¿Existen condiciones que favorecen la reaparición del virus de la encefalitis equina venezolana en la Alta Guajira colombiana? / Do some conditions contribute to the reemergence of the Venezuelan equine encephalitis virus in the Colombian Alta Guajira?

Introducción. En los últimos 18 años, no se han vuelto a registrar epizootias de encefalitis equina venezolana en áreas con antecedentes históricos de epidemia (1925-1995) en la península de La Guajira. Objetivo. Establecer si en la Alta Guajira colombiana se mantienen las condiciones que favorecen la reaparición de las cepas epizoóticas del virus de la encefalitis equina venezolana. Materiales y métodos. La investigación se realizó en las localidades afectadas por la epidemia de 1995, y se evaluaron los siguientes aspectos: 1) abundancia y variación estacional de las poblaciones de los mosquitos vectores; 2) disponibilidad de mamíferos sensibles amplificadores del virus, y 3) conocimiento de los habitantes sobre la enfermedad y sus vectores. Resultados. La mayoría de las especies de mosquitos, incluidas las de los vectores, se encontraron durante la estación lluviosa. Aedes taeniorhynchus y Psorophora confinnis presentaron relación con la precipitación y la temperatura. Deinocerites atlanticus estuvo siempre presente, independientemente de las condiciones climáticas. No se encontraron anticuerpos de tipo IgG en los sueros de humanos menores de 17 años, tampoco en los de los animales caprinos y bovinos analizados. En la encuesta sobre conocimientos, se detectó que la tercera parte de los encuestados recordaba la última epidemia y tenía conocimientos básicos sobre la enfermedad. Solamente 20 % de las familias poseía équidos y el 8 % estaba informado sobre la necesidad de vacunarlos. Conclusiones. Se mantienen algunas condiciones epidemiológicas que eventualmente podrían favorecer la reaparición del virus, pero el número de equinos en riesgo es escaso, lo cual constituye el cambio más notable y lo que, aparentemente, ha impedido la reaparición del virus.

Introduction: In the last 18 years, epizootics of Venezuelan equine encephalitis have not occurred in places with historic epidemic register (1925-1995) in the Guajira Peninsula, Colombia. Objective: To assess if the Guajira Peninsula, Colombia, still maintains the epidemiological conditions for Venezuelan equine encephalitis virus reemergence. Materials and methods: Research was carried out in places affected by the 1995 epidemic. We evaluated: 1) abundance and seasonal variation of vector mosquito populations; 2) availability of mammals that are potential amplifiers of the virus, and 3) knowledge among the community about the disease and its vectors. Results: Most of the 16 mosquito species were found during the rainy season. Aedes taeniorhynchus and Psorophora confinnis showed direct relation with rainfall and temperature. In contrast, the dominant species, Deinocerites atlanticus , was always present in the collections, regardless of climatic conditions. No IgG antibodies were found in humans younger than 17 years old, goats or bovine sera. One third of those interviewed remembered the last epidemic and had basic understanding of the disease. Only 20% of the families were owners of equines, and 8% was informed of the importance of equine vaccination. Conclusions: Some epidemiological conditions that eventually could help epizootic Venezuelan equine encephalitis virus reemergence are maintained. However, an abrupt decrease in the number of susceptible equines was found in the area. Apparently, this new condition has not allowed the virus reemergence and is the biggest observed change.

Establishment of a One-Step Real-Time RT-PCR Method for the Detection of Venezuelan Equine Encephalitis Virus / 病毒学报

Venezuelan equine encephalitis (VEE) is a zoonotic disease caused by the Venezuelan equine encephalitis virus (VEEV) complex. This disease has not yet been reported in China, and it is therefore essential to establish a rapid and accurate method for detection of the virus in order to prevent and control this disease. In this study, a one-step real-time quantitative RT-PCR method was developed for the detection of the VEEV complex. A pair of specific primers and a Taqman probe were designed corresponding to a conserved region of the VEEV gene nspl, allowing the detection of all known strains of different sub- types of the virus. Using RNA synthesized by in vitro transcription as template, the sensitivity of this method was measured at 3.27 x 10(2) copies/microL. No signal was generated in response to RNA from Chikungunya virus (CHIKV), nor to RNA encoding the nsp1 fragment of Eastern equine encephalitis virus (EE-EV) or Western equine encephalitis virus (WEEV), all of which belong to the same genus as VEEV. This indicates that the method has excellent specificity. These results show that this one-step real-time quantitative RT-PCR method may provide an effective tool for the detection of VEEV in China.

First detection of Rio Negro virus (Venezuelan equine encephalitis complex subtype VI) in Córdoba, Argentina

Rio Negro virus (RNV) (Venezuelan equine encephalitis subtype VI) circulates only in Argentina; in northern provinces, isolates have been obtained from mosquitoes and rodents since 1980 and have been associated with acute febrile illness in humans. However, no studies of RNV have been performed in the central area of the country. We carried out molecular and serological detection of RNV in Córdoba, a province of the central part of the country, in mosquitoes and humans, respectively. One mosquito pool tested positive for alphavirus RNA by reverse transcriptase-nested polymerase chain reaction (RT-nested PCR). Subsequent sequencing determined that this alphavirus grouped with RNV. Serological studies detected antibodies to RNV in one human serum sample, which was obtained during the same period that RNV was detected using the aforementioned molecular methods. This is the first report of RNV circulation in the central area of Argentina, indicating an expansion of its original distribution. These results highlight the importance of strengthening surveillance procedures in endemic areas, as well as in new regions where RNV may emerge.

Seroprevalence of antibodies to Venezuelan equine encephalitis complex (subtypes IAB and VI) in humans from General Belgrano Island, Formosa, Argentina

This work presents the results of the detection of antibodies (immunoglobulin G) for subtypes I and VI of VEE viruses complex (Togaviridae family) in people from the General Belgrano island, Formosa province (Argentina). The prevalence of neutralizing (NT) antibodies for subtype VI was from 30 percent to 70 percent and the prevalence of antibodies inhibitory of hemagglutination (HI) was of 0 percent in the first and second inquiry respectively. For the subtype IAB the prevalence of NT antibodies was from 13 percent to 3.6 percent, similar to the prevalence total for both subtypes. HI antibodies were not detected in any inquiries for any subtype. It was observed that both subtypes circulate simultaneously, while subtype VI remains constant with some peaks, subtype I was found in low level

Encefalitis equina venezolana: perfil clínico epidemiológico de la epidemia ocurrida en 1995 / Equine encephalitis in Venezuela: a clinical epidemiological profile of the 1995 epidemic

La encefalitis equina venezolana ha venido presentándose en brotes episódicos en la Guajira Venezolana desde aprox. 1936. En 1938 se aisló el agente causal por vez primera de un caballo enfermo en Venezuela. El síndrome predominante es el de una enfermedad autolimitada semejante a la gripe, y apenas 4 por ciento de las personas infectadas, principalmente niños menores de 15 años, sufre encefalitis. La mortlidad de niños menores de cinco años con encefalitis es de 35 por ciento. Se describe y analiza el perfil clínico epidemiológico de la epidemia de Encefalitis Equina Venezolana en cinco Municipios (Maracaibo, Mara, Insular, Padilla, Páez, Miranda) del estado Zulia (Venezuela) ocurrida entre el 15 de julio y el 17 de octubre de 1995. Se revisaron los datos obtenidos del departamento de vigilancia epidemiológica del Estado Zulia, teniendo un total de 11.072 casos con diagnóstico clínico-epidemiológico de Encefalitis Equina Venezolana, en una población de 574.769 habitantes comprendida por los cincos municipios ya citados, con tasa de ataque de 1,92 por ciento, no hay diferencia significativa en el sexo, el grupo etario más afectado son los menores de 5 años ocupando más de la mitad de la mortalidad con 8 casos, incluyéndose en este grupo dos muertes en recién nacidos cuyas madres se enfermaron en el último trimestre del embarazo

Estudo da competência vetora de populaçöes de Aedes (Stegomyia) albopictus (Skuse) (Diptera: Culicidae) do Estado de Säo Paulo para os vírus dengue e encefalomielite equina venezuelana e do efeito da exposiçäo à infecçäo na longevidade / Study of the vector competence of populations of Aedes (Stegomyia) albopictus (Skuse)(Diptera: Culicidae) from Säo Paulo State (Brazil) for dengue and Venezuelan equine encephalitis viruses and the exposition to infection on the longevity

Avaliar a competência vetora de populaçöes de Ae. albopictus do Vale do Paraíba (localidade urbana) e do Vale do Ribeira (localidade rural)(Estado de Säo Paulo) para o vírus DENV-1 e DENV-2 e os subtipos IC, ID e IF VEEV, e a influência da sobrevivência dos mosquitos. Fêmeas com 4-6 dias de idade foram infectadas por via oral com DENV-1 E DENV-2 e com os subtipos IC, ID E IF do VEEV. Foram determinadas as porcentagens de infecçäo, disseminaçäo e transmissäo dos vírus. Foram construídas tabelas de sobrevida em mosquitos näo expostos e expostos a vírus. As taxas de infecçäo para DENV-1 e DENV-2 foram baixas nas duas populaçöes de Ae. albopictus. Näo foi detectada transmissäo desses vírus, mas sim a disseminaçäo deles. A longevidade dos mosquitos näo foi afetada pela exposiçäo à infecçäo ao DENV. As taxas de infecçäo foram elevadas para os subtipos IC e ID do VEEV, mas baixas para o subtipo IF. Porém os títulos de infecçäo nos três casos foram elevados. Foi detectada a transmissäo dos subtipos IC e ID. A longevidade dos mosquitos diminuiu em decorrência da exposiçäo à infecçäo com o subtipo IC. As populaçöes de Ae. albopictus avaliadas säo susceptíveis à infecçäo pelo DENV e competentes para transmitir os subtipos enzoóticos e epizoóticos do VEEV. Outros estudos com o subtipo IF devem ser realizados. A longevidade foi afetada pela infecçäo com o subtipo IC do VEEV.

Encefalitis equina venezolana / Encefalitis

Contiene: 1. Introducción; 2. Microbiología; 3. Patogenia/fisiopatología; 4. Anatomía patológica; 5. Aspectos clínicos; 6. Diagnóstico de laboratorio; 7. Diagnóstico diferencial; 8. Aspectos epidemiológicos; 9. Procedimientos para la vigilancia epidemiológica; 10. Medidas de prevención y control; 11. Anexos; 12. Referencias bibliográficas

Investigaciones sobre las encefalitis equinas en Colombia, 1995-2000: Programa de Salud Pública Veterinaria División de Prevención y Control de Enfermedades / Encephalomyelitis equine in Colombia, 1995-2000: Veterinary Public Health Programme. Division of Control and Prevention Diseases

RESULTADOS OBTENIDOS: 1) Identificación del ciclo de transmisión de EEV en el Magdalena Medio colombiano. 2) Primeras evidencias de existencia de ciclos de transmisión aún sin caracterizar, que posiblemente involucran virus epizoóticos EEV en ciclos enzoóticos en la región del Casanare. 3) Se refuerzan los hallazgos que los virus epizoóticos IAB y IC evolucionan periódicamente a partir de progenitores EEV enzoóticos subtipo ID, los cuales circularían continua y silenciosamente en bosques húmedos de Colombia y Venezuela. 4) Ubicación preliminar de bosques con circulación activa del virus EEV enzoótica subtipo ID con ayuda de imágenes de satélite y Geographic Information System (GIS) en Colombia y Venezuela. 5) Demostración de transmisión continua de virus EEV ernzoótico en la región del Magdalena Medio por más de 30 años sin generar actividad epidémica o epizoótica "in situ". 6) Evidencia de anticuerpos para virus EEV en bovinos sin inmunización previa, en la proximidad de un bosque con ciclo enzoótico del Magdalena Medio (San Miguel). 7) Diferenciación de aislamientos de virus EEV mediante la técnica Single Strand Conformational Polymorphism (SSCP)

Arboviruses Pathogenic for man in Brazil

Os mais importantes aspectos clinicicos e ecoepidemiologicos e aspectos preventivos acerca das arboviroses associadas com doenca humana no Brasil sao discutidos.Trinta e seis arbovirus dentre os tipos presentemente isolados no Pais tem sido incriminados como causadores de doenca humana. Destes, cinco sao importantes em termos de saude publica pois estao associados com epidemias , sao os virus Dengue (DEN), Mayaro(MAY), Oropouche (ORO), Rocio (ROC) e Febre amarela (FA). DEN e ORO estao associados com doenca humana epidemica em areas urbanas enquanto MAY, ROC e FA especialmente em areas rurais. Basicamente, o virus ORO determina um quadro febril algumas vezes acmpanhado por meningite asseptica. MAY e DEN sao responsaveis por quadros exantematicos, sendo que DEN, nos ultimos anos tem sido associado com quadros de febre hemorragica, o que sabidamente e o mecanismos pelo qual o virus FA determinaa sua apresentacao clinica classica e o ROC esta associado com graves quadros de encefalite. Trinta e um outros arbovirus tem sido associados com doenca febril benigna em poucos e esporadicos casos. Afora DEN e os Arenavirus Flexal e Sabia ( nao sao arbovirus), todos os arbovirus envolvidos com doenca humana na AmazoniaBrasileira, sao mantidos em natureza atraves de um ciclo silvestre desenvolvido na floresta, onde diversas especies de insetos hematofagos e vertebrados silvestres atuam como vetores e hospedeiros, respectivamente.O virus DEN tem um ciclo urbano em que o mosquito Aedes aegypti e o vetor e o homem atua como hospedeiro. Os arenavirus sao transmitidos diretamente ao homen atraves de excretas de roedores que sao seus principais hospedeiros.Excetuando os cinco virus associados com epidemias que causam um grande impacto socio-economico, inclusive levando a morte, casos verificados com FA, DEN e ROC, o verdadeiro papel dessesvirus como agentes sistematicos de doencas humanas e ainda puco conhecido. Novos estudos sao necessarios para esclarecer aspectos ainda obscuros acerca da epidemiologia da maioria desses arbovirus

Historical, epidemiological and ecological aspects of arboviruses in Argentina: Togaviridae, Alphavirus

This is a review of the arboviruses in Argentina belonging to families Flaviridae, Bunyaviridae and Rhabdoviridae. Of the many viruses belonging to these families, the flavivirus St. Louis encephalitis (SLE), has been most intensively studied. SLE virus strains have been recovered from three sources: 2 strains from humans with an undifferentiated, febrile disease; 6 from mosquitoes; and 2 from rodents. The viruses recovered from rodents are attenuated and those from mosquitoes are virulent based on a neuroinvasiveness test in mice; the degree of virulence of the mosquito strains remain to be analyzed. Serological surveys indicate a wide distribution and endemicity of SLE virus in the temperate and subtropical areas (central and northern Argentina), but no data are available from the andean region or from the South. The virulent SLE virus strains appear to be transmitted between Culex (Cx.)spp. from which they were isolated, and wild birds, based on antobody prevalence. A urban cycle may involve Cx. quinquefasciatus (source of a viral isolate and a competent experimental vector) and abundant birds (house sparrows, doves, and/or chickens), chickens are experimentally competent host species. Despite similarities in the ecology of SLE between Argentina and North America, urban outbreaks of SLE have not been recognized. Possible explanations for this discrepancy include virus strain differences in virulenc, ecologic factors determining the rate of virus transmission, and the lack of disease recognition and specific laboratory diagnosis of human meningoencephalitis. The transmission cycle of attenuated SLE virus strains isolated from rodentshas not been studied. Ilheus virus has isolated only once from a human being. The available serological data are difficult to interpret due to cross-reactivity with other flaviviruses, and the ecologyand medical importance of this agent remain uncertain. Dengue has not been recognized in Argentina since 1916, although is vector, Aedes aegypti, was not erradicated until 1963. Dengue was previously present in coastal localities of Chaco. Corrientes and Misiones Provinces. Within the last few years, Argentina was reinfested by Ae. aegypti. Although no human cases have vet been reported, outbreaks of dengue in bordering countries (Brazil, Paraguay, Bolivia) since 1986, cleary signal that the country in once againat risk of importantion ans spread of the virus

Arthropod-Borne viral Diseases in Peru

Arthropode-Borne viral diseases have been a significant cause of morbidity and mortality for several decades in Peru. Epidemics and epizootics of Venezuelan equine encephalitis (VEE), subtype IAB virus occurred among humans and equine at intermittent intervals from 1925 through 1973 along the Pacific coastal plains, extending southward from the most northern Departament of Tumbes to the Departament of Ica. While the VEE IAB virus has not been detected since 1973, several isolates of VEE ID and an isolate VEE IIIC were obtained during 1971 and 1975 from mosquitoes and/or sentinel hamster in Quistococha, northeastern Amazon region. In 1994, the first human cases, associated with VEE virus ID were diagnosed among Peruvian soldiers near Pantoja, northern Amazon region, and during 1995, primarily among students and military personnel in Iquitos, northastern Amazon region. As early as 1913 , a disease resembling yellow fever was recognized in the Amazon region Peru. Outbreaks of this disease have continued to occur, apparently at annual interval, with the most recent and the largest sylvan outbreak ever recorded in Peru being documented during 1995 along the eastern foothills of the Andes Mountains. In 1990, dengue (DEN) 1 and DEN4 were first isolated in Peru during an outbreak of DEN fever among residents of the city of Iquitos, northeastern Amazon basin region. Seroepidemiological and case surveillance studies conducted 1992 through 1995 documented that DEN 1 continued to cause cases of DEN fever in Iquitos, and in 1995, an outbreak was associated with the introduction of DEN 2 into the community. Outbreaks of DEN fever, associated with DEN 1 occurred during 1994 and 1995 in the northern coastal cities of Tumbes and Piura, and in Pucallpa, Amazon basin region. In 1995, the first isolations of DEN 2 were obtained from febriles cases in Tumbes, Piura and Pucallpa. Although 2 serotypes of DEN were associated with human infection, none of the cases presented with hemorragic manifestations. The first isolations of Oropouche (ORO) fever virus were obtained during 1992 from febrile patients in Iquitos. The virus was isolated during 1994 from febrile cases and serological results revealed that ORO was the cause of an outbreak in the southeastern Amazon region. A single isolate of ORO virus was obtained during 1995 from a febrile patient in Iquitos

Relación entre mosquitos vectores y aves acuáticas en la transmisión potencial de dos arbovirus / The relationship between mosquito vectors and aquatic birds in the potential transmission of 2 arboviruses

The authors studied for two years the role of the chicks of aquatic birds in the arboviral cycles in coastal lagoons in central Panama in order to determine the relation between Culex (Melanoconion) ocossa and Mansonia (Mansonia) dyari mosquitoes in the transmission and dissemination of the viruses of Saint Louis Encephalitis (SLE) and Venezuelan Equine Encephalitis (VEE). Mosquitoes were captured every fifteen days on two consecutive nights to isolate the virus, using light traps (CDC) and baited traps. The attempts to isolate the virus were made using Vero cell cultures and the determination of antibodies was performed. The results of the serologic tests seem to indicate that four bird species: the ex (?) heron (Bubulcus ibis), the American heron (Casmerodius albus), the spoon-billed duck (Cochlearius cochlearius) and the needle crow (Anhinga anhinga) could function as intermediate hosts in the transmission cycle of SLE. Two species, the ibis (Endocimus albus) and the spoon-billed duck (Cochlearius cochlearius) could also be intermediate hosts of VEE in the coastal lagoons of Panama. The presence of antibodies in chicks could indicate an infection acquired recently, after their birth, in this area. The VEE virus was recovered from blood filled mosquitoes which had fed on a spoon-billed duck probably infected and exposed in a Trinidad #10 trap. No SLE virus was isolated. Other unknown viruses were isolated from mosquitoes selected for these studies, such as C. ocossa and M. dyari. The results obtained with these studies indicate the need for more studies utilizing new field techniques in order to establish a link between SLE and VEE, the vector mosquitoes and the aquatic birds in the coastal lagoons of the area under investigation

Encefálitis equina venezolana: determinación de anticuerpos en la población humana del Municipio Miranda, Estado Zulia, Venezuela / Venezuelan equine encephalytis: antibodies determination in the human population of Miranda country, Zulia state, Venezuela.

Con el objeto de determinar la prevalencia de anticuerpos para el virus de la Encefálitis Equina Venezolana en las poblaciones de Los Puertos de Altagracia y Sabaneta de Palmas, del Municipio Miranda, del Estado Zulia, en Venezuela, se estudiaron 199 individuos, 57 provenientes de Los Puertos de Altagracia y 142 de Sabaneta de Palmas. Estos se clasificaron en mayores y menores de 15 años (57,2 por ciento ). Las muestras de sangre fueron procesadas para la prueba de Inhibición de la Hemaglutinación, usando antígeno preparado a partir de la cepa Guajira de EEV y a un pH de 6,5. Se encontró que las muestras provenientes de Los puertos de Altagracia resultaron negativas, mientras que de las 142 muestras de Sabaneta de Palmas, 17 fueron positivas (11,97 por ciento ). De éstas, sólo 1 provenía de un menor de 15 años (5,85 por ciento ) y 16 de mayores de 15 años (94,15 por ciento ). Los títulos de los positivos fueron superiores a 1:160 en el 80 por ciento de los casos. Habiendo sido Sabaneta de Palmas una de las poblaciones más afectadas por la epidemia ocurrida en 1962 en el Municipio Miranda, y permaneciendo alta la positividad de los afectados con títulos bastante elevados, podría concluirse que esta pobación puede representar una zona enzoótica similar al Municipio Páez, donde se ha descrito una situación similar de alta positividad y elevados títulos, muchos años despues de la última epidemia