central MT and the city of Cuiaba. The incidence of infection was higher in patients aged 20-39 (142/331; 42.9%). The NS5 partial nucleotide sequence of DENV-1 was most similar to that of genotype V, DENV-2 to Southeast Asian/American, DENV-3 to genotype III, and DENV-4 to genotype II strains, considered the most frequent strains in Brazil. This outbreak coincided with the introduction of DENV-4 in the state. Cuiaba was hyperendemic for the four DENV serotypes, highlighting the necessity for arbovirus surveillance in MT.
O vírus da dengue (DENV) é o arbovirus mais frequente no mundo. Neste estudo, é relatada uma epidemia de grandes proporções no estado de Mato Grosso (MT). Amostras de soro de 604 pacientes com doença febril aguda a menos de 5 dias foram inoculadas em células C6/36 seguida de Imunofluorescência indireta para os sorotipos do DENV e vírus da febre amarela e submetidas a multiplex-semi-nested-RT-PCR para 11 flavivírus. O DENV-4 foi isolado em 150/604 (24,8%) e DENV-1 em 19/604 (3,1%) amostras. Por RT-PCR, 331 (54,8%) pacientes foram positivos para DENV; 321 com infecções únicas (DENV-4 n=305; DENV-1 n=15; DENV-3 n=1), nove co-infecções entre DENV-1/DENV-4 e uma com DENV-2/DENV-4. O DENV-4 foi detectado em 315/331 (95,2%) pacientes de 17 municípios e o DENV-1 em 24/331 (7,2%) pacientes de 5 cidades da região centro-norte de MT e em Cuiabá. A incidência de infecção foi maior em pacientes de 20-39 anos (142/331; 42,9%). As sequências de nucleotídeos de região do gene NS5 do DENV-1 apresentaram maior similaridade com o genótipo V, do DENV-2 com Sudeste Asiático/Americano, DENV-3 com genótipo III e DENV-4 com genótipo II, considerados os mais frequentes no Brasil. Esta epidemia coincidiu com a introdução do DENV-4 no estado. Cuiabá foi considerada hiperendêmica para os quatro sorotipos do DENV, ressaltando a necessidade de vigilância para arbovírus em MT.
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Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Gravidez , Adulto Jovem , DNA Viral/isolamento & purificação , Vírus da Dengue/genética , Dengue/epidemiologia , Surtos de Doenças/estatística & dados numéricos , Sorogrupo , Brasil/epidemiologia , DNA Viral/genética , Dengue/sangue , Imunofluorescência , Febre/epidemiologia , Reação em Cadeia da Polimerase/métodos , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
OBJECTIVE: To present results of virological surveillance and epidemiological aspects of dengue in the State of Rio Grande do Norte, Brazil. METHODS: A total of 1581 cases, reported from 2010 to 2012 at various health centres in the state, were analysed by viral isolation and/or RT-PCR for viral detection and typing. To identify whether different genotypes were circulating in the state during this period, sequencing of the complete E gene for DENV (1485 bp in length) was performed directly from patient serum samples. RESULTS: All four serotypes of dengue virus circulated in Rio Grande do Norte, with the introduction of DENV-4 in the state in 2011. In 2012, DENV-4 represented 100% of positive confirmed cases. 53.97% of cases occurred in Natal. Case numbers peaked in April (21%) and May (23%). Genetic characterisation of circulating strains confirmed the circulation of genotypes V, south-east Asian/American and II, respectively, for DENV-1, DENV-2 and DENV-4. CONCLUSIONS: This work furthers a better understanding of dengue viruses in the State of Rio Grande do Norte. Strengthening control efforts in the region is important considering the impact of dengue.
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Vírus da Dengue/genética , Dengue/epidemiologia , Epidemias , Genótipo , Filogenia , Adolescente , Adulto , Brasil/epidemiologia , Criança , Pré-Escolar , Dengue/virologia , Surtos de Doenças , Humanos , Lactente , Recém-Nascido , Pessoa de Meia-Idade , Vigilância da População , Prevalência , Sorotipagem/métodos , Adulto JovemRESUMO
The dengue virus (DENV), which is frequently involved in large epidemics, and the yellow fever virus (YFV), which is responsible for sporadic sylvatic outbreaks, are considered the most important flaviviruses circulating in Brazil. Because of that, laboratorial diagnosis of acute undifferentiated febrile illness during epidemic periods is frequently directed towards these viruses, which may eventually hinder the detection of other circulating flaviviruses, including the Saint Louis encephalitis virus (SLEV), which is widely dispersed across the Americas. The aim of this study was to conduct a molecular investigation of 11 flaviviruses using 604 serum samples obtained from patients during a large dengue fever outbreak in the state of Mato Grosso (MT) between 2011 and 2012. Simultaneously, 3,433 female Culex spp. collected with Nasci aspirators in the city of Cuiabá, MT, in 2013, and allocated to 409 pools containing 1-10 mosquitoes, were also tested by multiplex semi-nested reverse transcription PCR for the same flaviviruses. SLEV was detected in three patients co-infected with DENV-4 from the cities of Cuiabá and Várzea Grande. One of them was a triple co-infection with DENV-1. None of them mentioned recent travel or access to sylvatic/rural regions, indicating that transmission might have occurred within the metropolitan area. Regarding mosquito samples, one pool containing one Culex quinquefasciatus female was positive for SLEV, with a minimum infection rate (MIR) of 0.29 per 1000 specimens of this species. Phylogenetic analysis indicates both human and mosquito SLEV cluster, with isolates from genotype V-A obtained from animals in the Amazon region, in the state of Pará. This is the first report of SLEV molecular identification in MT.
O vírus da dengue (DENV), frequentemente envolvido em epidemias de grande proporção, e o vírus da febre amarela (YFV), responsável por surtos silvestres esporádicos, são considerados os flavivírus circulantes mais importantes no Brasil. Por este motivo, o diagnóstico laboratorial de doença febril aguda indiferenciada durante períodos epidêmicos é frequentemente direcionado para dengue e febre amarela no país, dificultando a detecção de outros arbovírus possivelmente circulantes, incluindo o vírus da encefalite de Saint Louis (SLEV), que é amplamente disperso nas Américas. O objetivo deste estudo foi investigar molecularmente a presença de 11 flavivírus no soro de 604 pacientes durante grande epidemia de dengue no estado de Mato Grosso (MT), Centro-Oeste do Brasil, entre 2011- 2012. Concomitantemente, 3.433 fêmeas de Culex spp. capturadas com aspirador de Nasci na cidade de Cuiabá, MT e alocadas em 409 pools com 1-10 mosquitos em 2013 foram testadas por multiplex seminested RT-PCR para os mesmos flavivírus. O SLEV foi detectado em três pacientes co-infectados com o DENV-4 das cidades de Cuiabá e Várzea Grande, MT. Um dos pacientes apresentava tripla co-infecção com DENV-1. Nenhum paciente referiu histórico recente de viagem ou acesso a áreas rurais/silvestres. Um pool contendo uma fêmea de Culex quinquefasciatus foi positivo para o SLEV, apresentando taxa de infecção mínima (MIR) de 0,29 por 1000 espécimes desta espécie. A análise filogenética indica que ambas as amostras formam um cluster com isolados do genótipo V-A do SLEV obtidos de animais na região amazônica do estado do Pará. Este é o primeiro relato de identificação molecular do SLEV no MT.