Febre do Nilo Ocidental / West Nile fever

A Febre do Nilo Ocidental (FNO) é uma infecção viral transmitida por meio da picada de mosquitos, principalmente do gênero Culex (pernilongo) infectados pelo agente etiológico, cujos hospedeiros naturais são algumas espécies de aves silvestres, que atuam como amplificadoras do vírus e como fonte de infecção para os vetores. Tal doença pode também infectar humanos, equinos, primatas e outros mamíferos sendo que, homem e equídeos são considerados hospedeiros acidentais e terminais, uma vez que a contaminação pelo vírus se dá por um curto período de tempo e em níveis insuficientes para infectar mosquitos, encerrando o ciclo de transmissão (WHO, 2017; ECDC , 2022a; CDC, 2017; BRASIL, 2021)

West Nile Fever (WNF) is a viral infection transmitted through the bite of mosquitoes, mainly of the Culex genus (legged mosquito) infected by the etiological agent, whose natural hosts are some species of wild birds, which act as amplifiers of the virus and as source of infection for the vectors. Such a disease can also infect humans, horses, primates and other mammals, and humans and horses are considered accidental and terminal hosts, since contamination by the virus occurs for a short period of time and at levels insufficient to infect mosquitoes, ending the transmission cycle (WHO, 2017; ECDC, 2022a; CDC, 2017). ; BRAZIL, 2021)

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.

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...

Mosquitos (Díptera: Culicidae) vectores potenciales de arbovirus en la región de Urabá, noroccidente de Colombia[

Introducción. Los estudios encaminados a conocer los parámetros ecológicos de las poblaciones de mosquitos selváticos, permiten establecer el riesgo de transmisión de arbovirus y aportar recomendaciones sobre prevención, vigilancia y control a las autoridades de salud. Objetivo. Determinar la diversidad y abundancia de mosquitos nocturnos y crepusculares, potenciales vectores de arbovirus en zonas rurales de Apartadó y Turbo, Antioquia. Materiales y métodos. Se realizaron muestreos trimestrales. Para la recolección de mosquitos se usaron trampas CDC, Shannon y cebo humano protegido, en fragmentos de bosque, entre las 18:00 y las 06:00 horas. Se estimaron los índices de diversidad y abundancia de especies. Resultados. Se capturaron 583 mosquitos de 10 génerosy 27 especies. Las especies más abundantes fueron Coquilletidia venezuelensis (14,6 %), Aedes scapularis (14,08 %), Psorophora ferox (10,82 %) y Culex quinquefasciatus (10,3 %). La riqueza específica y los índices ecológicos calculados fueron mayores en Turbo; el fragmento de bosque estudiado en Turbo se considera de mayor riqueza y uniformidad de especies. El hallazgo de Cx. pedroi, Ae. scapularis, Ae. angustivittatus, Cq. venezuelensis, Cx. nigripalpus, Cx. quinquefasciatus, Cx. declarator, Mansonia titillans, Ma. pseudotitillans, Ps. ferox y Trichiprosopon digitatum reportados como vectores de arbovirus, alerta sobre la posibilidad de transmisión en la zona. Conclusión. La diversidad y abundancia de mosquitos en la zona de estudio son altas. Los análisis ecológicos más los reportes previos de capacidad vectorial de algunas de las especies registradas, permiten concluir que en la zona se pueden presentar brotes de arbovirosis.

Mosquitoes (Diptera: Culiciadae) as potential vectors of arbovirused in the Urabá region, Northwest of Colombia.

Introduction. Studies directed to investigate ecological parameters of sylvatic mosquitoes populations permit the establishment of risk levels in the transmission of arboviruses and provide the basis for recommendations to health authorities about prevention, surveillance and control. Objective. To establish the diversity and abundance of mosquitoes vectors of arbovirus in rural areas of Apartadó and Turbo, Antioquia. Materials and methods. Quarterly sampling was done. For mosquito collections in forest fragments, CDC traps, Shannon traps and human landing methods were used. Diversity and abundance indices were calculated. Results. Five hundred eighty-three mosquitoes were collected and identified in 10 genera and 27 species. The most abundant species were as follows: Coquilletidia venezuelensis (14.6%), Aedes scapularis (14.1%), Psorophora ferox (10.8%) and Culex quinquefasciatus (10.3%). Species richness and ecological indexes were highest in Turbo municipality; where the forest fragment was considered highest in species richness and uniformity. The identification in the samples of Culex pedroi,Ae. scapularis, Aedes angustivittatus, Cq. venezuelensis, Culex nigripalpus, Cx. quinquefasciatus, Culex declarator, Mansonia titillans, Mansonia pseudotitillans, Ps. ferox andTrichoprosopon. Digitatum--allpreviously reported as arbovirus vectors--warns about the possibility of arbovirus transmission in the zone. Conclusions. Mosquito diversity and abundance in the study area was very high. The ecological analysis, plus previous reports about vector competence of several of the recorded species, permits the conclusion that arbovirus outbreaks can occur in the Urabá region.

Presença de culicídeos em município de porte médio do Estado de São Paulo e risco de ocorrência de febre do Nilo Ocidental e outras arboviroses / The presence of Culicidae species in medium-sized cities in the State of São Paulo, Brazil and the risk of West Nile fever and other arbovirus infection

INTRODUÇÃO: O objetivo deste estudo foi mensurar a diversidade de espécies de culicídeos, descrever sua abundância e variação sazonal em áreas urbanas e matas de São José do Rio Preto, SP, e discutir o risco de ocorrência de arboviroses. MÉTODOS: Coletas de larvas e de mosquitos adultos foram realizadas mensalmente, em 2006 e 2007, em área urbana e em quatro fragmentos de mata. No perímetro urbano, coletaram-se larvas nos sítios mais prováveis de oviposição para mosquitos do gênero Culex e nas matas foi realizada a coleta de mosquitos adultos, sendo que em duas utilizaram-se armadilhas CDC à noite e, em duas, aspirador de Nasci de dia. RESULTADOS: Na área urbana identificaram-se 34 espécies de culicídeos em um total de 8.683 exemplares; destes, 80,7% corresponderam ao Culex quinquefasciatus, 9,6% ao Culex grupo Coronator, 3,2% ao Aedes albopictus (3,2%) e 1,1% ao Ochlerotatus fluviatilis. A abundância de larvas de Cx. quinquefasciatus correlacionou-se negativamente com a chuva. Nas quatro matas, foram coletados 2.268 mosquitos distribuídos entre 10 gêneros, 46 espécies ou grupos. As mais abundantes foram Aedeomyia squamipennis, Culex. coronator, Culex (Mel.) seção Melanoconion, Culex declarator, Ochlerotatus scapularis, Anopheles triannulatus, Culex bidens/interfor e Culex habilitator/pseudojhantinosoma. CONCLUSÕES: A abundância de Cx. quinquefasciatus na área urbana e a presença de outros culicídeos nas áreas urbanas e de matas apontam para a possibilidade de transmissão do vírus do Nilo Ocidental e de outras arboviroses em São José do Rio Preto e outras cidades do Brasil, sendo fundamental o estabelecimento de medidas visando à vigilância destas arboviroses.

INTRODUCTION: The objectives for this study were to measure the diversity of Culicidae species, describe their abundance and seasonal variation in São José do Rio Preto, SP, and discuss the risk of arbovirus infections. METHODS: The collection of larval and adult mosquitoes was conducted monthly from 2006 to 2007 in an urban area and four sections of forested land. In the urban area, larvae were collected from sites where oviposition by Culex mosquitoes was most likely to occur. At two of the four sites in the forested land, adult mosquitoes were collected with the use of CDC traps at night, and a Nasci aspirator was used in the daytime at the two other collection sites. RESULTS: In the urban area, 34 Culicidae species were identified out of a total sample of 8,683 specimens; of these specimens, 80.7% were Culex quinquefasciatus, 9.6% were Culex coronator, 3.2% were Aedes albopictus, and 1.1% were Ochlerotatus fluviatilis. The abundance of Cx. quinquefasciatus larvae was negatively related to rainfal. In the woods, 2,268 mosquitoes were collected, representing 10 genera and 46 species. The most abundant mosquito species were Aedeomyia squamipennis, Culex coronator, Culex (Mel.) Melanoconion section, Culex declarator, Ochlerotatus scapularis, Anopheles triannulatus, Culex bidens/interfor and Culex habilitator/pseudojhantinosoma. CONCLUSIONS: The abundance of Cx. quinquefasciatus in the urban area and the presence of other Culicidae species in urban areas and forested land point to the possibility of the transmission of West Nile virus and other arbovirus infections in São José do Rio Preto and other cities. Thus, the enacting of measures aimed at the surveillance of these arbovirus infections is essential.

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.

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.

Experimental studies on the vector potential of certain Culex species to West Nile virus.

Experimental studies were carried out to determine the vector potential of four species of mosquitoes to West Nile (WN) virus, viz. Culex tritaeniorhynchus, Cx. vishnui, Cx. bitaeniorhynchus and Cx. univittatus. All the four species of mosquitoes successfully transmitted and supported the growth of WN virus. The study indicated that the four species of mosquitoes could act as potential vectors of WN virus in nature.

Comparison of vector competence for West Nile virus of colonized populations of Culex tritaeniorhynchus from southern Asia and the Far East.

Seven colonized stocks of Cx. tritaeniorhynchus from different geographic areas of Southern Asia and the Far East were assayed for susceptibility to WN virus infection by membrane feeding and by intrathoracic inoculation. Infected females also were tested for their ability to transmit virus to baby mice. No geographic pattern of differential susceptibility to WN virus infection was apparent from the experiments; however, the per os ID50 of one strain from Khulna, Bangladesh was over 10-fold greater than the ID50's of stocks from Karachi, Pakistan and Sendai, Japan. No difference in susceptibility was found by parenteral inoculation of virus. Likewise, greater than or equal to 90% of infected females from all the colonies were able to transmit virus.