Vigilância para Febre do Nilo Ocidental (FNO) em aves de subsistência localizadas em sítio de aves migratórias do Complexo estuarino-lagunar de Ilha Comprida e Iguape/SP / Surveillance for West Nile Fever in backyard chickens located in a migratory bird site of the estuarine-lagoon complex of Ilha Comprida and Iguape/SP

A Febre do Nilo Ocidental (FNO), é uma arbovirose emergente, zoonótica, causada pelo Vírus do Nilo Ocidental (VNO), arbovírus da família Flaviviridae, do gênero Flavivírus, com ampla distribuição mundial. Vírus foi isolado pela primeira vez em 1937, em uma paciente febril, na província de West Nile, em Uganda, e documentado em 1951 em Israel, havendo registros de ocorrência em aves, equinos e no homem. Nas Américas, o primeiro surto ocorreu em 1999 na cidade de Nova York (EUA), com mortalidade de milhares de aves silvestres e 121 pessoas, um marco histórico para a doença e na construção das bases de vigilância do vírus. A doença se espalhou pelas Américas, com a primeira evidência na América do Sul, em equinos na Colômbia, em 2005. No Brasil, o primeiro registro ocorreu no Mato Grosso do Sul em equinos, no ano de 2010, e o primeiro caso humano em 2014, no Piauí, sendo comprovada a circulação viral em aves silvestres, galinhas e equinos nos últimos dez anos. A transmissão ocorre pela picada do mosquito infectado do Gênero Culex, mantendo um ciclo enzoótico de transmissão mosquito-ave silvestre-mosquito, sendo que as aves silvestres são hospedeiros primários, e destacam - se na disseminação viral entre as Américas, através de deslocamentos migratórios, sem haver elucidação dos mecanismos de dispersão. A infecção de galinhas, equinos e do homem é acidental, por apresentarem uma viremia rápida e curta, tornando os elos finais da cadeia de transmissão ou sentinelas, para a doença. A FNO é aguda, subclínica ou com quadro febril, que pode ocasionar síndrome neurológica grave em até 10% dos casos, com recuperação ou óbito em 1% dos casos, não havendo tratamento ou vacina disponível no Brasil. A FNO é de Notificação Obrigatória - IN n° 50/2013 - MAPA. Características inerentes à galinhas, de suscetibilidade à infecção, resistência à doença e alta sensibilidade à testes de detecção viral, tornam esta espécie um modelo de sentinela para o VNO, em sítios migratórios, aonde coexistem aves silvestres, culicídeos e criações de fundo de quintal que ficam vulneráveis à infecção, demonstrando a importância da vigilância para a FNO no Brasil. O presente estudo teve como objetivos a revisão de literatura sobre a FNO e o estudo de circulação viral em aves de fundo de quintal de 17 propriedades do entorno do sítio de aves migratórias do complexo estuarino-lagunar de Ilha Comprida e Iguape/SP, com colheita de amostras de sangue em 113 galinhas, para a detecção do VNO e outros flavivírus pela técnica RT-PCR. Não houve a detecção de atividade viral nas amostras analisadas. Contudo, a ações de vigilância para o VNO e o monitoramento contínuo dos sítios migratórios de aves devem ser rotineiros, para evitar a introdução e disseminação da doença, destacando - se as notificações de sinais clínicos neurológicos ou mortalidade em aves.

West Nile Fever (WNF) is an emerging zoonotic arbovirus caused by the West Nile Virus (WNV), a flavivirus of the Flaviviridae family with worldwide distribution. The virus was first isolated in 1937 from a febrile patient in the West Nile province of Uganda and documented in 1951 in Israel. WNV has been reported to occur in birds, horses, and humans. The first outbreak in the Americas occurred in 1999 in New York City, with thousands of wild birds dying and 121 human deaths. The disease has since spread throughout the Americas, with the first evidence in South America occurring in horses in Colombia in 2005. In Brazil, the first WNV record occurred in horses in Mato Grosso do Sul in 2010, and the first human case was reported in 2014 in Piauí. WNV circulation has been confirmed in wild birds, chickens, and horses in the past ten years. The virus is transmitted by infected Culex mosquitoes, maintaining an enzootic cycle of mosquito-wild bird-mosquito transmission. Wild birds are the primary hosts and play a significant role in viral dissemination across the Americas through migratory movements, with no elucidation of the dispersal mechanisms. Chickens, horses, and humans are accidental hosts due to their rapid and short viremia, making them the final links in the transmission chain or sentinels for the disease. WNF is acute or subclinical, with fever that can lead to severe neurological syndromes in up to 10% of cases, with recovery or death in 1% of cases. There is no treatment or vaccine available for WNF in Brazil. WNF is a mandatory reportable disease according to IN n° 50/2013 - MAPA. The susceptibility of chickens to infection, resistance to disease, and high sensitivity to viral detection tests make this species a sentinel model for WNV in migratory sites where wild birds, culicids, and backyard farming coexist and are vulnerable to infection. Therefore, continuous surveillance for WNF in Brazil is crucial. This study aimed to review the literature on WNF and to investigate viral circulation in backyard chickens in 17 properties around the migratory bird site of the estuarine-lagoon complex of Ilha Comprida and Iguape/SP, with blood samples collected from 113 chickens for WNV and other flavivirus detection by RT-PCR. No viral activity was detected in the analyzed samples. However, surveillance for WNV and continuous monitoring of migratory bird sites should be routine to prevent the introduction and spread of the disease, with notifications of clinical neurological signs or mortality in birds.

West nile virus infections are here! are we prepared to face another flavivirus epidemic?

Abstract Emerging arthropod-borne viruses (arboviruses), such as chikungunya and Zika viruses, are a major threat to public health in countries like Brazil where biodiversity is high and medical care is sometimes precarious. West Nile fever is a disease caused by the West Nile Virus (WNV), an RNA virus belonging to the Flaviviridae family. It is transmitted by infected mosquitoes to numerous animals like birds, reptiles and mammals, including human and non-human primates. In the last decade, the number of reported cases of WNV infection in humans and animals has increased in the Americas. Circulation of WNV in forests and rural areas in Brazil has been detected based on serological surveys and, in 2014, the first case of West Nile fever was confirmed in a patient from Piauí State. In 2018, the virus was isolated for the first time from a horse from a rural area in the state of Espírito Santo presenting with a neurological disorder; this raises the possibility that other cases of WNV encephalitis may have occurred without clinical recognition and without laboratory diagnosis by specific assays. The imminent WNV outbreak poses a challenge for Brazilian clinicians and researchers. In this review, we summarize the basic biological and ecological characteristics of this virus and the clinical presentation and treatment of febrile illnesses caused by WNV. We also discuss the epidemiological aspects, prophylaxis of WNV infections, and monitoring strategies that could be applied in the possibility of a WNV outbreak in Brazil.

South-South Cooperation: Brazilian experiences in South America and Africa / Cooperação Sul-Sul: experiências brasileiras na América do Sul e na África

Over recent years Brazil has played an increasingly active role internationally, the result of its model of integration and its foreign policy directives. The health sector is a valuable and strategic area for Brazilian technical cooperation to achieve various objectives, including its development goals. This article describes the main directives of Brazilian foreign policy, conceptually defining and characterizing South-South Cooperation, illustrated through an analysis of two Brazilian technical cooperation initiatives in healthcare: one in South America, the other in Africa. The study concludes that, irrespective of the interests and power asymmetries existing in South-South Cooperation, the objectives of this cooperation were achieved through the technical work.

Nos últimos anos, o Brasil foi ativo no âmbito internacional, tanto por seu modelo de inserção como pelas diretrizes de política externa. O setor saúde é uma ferramenta valiosa e estratégica utilizada pela cooperação técnica brasileira para lograr seus objetivos de desenvolvimento. Este artigo descreve as principais diretrizes de política externa brasileira, conceitua e caracteriza a Cooperação Sul-Sul, ilustrada mediante análise de duas iniciativas de cooperação técnica em saúde do Brasil: na América do Sul e na África. O estudo conclui que, independentemente dos interesses e das assimetrias de poder que existem na Cooperação Sul-Sul, os objetivos dessa cooperação foram alcançados por meio do trabalho técnico.

Serological detection of West Nile virus in horses and chicken from Pantanal, Brazil

In an effort to detect West Nile virus (WNV) in Brazil, we sampled serum from horses and chickens from the Pantanal region of the state of Mato Grosso and tested for flavivirus-reactive antibodies by blocking ELISA. The positive samples were further confirmed for serological evidence of WNV infection in three (8%) of the 38 horses and one (3.2%) of the 31 chickens using an 80% plaque-reduction neutralisation test (PRNT80). These results provide evidence of the circulation of WNV in chickens and horses in Pantanal.

Fiebre por virus del Nilo Occidental ¿Otra patología emergente relacionada con el cambio climático? / West Nile fever virus. Another emerging disease linked to climate change?

La Fiebre del Nilo Occidental (FNO) es producida por un arbovirus (familia Flaviviridae, género flavivirus) y transmitida por mosquitos Culex. En los '50 se detectó en Israel, Egipto e India, y en 1974 en Sudáfrica. Luego en Argelia (1994), Rumania (1996), República Checa (1997), Rusia (1999) y en EE.UU. (1999), notificados al CDC desde entonces, 24.716 casos con 983 fallecidos. En el 2012 lleva afectando a 3.545 personas con 147 fallecidos. En la Unión Europea (23/8/2012) se notificaron 91 casos (37 confirmados). En Grecia los casos han ascendido a 86. En países vecinos a la UE se notificaron 143 casos. El virus se ha diseminado a Canadá, América Central y el Caribe, afectando las Islas Caimán, Jamaica, República Dominicana, México, Puerto Rico y Cuba. Argentina, sin antecedentes hasta marzo de 2006, confirmó en Córdoba la infección en un hombre y otros 3 en el Chaco. En abril de ese año se confirmó la muerte de 2 caballos en SA de Areco (Buenos Aires), 1 en Entre Ríos y en el 2010 otro equino en Córdoba. Las aves infectadas por hembras de Culex migran a Centroamérica y América del Sur, transmitiendo el virus a especies de vertebrados (mascotas; animales de granja -caballos- y el hombre). El virus puede infectar a otros seres humanos por transfusiones, trasplantes de órganos, etc. No se transmite de persona a persona. Clínicamente se presenta con un cuadro febril o con compromiso neurológico. Los factores de riesgo son variados (HIV/SIDA, trasplante de órganos, quimioterapia, embarazo, etc). La prevención es la lucha contra el mosquito. La fumigación es un recurso útil. Las aguas estancadas donde se reproducen los mosquitos deben drenarse. Los cambios climáticos ocasionan importantes consecuencias para la salud humana con multiplicación de vectores infectantes. Los EE.UU. han tenido este año un invierno suave y un verano caluroso...

The FNO is caused by an arbovirus (family Flaviviridae, genus Flavivirus) and transmitted by Culex mosquitoes. In the 50 was detected in Israel, Egypt and India and in South Africa in 1974. Then in Algeria (1994), Romania (1996), Czech Republic (1997), Russia (1999) and the USA (1999), reported to the CDC since then, 24,716 cases with 983 deaths. In 2012 carries affecting 3.545 people with 147 deaths. In the European Union (23/08/2012) 91 cases were reported (37 confirmed). In Greece’s case amounted to 86. In neighboring countries the UE 143 cases were reported. The virus has spread to Canada, Central America and Caribbean, affecting the Cayman Islands, Jamaica, Dominican Republic, Mexico, Puerto Rico and Cuba. Argentina shows no background until March 2006, confirmed in Cordoba infection in a man and another three in Chaco. In April of that year confirmed the death of two horses in San Antonio de Areco (Buenos Aires), one in Entre Ríos and in 2010 another horse in Cordoba. Birds infected Culex females migrate to Central and South America, transmitting the virus to vertebrate species (pets, farm animals, horses, and man). The virus can infect humans for transfusions, organ transplants, etc. It is not transmitted from person to person. Clinically presents with a fever or neurological compromise. Risk factors are varied (HIV / AIDS, organ transplants, chemotherapy, pregnancy, etc). Prevention is the fight against the mosquito. Fumigation is a useful resource. The stagnant water where mosquitoes breed, should be drained. Climate changes cause significant consequences to human health, with infective vector multiplication. The US has had this year a mild winter and a hot summer. Mankind will become aware of the damage that involves not observe regulatory mitigation measures and environmental pollution. Only a commitment to protecting the environment is everyone’s future hope. We will address other emerging pathology related to climate change...

Serological detection of St. Louis encephalitis virus and West Nile virus in equines from Santa Fe, Argentina

St. Louis encephalitis virus (SLEV) and West Nile virus (WNV) present ecological and antigenic similarities and are responsible for serious human diseases. In addition, WNV is a significant pathogen in terms of equine health. The purpose of our study was to analyse the seroprevalence of SLEV and WNV in equine sera collected in Santa Fe Province, Argentina. The seroprevalence determined using the plaque reduction neutralisation test was 12.2% for SLEV, 16.2% for WNV and 48.6% for a combination of both viruses. These results provide evidence of the co-circulation of SLEV and WNV in equines in Santa Fe.

Seroconversion for west Nile and St. Louis encephalitis viruses among sentinel horses in Colombia

We prospectively sampled flavivirus-naïve horses in northern Colombia to detect West Nile virus (WNV) and St. Louis encephalitis virus (SLEV) seroconversion events, which would indicate the current circulation of these viruses. Overall, 331 (34.1 percent) of the 971 horses screened were positive for past infection with flaviviruses upon initial sampling in July 2006. During the 12-month study from July 2006-June 2007, 33 WNV seroconversions and 14 SLEV seroconversions were detected, most of which occurred in the department of Bolivar. The seroconversion rates of horses in Bolivar for the period of March-June 2007 reached 12.4 percent for WNV and 6.7 percent for SLEV. These results comprise the first serologic evidence of SLEV circulation in Colombia. None of the horses sampled developed symptoms of encephalitis within three years of initial sampling. Using seroconversions in sentinel horses, we demonstrated an active circulation of WNV and SLEV in northern Colombia, particularly in the department of Bolivar. The absence of WNV-attributed equine or human disease in Colombia and elsewhere in the Caribbean Basin remains a topic of debate and speculation.

Estratificación epidemiológica del riesgo de las enfermedades emergentes y reemergentes por municipios, Matanzas, 2002-2006 / Epidemiologic stratification of the emergent and re-emergent diseases risk per municipalities, Matanzas, 2002-2006

Las enfermedades emergentes y reemergentes constituyen un problema de salud que preocupa a los gobiernos y a las autoridades de Salud Pública por los efectos económicos y sociales que pueden ocasionar. Se realizó un estudio observacional descriptivo en la población de la provincia de Matanzas, distribuida geográficamente en sus municipios, para estratificar el riesgo para las enfermedades emergentes y reemergentes en el período 2002-2006. Se seleccionaron las enfermedades a estudiar y los indicadores por un grupo de expertos: para la tuberculosis y el VIH/sida fueron la tasa de prevalencia y de letalidad, para el dengue y el paludismo los casos importados y el índice de infestación, para la influenza aviar y la fiebre del Oeste del Nilo Occidental el asentamiento de aves migratorias, el arribo de viajeros de áreas endémicas y para esta última también el índice de infestación. Los datos fueron obtenidos de las tarjetas de enfermedades de declaración obligatoria y certificados de defunción de la Dirección Provincial de Salud y del Centro Provincial de Higiene, Epidemiología y Microbiología, así como del sistema de vigilancia vectorial de la Unidad Provincial de Vectores y de aves migratorias de la Dirección Provincial de Medicina Veterinaria y el CITMA. Obteniéndose como resultado que Jagüey Grande, Matanzas y Varadero fueron los municipios de mayor riesgo, constituyendo una herramienta de trabajo para los cuadros a diferentes niveles del sistema, ya que brinda un grupo de elementos con base científica para reorientar la vigilancia de estas enfermedades, organizar los servicios de salud e intervenir oportunamente.

The emergent and re-emergent diseases are a health problem worrying the governments and the public health authorities because of the economic and social effects they can have. We carried out an observational descriptive study in the population of the province of Matanzas, geographically distributed in municipalities, to stratify the risk of the emergent and re-emergent diseases in the period 2002-2006. We selected the diseases and the indicators to study for a group of experts: for the tuberculosis and HIV/AIDS were choose the indicators prevalence rate and lethality; for the dengue and malaria, the imported cases and the infestation index; for the chicken influenza and the Western Nile fever, the population of the migratory birds, the arrival of passengers from endemic areas, and for the last one the infestation index. The data were obtained from the forms of the diseases of obligatory declaration and from the decease certificates in the Provincial Health Direction and the Provincial Center of Hygiene, Epidemiology and Microbiology, and also from the system of vectorial surveillance of the Provincial Unit of Vectors. The data about the migratory birds were gathered in the Provincial Directions of Veterinary Medicine and of Sciences, Technology and Environment. The municipalities of Jagüey Grande, Matanzas and Varadero were the ones with the highest risks. This is a working tool for the persons in charge in the different levels of the system giving elements on a scientific basement to re-orientate the surveillance of these diseases, organize the health care services and the intervention on time.

Estudio serológico en localidades cubanas con infecciones confirmadas al virus del Nilo Occidental / Serological study carried out in Cuban localities where confirmed Western Nile virus infection is present

Introducción: las primeras infecciones por el virus del Nilo Occidental en Cuba se reportaron en 2004. Objetivo: monitorear y conocer la prevalencia del virus del Nilo Occidental en áreas con casos confirmados de este. Métodos: el estudio se llevó a cabo en la municipalidad de Jatibonico y en la ciudad de Sancti Spiritus. Un total de 14 personas, 8 caballos y 41 aves se estudiaron para la detección de anticuerpos a flavivirus y específicos al virus del Nilo Occidental. Resultados: se confirmó la presencia de anticuerpos específicos a virus del Nilo Occidental en 4 muestras de suero de aves y 4 de caballos. Una persona se confirmó como 1 caso de infección por virus del Nilo Occidental asintomático. Conclusiones: la presencia de anticuerpos específicos al virus del Nilo Occidental en aves residentes, caballos y humanos en áreas con casos confirmados demuestran el establecimiento de un ciclo de amplificación local establecido en Cuba antes de este estudio.

Introduction: First infected cases caused by West Nile virus were reported in Cuba in 2004. Objective: to monitor and learn about the prevalence of the West Nile virus in those areas with confirmed cases. Methods: the study was conducted in Jatibonico municipality and in the city of Sancti Spiritus. A total number of 14 persons, 8 horses and 41 birds were researched to detect antibodies to flavivirus and specific antibodies to West Nile virus. Results: the presence of specific antibodies to West Nile virus was confirmed in 4 samples of sera from birds and in 4 from horses. One person was confirmed as one case of asymptomatic West Nile virus infection. Conclusions: the presence of specific antibodies to West Nile virus in birds, horses and persons residing in areas where there are confirmed cases showed that a local amplification cycle had been established in Cuba before this study.

O vírus do Nilo Ocidental: [revisão] / West Nile virus: [review]

O vírus do Nilo Ocidental (WNV) é um flavivírus que se mantém na natureza em ciclos alternados de infecção, em pássaros e mosquitos hematófagos, principalmente do gênero Culex. A infecção natural já foi demonstrada em mais de 200 espécies de aves, sendo que a susceptibilidade à infecção e à doença varia amplamente. Os corvídeos e os passeriformes são particularmente susceptíveis, desenvolvendo altos níveis de viremia e também elevada mortalidade. Ocasionalmente, a infecção pode ser transmitida para mamíferos pela picada de mosquitos que realizaram o repasto sangüíneo em aves virêmicas. Os humanos e os eqüinos estão entre os mamíferos mais susceptíveis e freqüentemente desenvolvem um quadro febril, que pode ser acompanhado de infecção neurológica e meningoencefalite fatal. A infecção pelo WNV, inicialmente identificada em Uganda (1937), durante décadas ficou restrita ao Norte da África, ao Oeste da Ásia, ao Oriente Médio e à Europa Mediterrânea, com relatos de casos isolados ou pequenos surtos de doença em humanos e eqüinos. Em 1999, o vírus foi introduzido em Nova Iorque, nos Estados Unidos, onde causou mortalidade de milhares de aves e infectou centenas de pessoas, levando 21 a óbito. A partir de então, a infecção se disseminou por praticamente todos os Estados norte-americanos, causando infecção e/ou doença em mais de 27 mil pessoas (1100 mortes), eqüinos (mais de 25.000 casos) e provocando mortalidade e redução da população de algumas espécies de aves silvestres. Evidências da infecção têm sido progressivamente detectadas em várias espécies animais no México, na América Central, no Caribe e no Norte da América do Sul, indicando a sua disseminação na direção sul. O WNV foi identificado como o agente de meningoencefalite fatal em três eqüinos na Argentina (2006), onde parece estar presente em pássaros nativos pelo menos desde 2005. Pesquisadores e autoridades sanitárias brasileiras da área humana e animal temem que a infecção seja introduzida...

West Nile virus (WNV) is a Flavivirus maintained in nature through alternate cycles of infection in wild birds and haematophagus mosquitoes, mainly Culex sp. Natural infection by WNV has been demonstrated in more than 200 bird species, which present variable susceptibility to infection and disease. Corvids and passeriformes are particularly susceptible and develop high levels of viremia and mortality. Occasionally, the virus may be transmitted to mammals by mosquitoes feeding previously on viremic birds. Human and horses are highly susceptible to WNV infection and often develop fever, which may be followed by neurological infection and fatal meningoencephalitis. Originally identified in Uganda (1937), WNV infection remained for decades restricted to North Africa, East Asia, Middle East and Mediterranean Europe. In these areas, isolated cases of human and horse disease, or small outbreaks were occasionally reported. In 1999, the virus was introduced in New York, USA, where it caused mortality in thousands of wild and captive birds and infected hundreds of people, killing 21. Thereafter, the infection rapidly spread out over the US territory, causing thousands of human infections (more than 27.000 - around 1100 deaths) and equine infections (more than 25.000 cases). WNV infection has also been detected in wild and domestic birds, horses and other mammals across Mexico, Central America and the Caribbean, and northern South America, indicating its dissemination southwards. In 2006, WNV was first identified as the agent of fatal neurological disease in three horses in Argentina, where it has been shown to be circulating in wild birds at least since 2005. Brazilian's human and animal health authorities are concerned with a possible introduction of the virus in the country, where it would find ideal ecological conditions for transmission and spread. This article presents a brief review on the main epidemiological and clinico-pathological...

Prevalencia de infección por el virus del Nilo Occidental en dos zoológicos del estado de Tabasco / Prevalence of West Nile Virus infection in animals from two state zoos Tabasco

OBJETIVO: Determinar la prevalencia de infección por el virus del Nilo Occidental (VNO) en animales, mosquitos y personal que labora en dos zoológicos del estado de Tabasco, en México. MATERIAL Y MÉTODOS: Con la utilización de ELISA de bloqueo se detectaron anticuerpos en sueros de animales: se buscó un fragmento del genoma del VNO por RT-PCR en el suero de animales, empleados y mosquitos. RESULTADOS: En el zoológico "La Venta" se encontró una seroprevalencia de 25.67 por ciento (19/74) en aves y de 85.71 por ciento (6/7) en reptiles. En el zoológico "Yum-Ká", 31.25 por ciento (50/160) de las aves y 34.48 por ciento (16/29,) de los mamíferos, tuvieron anticuerpos contra el VNO. En un grupo de mosquitos (Culex quinquefasciatus) se detectó el genoma del virus. CONCLUSIONES: La detección de anticuerpos contra el VNO en animales de ambos zoológicos y del genoma viral en mosquitos demuestra la presencia del virus, lo cual representa un riesgo potencial de infección para animales y humanos.

OBJECTIVE: To determine the prevalence of West Nile Virus (WNV) infection in animals, mosquitoes and employees from two zoos of Tabasco state, Mexico. MATERIAL AND METHODS: WNV antibodies were detected by blocking ELISA in serum samples from animals. Viral RNA was detected by RT-PCR from mosquitoes and serum samples from employees at "Yum-Ká" zoo. RESULTS: Seroprevalence in birds was 25.65 percent (19/74) and 85 percent (6/7) in reptiles from "La Venta" zoo. Thirty-one percent of birds (50/160) and 34.48 percent mammals (16/29) at the "Yum-Ká" zoo, were seropositive. All human serum samples from Yum-ká zoo were negative by RT-PCR. A pool of mosquitoes (Culex quinquefasciatus) was positive for WNV. CONCLUSIONS: The presence of WNV antibodies in animals from both zoos and the detection of viral genome in mosquitoes demonstrate the presence of WNV in this region and indicates a potential risk of infection in animals and humans.

A quantitative risk assessment of West Nile virus introduction into Barbados / Una evaluación del riesgo cuantitativo de la introducción del virus del Nilo Occidental en Barbados

OBJECTIVE: To present a quantitative risk assessment of West Nile (WNV) virus introduction into Barbados, West Indies. DESIGN AND METHODS: Three possible modes were considered: a) WNV infected mosquitoes via air transport, by city of departure, b) WNV infected mosquitoes via marine transport and c) viraemic migratory, birds. We estimated the number of WNV infected migratory birds as the product of the proportion of migratory birds infected and the number of migratory birds entering Barbados in three taxonomic groups. We further estimated the number of days these birds would be infectious as: [formula: see text]. We then estimated the number (#) of infectious mosquito-days for mosquitoes entering Barbados via air transport as: # infected mosquitoes = (total flights per week/city) x (duration of WNV season) x (number of Culex mosquitoes aboard each flight) x (Culex mosquito WNV infection prevalence) x (vector competence index) x (days infectious). The number of infected mosquitoes entering Barbados via marine transport was estimated using a similar expression as for air transport, except that the number of airplanes and mosquitoes/airplane were substituted with the # of sea containers during a 22-week mosquito season and # of mosquitoes/container. RESULTS: Migratory birds (approximately 69-101 infected birds/year) were associated with the highest introductory risk followed by mode (a) (approximately 2 infected mosquitoes/year) and mode (b) (0. 004 infected mosquitoes/year). CONCLUSIONS: Migratory birds and mosquitoes via air are imminent threats for virus introduction. Impending co-circulation of West Nile virus and four strains of dengue virus may present new challenges for public health.

OBJETIVO: Presentar una valoración del riesgo cuantitativa de la introducción del Virus del Nilo Occidental (VNO) en Barbados, West Indies. MÉTODOS E DISEÑO: Se consideraron tres posibles modos: a) mosquitos infectados con el VNO vía transporte aéreo, por ciudad de salida, b) mosquitos infectados con el VNO vía transporte marítimo, y c) aves migratorias virémicas. Calculamos el número de aves migratorias infectadas con el VNO como el producto de la proporción de aves migratorias infectadas por el número de aves migratorias que entran a Barbados en tres grupos taxonómicos. Luego calculamos el número de días en que estas aves serían infecciosas, de la forma siguiente:[fórmula: ver en el texto].Calculamos entonces el número de días-mosquito infeccioso para los mosquitos que entran en Barbados mediante transporte aéreo, como sigue: # mosquitos infectados = (vuelos totales por semana/ciudad) x (duración de la estación del VNO) x (número de mosquitos Culex a bordo de cada vuelo) x (prevalencia de infección con VNO por mosquito Culex) x (índice de competencia del vector) x (días infecciosos). El número de mosquitos infectados que entraron a Barbados por vía del transporte marítimo fue calculado usando una fórmula similar a la usada en relación con el transporte aéreo, excepto que el número de aeroplanos y mosquitos/ aeroplanos fueron sustituidos con el # de contenedores marítimos durante una temporada de mosquitos de 22 semanas y el # de mosquitos/contenedor RESULTADOS: Las aves migratorias ~ (69-101 aves infectadas/años) estuvieron asociadas con el riesgo de introducción más alto seguido del modo (a) (~2 mosquitos infectados/año), y finalmente el modo (b) (0.004 mosquitos infectados/año). CONCLUSIONES: Las aves migratorias y los mosquitos por vía aérea representan una amenaza inminente de introducción de virus. La co-circulación inminente del Virus del Nilo Occidental y cuatro cepas de virus de dengue pueden presentar nuevos desafíos a la salud pública.

El virus del Oeste del Nilo: una realidad en México / West Nile virus: a reality in Mexico

El virus del Oeste del Nilo (VON) es un virus ARN perteneciente a la familia Flaviviridae del género Flavivirus que causa infección en aves, equinos y humanos. La infección por VON es transmitida por el mosquito Culex sp. El ciclo de vida del virus incluye a los mosquitos como vectores y a las aves como huéspedes naturales. El virus mantiene un ciclo de transmisión mosquito–ave-mosquito. Los seres humanos son huéspedes accidentales. Se han reportado epidemias en Rumania, Nueva York e Israel. Mediante el programa de vigilancia epidemiológica en nuestro país, se han reportado 90 muestras positivas en 1,223 casos estudiados en aves hasta el 15 de Septiembre del 2005. La enfermedad por el VON se presenta con fiebre, malestar general, anorexia, nausea, vómito, cefalea, mialgia, erupción cutánea y linfadenopatía. La principal entidad clínica descrita es la encefalitis y la parálisis flácida. A mayor edad, es mayor el riesgo de enfermedad neurológica y muerte. Los métodos diagnósticos incluyen determinación de anticuerpos IgM e IgG en suero y/o liquido cerebroespinal. No existe tratamiento antiviral para la infección por VON. Algunas terapias que se han utilizado incluyen interferón α2b e inmunoglobulina específica contra VON. La prevención juega un papel crucial.

West Nile virus (WNV) is a RNA virus of the Flaviridae, genus flavivirus family. It is a neuropathogenic virus causing disease in birds, horses and humans. WNVis transmitted by the vector mosquito Culex sp. The virus life 's cycle includes mosquitoes as vectors and birds as natural hosts. Humans are accidental hosts. Since the introduction of the Epidemiological Surveillance Program at the Ministry ofHealth. we have documented 90 positive test results among birds out of 1,223 cases studied in Mexico as of September IS. 2005. The incubation period in humans after a mosquito bite ranges from 3 to 14 days. Disease is characterized by early onset fever, general malaise, decreased appetite, nausea, vomiting, headaches, myalgias, enlarged lymph nodes andrash. Neurological manifestations include encephalitis andflaccid paralysis, which are present in less than 1% of subjects infected with WNV. Older patients display more adverse outcomes including death. The diagnosis is made by the determination of specific IgM and JgG antibodies in serum and/or cerebrospinal fluid. There is no antiviral treatment to date against WNV but interferon ?2b, and WNVspec4ic-immunoglobulin have been used Prevention is therefore the key to control the infection.

Virus del oeste del Nilo: ecología y epidemiología de un patógeno emergente en Colombia / West Nile virus; ecology and epidemiology of an emerging pathogen in Colombia

El virus del oeste del Nilo (VON) es mantenido en la naturaleza en un ciclo enzoótico ave-mosquito-ave. Los principales vectores son los mosquitos del genero Culex. Las aves son los huéspedes amplificadores primarios. Humanos y caballos son huéspedes incidentales finales. En humanos las infecciones por VON se presentan como enfermedad febril autolimitada. En los casos de enfermedad neurológica se puede presentar encefalitis, meningitis o meningoencefalitis, con mayor incidencia y mortalidad por encefalitis en personas de mayor edad y pacientes inmunocomprometidos. Se han reportado brotes en Africa, Medio Oriente, Europa y Asia. El virus apareció por primera vez en Estados Unidos en 1999 y se ha documentado su circulación en México, Islas Caimán, Jamaica, Republica Dominicana, Martinica, Guadalupe, Cuba, Puerto Rico, El Salvador y recientemente Colombia. La importancia en salud pública de VON si es introducido en áreas de Centro y Sur América dependerá del resultado de la interacción de múltiples factores. Colombia reúne las condiciones que favorecen su entrada y desarrollo. Se pueden postular dos hipótesis: el virus podría llegar a ser enzoótico y endémico y causar limitada enfermedad humana, o podría llegar a ser epidémico y causar brotes anuales que afecten humanos y animales. Esto dependerá de la susceptibilidad de las especies aviares colombianas al virus por las diferencias en su biología, y a las variaciones geográficas intraespecificas en la competencia de las diferentes especies de mosquito y los efectos de las condiciones medioambientales sobre su habilidad para transmitir el virus, y estos factores son determinantes en el ciclo de amplificación primario.

West Nile virus activity in Latin America and the Caribbean

OBJETIVOS: El virus del Nilo occidental (VNO, familia Flaviviridae, género Flavivirus) se ha propagado rápidamente por toda la cuenca del Caribe desde que se detectó por primera vez en 2001. En este informe se resumen nuestros conocimientos actuales acerca de la transmisión del VNO en zonas tropicales del continente americano. MÉTODOS: Revisamos todo lo que se ha publicado sobre el tema y consultamos a autoridades de salud clave para obtener datos inéditos. RESULTADOS: Las infecciones por el virus del Nilo occidental aparecieron por primera vez en seres humanos residentes de las Islas Caimán y de los Cayos de la Florida en 2001, y en pájaros de aspecto sano de los cuales se obtuvieron muestras a principios de 2002. En 2002 se encontraron pruebas serológicas de infección por el VNO en caballos, pollos y aves de corral no estabuladas oriundas de Guadalupe, la República Dominicana y la parte oriental de México. En 2003, el VNO se diseminó dentro de México y por la parte norte de Centroamérica y se encontraron pruebas serológicas en las Bahamas, Puerto Rico y Cuba. En 2004, las primeras pruebas serológicas de actividad vírica en ecosistemas sudamericanos se detectaron en septiembre y octubre en Colombia y Trinidad, donde se observaron anticuerpos neutralizantes contra el VNO en animales domésticos. CONCLUSIONES: Estos informes esporádicos de enfermedad equina, humana y aviar en América Latina y el Caribe son desconcertantes. Es necesario aislar las cepas para determinar si la atenuación del virus u otro factor explica la carga de enfermedad reducida en ecosistemas tropicales.