Seasonal population dynamics of the primary yellow fever vector Haemagogus leucocelaenus (Dyar & Shannon) (Diptera: Culicidae) is mainly influenced by temperature in the Atlantic Forest, southeast Brazil

BACKGROUND Southeast Brazil has recently experienced a Yellow Fever virus (YFV) outbreak where the mosquito Haemagogus leucocelaenus was a primary vector. Climatic factors influence the abundance of mosquito vectors and arbovirus transmission. OBJECTIVES We aimed at describing the population dynamics of Hg. leucocelaenus in a county touched by the recent YFV outbreak. METHODS Fortnightly egg collections with ovitraps were performed from November 2012 to February 2017 in a forest in Nova Iguaçu, Rio de Janeiro, Brazil. The effects of mean temperature and rainfall on the Hg. leucocelaenus population dynamics were explored. FINDINGS Hg. leucocelaenus eggs were continuously collected throughout the study, with a peak in the warmer months (December-March). The climatic variables had a time-lagged effect and four weeks before sampling was the best predictor for the positivity of ovitraps and total number of eggs collected. The probability of finding > 50% positive ovitraps increased when the mean temperature was above 24ºC. The number of Hg. leucocelaenus eggs expressively increase when the mean temperature and accumulated precipitation surpassed 27ºC and 100 mm, respectively, although the effect of rainfall was less pronounced. MAIN CONCLUSIONS Monitoring population dynamics of Hg. leucocelaenus and climatic factors in YFV risk areas, especially mean temperature, may assist in developing climate-based surveillance procedures to timely strengthening prophylaxis and control.

Experimental yellow fever virus infection in the squirrel monkey (Saimiri spp. ) I: gross anatomical and histopathological findings in organs at necropsy

BACKGROUND Non-human primates contribute to the spread of the yellow fever virus (YFV) and the establishment of transmission cycles in endemic areas. OBJECTIVE To describe the severe histopathological aspects of YFV infection, 10 squirrel monkeys were infected with YFV and blood, brain, liver, kidney, spleen, heart, lung, lymph node and stomach were collected at 1-7, 10, 20 and 30 days post-infection (dpi). METHODS Histopathological analysis and detection of the genome and viral antigens and neutralising antibodies were performed by RT-PCR, immunohistochemistry and neutralisation test, respectively. FINDINGS Only one animal died from the experimental infection. The genome and viral antigens were detected in all investigated organs (1-30 dpi) and the neutralising antibodies from seven to 30 dpi. The brain contained perivascular haemorrhage (6 dpi); in the liver, midzonal haemorrhage and lytic necrosis (6 dpi) were observed. The kidney had bleeding in the Bowman's capsule and tubular necrosis (6 dpi). Pyknotic lymphocytes were observed in the spleen (1-20 dpi), the lung had haemorrhage (2-6 dpi), in the endocardium it contained nuclear pyknosis and necrosis (2-3 dpi) and the stomach contained blood in the lumen (6 dpi). MAIN FINDINGS Squirrel monkeys reliably reproduced the responses observed in human cases of yellow fever and, therefore, constitute an excellent experimental model for studies on the pathophysiology of the disease.

Infecção natural de Haemagogus janthinomys e Haemagogus leucocelaenus pelo vírus da febre amarela no Distrito Federal, Brasil, 2007-2008 / Haemagogus janthinomys and Haemagogus leucocelaenus naturally infected with yellow fever virus in Federal District, Brazil, 2007-2008

Objetivo: investigar a infectividade natural de Haemagogus janthinomys e Haemagogus leucocelaenus pelo vírus da febre amarela em áreas com notificação de casos humanos e epizootia em primatas não humanos no Distrito Federal (DF), Brasil. Métodos:realizaram-se capturas de Culicidae utilizando capturador de Castro e puçá, no período de dezembro de 2007 a fevereiro de 2008; a identificação taxonômica e o isolamento viral foram realizados no Instituto Evandro Chagas/ Ministério da Saúde; a inoculação em camundongo e o teste de imunofluorescência indireta foram realizados para identificar o agente viral. Resultados: amostras deHg. janthinomys e Hg. leucocelaenus procedentes da Região Administrativa de São Sebastião/DF apresentaram positividade para o vírus amarílico. Conclusão: a confirmação de infectividade natural por Hg. janthinomys e Hg. leucocelaenus sugere que as áreas pesquisadas são receptivas e vulneráveis ao vírus da febre amarela, tornando imprescindível aprimorar as estratégias de sua vigilância epidemiológica no Distrito Federal.

Objective: to investigate the natural infectivity of Haemagogus janthinomys and Haemagogus leucocelaenus for yellow fever virus in areas with reported human cases and epizootics in non-human primates, in the Federal District (DF), Brazil. Methods: Culicidae specimens were captured using hand net and oral aspirator, in the period since December 2007 to February 2008; taxonomic identification and virus research were performed at the Evandro Chagas Institute/ Ministry of Health; mouse inoculation and indirect immunofluorescence tests were performed to isolate the viral agent. Results: pools of Hg. janthinomys and Hg. leucocelaenus proceeding from the Administrative Region of São Sebastião/ DF were positive for yellow fever virus. Conclusion: confirmation of natural infectivity by Hg. janthinomys and Hg. leucocelaenus suggests that the area surveyed is receptive and vulnerable to yellow fever virus; therefore, it is essential to improve the strategies for epidemiological surveillance of yellow fever in the Federal District.

Isolation of yellow fever virus (YFV) from naturally infectied Haemagogus (Conopostegus) leucocelaenus (diptera, cukicudae) in São Paulo State, Brazil, 2009 / Isolamento do vírus da Febre Amarela de mosquitos naturalmente infectados Haemagogus (Conopostegus) leucocelaenus (Diptera, Culicidae), São Paulo, Brasil, 2009

After detecting the death of Howlers monkeys (genus Alouatta) and isolation of yellow fever virus (YFV) in Buri county, São Paulo, Brazil, an entomological research study in the field was started. A YFV strain was isolated from newborn Swiss mice and cultured cells of Aedes albopictus - C6/36, from a pool of six Haemagogus (Conopostegus) leucocelaenus (Hg. leucocelaenus) mosquitoes (Dyar & Shannon) collected at the study site. Virus RNA fragment was amplified by RT-PCR and sequenced. The MCC Tree generated showed that the isolated strain is related to the South American I genotype, in a monophyletic clade containing isolates from recent 2008-2010 epidemics and epizootics in Brazil. Statistical analysis commonly used were calculated to characterize the sample in relation to diversity and dominance and indicated a pattern of dominance of one or a few species. Hg. leucocelaenus was found infected in Rio Grande do Sul State as well. In São Paulo State, this is the first detection of YFV in Hg. leucocelaenus.

Após a detecção de morte de macacos Bugios (gênero Alouatta) e isolamento do vírus da Febre Amarela (YFV) no município de Buri, Estado de São Paulo, Brasil, foi iniciada uma investigação entomológica em campo. Uma cepa de YFV foi isolada em camundongos recém-nascidos e cultura de células de Aedes albopictus - C6/36, a partir de um lote de seis mosquitos Haemagogus (Conopostegus) leucocelaenus (Hg leucocelaenus) Dyar & Shannon coletados no local de estudo. RNA do vírus foi amplificado por RT-PCR e seqüenciado. A topologia gerada indica que a cepa isolada está relacionada ao genótipo South American I, em clado monofilético englobando isolados recentes de epidemias e epizootias entre 2008 e 2009. Análises estatísticas geralmente usadas caracterizaram a amostra em relação à diversidade e dominância, indicando dominância relativa de uma ou poucas espécies. Hg. leucocelaenus foi detectado infectado também no Rio Grande do Sul. No Estado de São Paulo trata-se da primeira detecção do YFV em Hg leucocelaenus.

Epizootias em primatas não humanos durante reemergência do vírus da febre amarela no Brasil, 2007 a 2009 / Epizootics in nonhuman primates during reemergence of yellow fever virus in Brazil, 2007 to 2009

Objetivo: descrever e analisar a mudança do perfil epidemiológico da febre amarela silvestre no Brasil – que passa a ocorrer fora da Amazônia – a partir de 1999, quando a detecção do vírus em primatas permitiu a aplicação oportuna de novas medidas de vigilância. Metodologia: este estudo faz uma análise descritiva das epizootias em primatas notificadas ao Ministério da Saúde (MS) entre 2007 e 2009; para captação dos dados, foram utilizadas a Ficha de Notificação de Epizootia do Sistema de Informação de Agravos de Notificação (Sinan) e planilha de notificação diária. Resultados: No período, foram notificadas 1.971 epizootias em primatas, sendo 73 no ano de 2007, 1.050 em 2008 e 848 em 2009; essas epizootias ocorreram em 520 municípios de 19 estados; do total de epizootias notificadas, 209 (10,6 por cento) foram confirmadas para febre amarela. Conclusão: as informações aqui discutidas são fundamentais para o aperfeiçoamento da vigilância e a consolidação da notificação de epizootias em primatas, como instrumento de prevenção de casos humanos da doença.

Objective: to describe and analyze the change in the epidemiological profile of sylvatic yellow fever – whose cases began to occur outside the Amazon region, in Brazil – from 1999, when the detection of the virus in primates has led to the timely implementation of new surveillance measures. Methodology: this study is a descriptive analysis of epizootics in primates notified to the Ministry of Health between 2007 and 2009; data were captured using the Epizootic Notification Form of the Brazilian Information System for Notifiable Diseases (Sinan) and daily reporting spreadsheet. Results: from 1,971 epizootics reported during the period, 73 occurred in 2007, 1,050 in 2008, and 848 in 2009; and 209 (10.6 per cent) were confirmed for yellow fever; these epizootics have been registered in 520 municipalities of 19 states. Conclusion: the information discussed herein is fundamental for improving the surveillance and consolidating the notification of epizootics in primates, as a tool for preventing human cases of the disease.

Febre amarela / Yellow fever

A febre amarela é doenca infecciosa näo-contagiosa causada por um arbovírus mantido em ciclos silvestres em que macacos atuam como hospedeiros amplificadores e mosquitos dos gêneros Aedes na Africa, e Haemagogus e Sabethes na América, säo os transmissores. Cerca de 90 por cento dos casos da doença apresentam-se com formas clínicas benignas que evoluem para a cura, enquanto 10 por cento desenvolvem quadros dramáticos com mortalidade em torno de 50 por cento. O problema mostra-se mais grave em Africa onde ainda há casos urbanos. Nas Américas, no período de 1970-2001, descreveram-se 4.543 casos. Os países que mais diagnosticaram a doença foram o Peru (51,5 por cento), a Bolívia (20,1 por cento) e o Brasil (18,7 por cento). Os métodos diagnósticos utilizados incluem a sorologia (IgM), isolamento viral, imunohistoquímica e RT-PCR. A zoonose näo pode ser erradicada, mas, a doença humana é prevenível mediante a vacinaçäo com a amostra 17D do vírus amarílico. A OMS recomenda nova vacinaçäo a cada 10 anos. Neste artigo säo revistos os principais conceitos da doença e os casos de mortes associados à vacina

Molecular analysis of yellow fever virus 17DD vaccine strain

The Oswaldo Cruz Foundation produces most of the yellow fever (YF) vaccine prepared world wide. As part of a broader approach to determine the genetic variability in YF l7D seeds and vaccines and its relevance to viral attenuation the 17DD virus was purifed directly from chick embryo homogenates which is the source of virus used for vaccination of millions of people in Brazil and other countries for half a century. Neutralization and hemagglutination tests showed that the purified virus is similar to the original stock. Furthermore, radioimmune precipitation of 35S-methionine-labeled viral proteins using mouse hyperimmune ascitic fluid revealed identical patterns for the purified 17DD virus and the YF l7D-204 strain except for the 17DD E protein which migrated slower on SDS-PAGE. This difference is likely to be due to N-linked glycosylation. Finally, comparison by northern blot nybridization of virion RNAs of purified 17DD with two other strains of YF virus only fenome-sized molecules for all three viruses. These observations suggest that vaccine phenotype is primarily associated with the accumulation of mutations