Placental Sampling for Understanding Viral Infections - A Simplified Protocol for the COVID-19 Pandemic / Coleta placentária para entender infecções virais - Um protocolo simplificado para a pandemia de COVID-19

Abstract Objective The coronavirus disease 2019 (COVID-19) is a pandemic viral disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The impact of the disease among the obstetric population remains unclear, and the study of the placenta can provide valuable information. Adequate sampling of the placental tissue can help characterize the pathways of viral infections. Methods A protocol of placental sampling is proposed, aiming at guaranteeing representativity of the placenta and describing the adequate conservation of samples and their integrity for future analysis. The protocol is presented in its complete and simplified versions, allowing its implementation in different complexity settings. Results Sampling with the minimum possible interval from childbirth is the key for adequate sampling and storage. This protocol has already been implemented during the Zika virus outbreak. Conclusion A protocol for adequate sampling and storage of placental tissue is fundamental for adequate evaluation of viral infections on the placenta. During the COVID-19 pandemic, implementation of this protocol may help to elucidate critical aspects of the SARS-CoV-2 infection.

Resumo Objetivo A doença do novo coronavírus (COVID-19) é uma doença viral pandêmica causada pelo coronavírus da síndrome respiratória aguda 2 (SARS-CoV-2). O impacto da doença entre a população obstétrica ainda é incerto, e o estudo da placenta pode fornecer informações valiosas. Assim, a coleta adequada do tecido placentário pode ajudar a caracterizar algumas propriedades das infecções virais. Métodos Um protocolo de coleta placentária é proposto, objetivando a garantia de representatividade da placenta, descrevendo a maneira de conservação adequada das amostras, e visando garantir sua integridade para análises futuras. O protocolo é apresentado em suas versões completa e simplificada, permitindo sua implementação em diferentes configurações de infraestrutura. Resultados A amostragem com o intervalo mínimo possível do parto é essencial para coleta e armazenamento adequados. Esse protocolo já foi implementado durante a epidemia de vírus Zika. Conclusão Um protocolo para coleta e armazenamento adequados de tecido placentário é fundamental para a avaliação adequada de infecções virais na placenta. Durante a pandemia de COVID-19, a implementação deste protocolo pode ajudar a elucidar aspectos críticos da infecção por SARS-CoV-2.

Impacto del uso de PCR múltiple en diagnóstico etiológico y tratamiento de infecciones respiratorias agudas en un hospital privado del norte del país / Impact of the use of multiplex PCR on etiological diagnosis and treatment of acute respiratory infections in a private hospital of the north of the country

Resumen Antecedentes y objetivo: Las enfermedades del sistema respiratorio son causa frecuente de prescripción de antibióticos. Actualmente se emplean nuevas tecnologías para su diagnóstico como el FilmArray Respiratory Panel. El objetivo de este estudio es identificar la correlación entre el diagnóstico y tratamiento de infecciones de vías respiratorias con el resultado de PCR para virus respiratorios. Material y métodos: Estudio descriptivo, transversal, retrospectivo, se incluyeron 134 pacientes atendidos en el Hospital Christus Muguerza en Saltillo, Coahuila. Para todos los casos se analizaron los resultados del panel y el tratamiento que recibieron los pacientes. Resultados: El 58 % recibió tratamiento antibiótico a su ingreso, el 13 % tratamiento combinado (antibiótico + antiviral), 27 % recibió tratamiento sintomático y el 2 % fue tratado con antiviral de primera instancia. Posterior al resultado el 38 % continuó con antibiótico, el 30 % con antibiótico y antiviral, 13.8 % se manejó con antiviral y el 18.2 % con tratamiento sintomático. Conclusión: A pesar de la alerta mundial por la resistencia a los antimicrobianos se sigue tratando a los pacientes con antibióticos, por una situación que se cree está influenciada por varios factores.

Abstract Background and objective: Respiratory system diseases represent one of the leading cause of prescription of antibiotics. At present, new technologies for the diagnosis are being used, including the FilmArray Respiratory Panel. The objective was to identify the correlation between the diagnosis and treatment of respiratory tract infections with the result of PCR for respiratory viruses. Material and methods: Descriptive, cross-sectional, restrospective study. 134 patients were included treated at the Christus Muguerza Hospital in Saltillo, Coahuila. For all cases, the positive results of this test and the treatment patients received were analyzed. Results: 58 % received antibiotic treatment at admission, 13 % received combined treatment (antibiotic + antiviral), 27 % received symptomatic treatment since their admission and 2 % whit antiviral. After receiving a positive result for respiratory viruses, 38 % continued with antibiotics, 30 % with antibiotics and antivirals, 13.8 % only managed with antivirals and 18.2% with symptomatic treatment. Conclusion: Although we are currently on global alert for resistance to antibiotics, there is a lack of awareness about the prescription of antibiotics, due to a situation which is believed to be influenced by several factors.

Research progress on etiologic diagnosis of ocular viral diseases / 浙江大学学报·医学版

A large number of viruses have been found to be associated with ocular diseases, including human adenovirus, human herpesvirus (HHV), human T lymphotropic virus type-1 (HTLV-1), and newly emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This group of diseases is prone to be misdiagnosed or missed diagnosis, resulting in serious tissue and visual damage. Etiological diagnosis is a powerful auxiliary mean to diagnose the ocular diseases associated with human adenovirus, herpes simplex virus 1 and varicella-zoster virus, and it provides the leading diagnosis evidence of infections with herpes simplex virus 2, Epstein-Barr virus, cytomegalovirus, HHV-6/7, HHV-8, HTLV-1 and SARS-CoV-2. Virus isolation, immunoassay and genetic diagnosis are usually used for etiologic diagnosis. For genetic diagnosis, the PCR technique is the most important approach because of its advantages of rapid detection, convenient operation, high sensitivity and high specificity.

Etiología viral de las infecciones respiratorias agudas graves en una unidad de cuidados intensivos pediátricos / Viral etiology of severe acute respiratory infections in a pediatric intensive care unit

RESUMEN Objetivos. Identificar los principales agentes etiológicos virales en pacientes con infección respiratoria aguda grave (IRAG) hospitalizados en una Unidad de Cuidados Intensivos Pediátricos (UCIP) y analizar sus características clínicas. Materiales y métodos. Estudio longitudinal prospectivo en menores de cinco años hospitalizados por IRAG en la UCIP del Instituto Nacional de Salud del Niño en Lima, Perú. Se realizaron pruebas de inmunofluorescencia directa y RT-PCR en tiempo real para el diagnóstico de virus respiratorios en muestras de aspirado traqueal o hisopado nasofaríngeo. Resultados. Se incluyeron 117 pacientes. La mediana de edad fue cuatro meses, el 66% presentaron comorbilidad y el 91% requirieron ventilación mecánica. Se identificó monoinfección por virus respiratorios en el 47% y coinfección viral en el 2,6%, siendo el virus sincicial respiratorio subtipo A (VSR-A) el más frecuente. La mediana del tiempo de hospitalización fue de 21 días y 20 (17%) pacientes fallecieron. Se encontró asociación entre el antecedente de enfermedad pulmonar crónica y la infección por el VSR-A (p=0,045) y entre el síndrome de Down y la infección por virus influenza A (p=0,01). Después de controlar por potenciales factores de confusión, se halló que la cardiopatía congénita (RR: 3,1; IC 95%: 1,3-5,8; p=0,002) y la infección nosocomial (RR: 2,6; IC 95%: 1,0-5,3; p=0,01) incrementaron el riesgo de muerte en pacientes con IRAG. Conclusiones. El VSR-A fue la etiología viral más frecuente en menores de cinco años hospitalizados por IRAG en la UCIP. No se encontró asociación entre la infección viral y la sobrevida del paciente.

ABSTRACT Objectives. To identify the main viral etiological agents in patients with severe acute respiratory infection (SARI) hospitalized in a Pediatric Intensive Care Unit (PICU) and to analyze their clinical characteristics. Materials and Methods. Prospective longitudinal study in children under five years of age hospitalized due to SARI at the PICU of t Instituto Nacional de Salud del Niño (National Children´s Hospital) in Lima, Peru. Real-time direct immunofluorescence and RT-PCR tests were performed for the diagnosis of respiratory viruses on tracheal aspirate or nasopharyngeal swab samples. Results. We included 117 patients. Median age was four months, 66% had comorbidity and 91% required mechanical ventilation. Respiratory virus monoinfection was identified in 47% and viral co-infection in 2.6%, with the respiratory syncytial virus subtype A (RSV-A) being the most frequent. The median length of hospitalization was 21 days and 20 (17%) patients died. An association was found between a history of chronic lung disease and RSV-A infection (p=0.045), and between Down syndrome and influenza A virus infection (p=0.01). After controlling for potential confounders, congenital heart disease (RR 3.1; 95% CI: 1.3-5.8, p=0.002) and nosocomial infection (RR 2.6; 95% CI: 1.0-5.3, p=0.01) were found to increase the risk of death in patients with SARI. Conclusions. RSV-A was the most common viral etiology in children under five hospitalized by SARI at the PICU. No association was found between viral infection and patient survival.

Knowledge about bacterial and viral pathogens present in wild mammals in Chile: a systematic review

This study organizes all available information about viral and bacterial pathogens of wild mammals in Chile. This was done in order to identify pathogens that have been well-documented and recognize those that have not been properly studied, determine the number of articles that have been published annually about this topic and identify regions in Chile that concentrate the highest and lowest number of studies concerning viral and bacterial pathogens. A total of 67 scientific articles published in peer-reviewed journals from 1951 to 2018 were selected for revision. Results indicate that the number of publications has increased per decade but there are years in which no articles were published. Most studies addressed Leptospira, rabies, hantavirus, Mycobacterium avium paratuberculosis (MAP) and distemper. Rodentia, Carnivora, Chiroptera and Cetartiodactyla were the most studied mammal orders. Information about presence/absence of pathogens was found for 44 wild mammal species. Research was mainly carried out in central and southern Chile and the most commonly employed methods for pathogen diagnosis were serology and molecular techniques. Overall, research in wild mammals has been directed towards the evaluation of zoonotic diseases, while vector-borne and non-zoonotic diseases have been mostly neglected by the scientific community over the years.

Conocimiento acerca de los patógenos virales y bacterianos presentes en mamíferos silvestres en Chile: una revisión sistemática / Knowledge about viral and bacterial pathogens present in wild mammals in Chile: a systematic review

Resumen Este estudio organiza toda la información disponible acerca de los patógenos virales y bacterianos de mamíferos silvestres en Chile. Esto fue realizado con el objetivo de identificar patógenos que han sido bien documentados y reconocer aquellos que no han sido apropiadamente estudiados, determinar el número de artículos que han sido publicados anualmente acerca de este tópico e identificar las regiones en Chile que han concentrado el mayor y menor número de estudios relacionados con patógenos virales y bacterianos. Para lograr esto, se seleccionó para revisión un total de 67 artículos científicos publicados en revistas evaluadas por pares desde 1951 al 2018. Los resultados indican que el número de publicaciones ha incrementado por década y hay años en los cuales no se publicaron artículos. La mayoría de los estudios se relacionan con Leptospira, rabia, hantavirus, Mycobacterium avium paratuberculosis (MAP) y distémper. Rodentia, Carnivora, Chiroptera y Cetartiodactyla fueron los órdenes de mamíferos más estudiados. Información acerca de la presencia/ausencia de patógenos fue encontrada en 44 especies de mamíferos silvestres. La mayor parte de las investigaciones buscaron patógenos en Chile sur y central y los métodos de diagnóstico más empleados para el diagnóstico de patógenos fueron serología y técnicas moleculares. En general, la investigación en mamíferos silvestres ha sido dirigida a la evaluación de enfermedades zoonóticas, mientras que aquellas enfermedades transmitidas por vectores y enfermedades no zoonóticas han sido mayormente ignoradas por la comunidad científica.

This study organizes all available information about viral and bacterial pathogens of wild mammals in Chile. This was done in order to identify pathogens that have been well-documented and recognize those that have not been properly studied, determine the number of articles that have been published annually about this topic and identify regions in Chile that concentrate the highest and lowest number of studies concerning viral and bacterial pathogens. A total of 67 scientific articles published in peer-reviewed journals from 1951 to 2018 were selected for revision. Results indicate that the number of publications has increased per decade but there are years in which no articles were published. Most studies addressed Leptospira, rabies, hantavirus, Mycobacterium avium paratuberculosis (MAP) and distemper. Rodentia, Carnivora, Chiroptera and Cetartiodactyla were the most studied mammal orders. Information about presence/absence of pathogens was found for 44 wild mammal species. Research was mainly carried out in central and southern Chile and the most commonly employed methods for pathogen diagnosis were serology and molecular techniques. Overall, research in Chilean wild mammals has been directed towards the evaluation of zoonotic diseases, while vector-borne and non-zoonotic diseases have been mostly neglected by the scientific community.

Survey of pathogens in threatened wild red-tailed Amazon parrot (Amazona brasiliensis) nestlings in Rasa Island, Brazil

ABSTRACT The red-tailed Amazon parrot (Amazona brasiliensis) is a threatened species of psittacine bird that inhabit coastal regions of Brazil. In view of the threat of this species, the aim of this study was to perform a health evaluation in wild nestlings in Rasa Island, determining the prevalence of enterobacteria and infectious agents according to type of nest. Blood samples were collected from 64 birds and evaluated for antibodies of Chlamydia psittaci by commercial dot-blot ELISA. Cloacal and oropharyngeal swabs samples were collected from 23 birds from artificial wooden nests, 15 birds from PVC nests and 2 birds from natural nests for microbiological analysis. Swab samples were collected from 58 parrots for C. psittaci detection by PCR and from 50 nestlings for Avian Influenza, Newcastle Disease and West Nile viruses' detection analysis by real-time RT-PCR. Ten bacterial genera and 17 species were identified, and the most prevalent were Escherichia coli and Klebsiella oxytoca. There was no influence of the type of nest in the nestlings' microbiota. All samples tested by ELISA and PCR were negative. There is currently insufficient information available about the health of A. brasiliensis and data of this study provide a reference point for future evaluations and aid in conservation plans.

Mosquito-transmitted viruses - the great Brazilian challenge

ABSTRACT Arboviruses pose a serious threat to public health worldwide, overloading the healthcare system and causing economic losses. These viruses form a very diverse group, and in Brazil, arboviruses belonging to the families Flaviviridae and Togaviridae are predominant. Unfortunately, the number of arboviruses increases in proportion with factors such as deforestation, poor sanitation, climate changes, and introduction of new viruses like Chikungunya virus and Zika virus. In Brazil, dengue is endemic, along with the presence of other arboviruses. The situation is complicated by the scarcity of diagnostic infrastructure and the absence of approved vaccines for these diseases. Disease control, thus, relies solely on vector control. Therefore, enhanced clinical knowledge and improved general awareness about these arboviruses are indispensable to tackle diagnostic inadequacies.

Co-infección viral respiratoria en niños hospitalizados por infección respiratoria aguda y su impacto en la gravedad clínica / Viral respiratory co-infections in pediatric patients admitted for acute respiratory infection and their impact on clinical severity

Introduction: Respiratory viruses are the leading cause of acute respiratory tract infection (ARI) in children. It has been reported that viral respiratory co-infection could be associated with severe clinical course. Objectives: To describe the frequency of viral co-infection in children admitted for AlRI and evaluate whether this co-infection was associated with more severe clinical course. Patients and Methods: Prospective, descriptive study in pediatric patients who were hospitalized for ARI, with molecular detection of at least 1 respiratory virus in nasopharyngeal sample studied by PCR-Microarray for 17 respiratory viruses. Results: 110 out of 147 patients with detection of > 1 respiratory virus were included. Viral co-infection was detected in 41/110 (37%). 22/110 children (20%) were classified as moderate to severe clinical course and 88/110 (80%) were classified as mild clinical course. In the group of moderate to severe clinical course, viral respiratory co-infection was detected in 6/22 (27.3%), compared to 35/88 (39.8 %) in the mild clinical course group. No statistically significant difference was found regarding the presence of co-infection between groups (p = 0.33). Conclusions: We detected high rates of viral co-infection in children with ARI. It was not possible to demonstrate that viral co-infections were related with severe clinical course in hospitalized children.

Introducción: Los virus respiratorios son la principal causa de infección aguda del tracto respiratorio (IRA) en pediatría. Se ha descrito que la co-infección viral podría relacionarse con infecciones virales respiratorias de curso más grave. Objetivo: Describir la frecuencia de co-infección viral en niños hospitalizados por IRA y determinar si esta co-infección se relacionó con una evolución clínica más grave. Pacientes y Métodos: Estudio descriptivo, prospectivo, en pacientes pediátricos hospitalizados por IRA entre junio y agosto 2010, que tuvieron detección molecular de al menos un virus respiratorio en muestra nasofaríngea estudiada por RPC-microarreglo para 17 virus respiratorios. Resultados: Se incluyeron 110 de 147 pacientes con detección de > 1 virus respiratorio. Se detectó co-infección viral en 41/110 (37%). En cuanto a evolución clínica, 22/110 niños (20%) se clasificaron como evolución moderada a grave (MG) y 88/110 (80%) se clasificaron como evolución leve (L). En el grupo MG se detectó co-infección viral respiratoria en 6/22 (27,3%), mientras que en el grupo L se detectó co-infección en 35/88 (39,8%). No se encontró diferencia significativa en relación a la presencia de co-infección entre ambos grupos (p = 0,33). Conclusión: Se demostró la presencia de co-infección viral en un alto porcentaje de niños con IRA. No fue posible demostrar que la presencia de coinfección viral tenga relación con una evolución clínica más grave en estos niños hospitalizados.

Infecciones virales intestinales en pediatría / Intestinal viral infections in pediatrics

Los virus que causan diarrea en humanos generalmente muestran gran trofismo por las células epiteliales del intestino delgado. El mecanismo tradicionalmente aceptado es que estos agentes causan enfermedad destruyendo gran cantidad de entericitos maduros, (sea por lisis directa o induciendo la apoptosis) los que son reemplazados por células inmaduras provenientes de las criptas. Esto lleva a una absorción inadecuada de agua, electrolitos y nutrientes, con capacidad conservada de secretar cloro y agua. A diferencia de lo que ocurre frente a patógenos bacterianos invasores, la respuesta inflamatoria del huésped es leve y no contribuye significativamente en el mecanismo de la diarrea viral. Estudios posteriores han llevado a postular mecanismos adicionales, que no serían autoexcluyentes. Se ha descrito que algunas proteínas virales no estructurales actuarían como enterotoxina. Además, jugaría un rol la alteración de las uniones estrechas con aumento del flujo paracelular de agua y electrolitos, el aumento de la secreción intestinal mediada por neurotransmisores, y la microisquemia vellositaria. El impacto de la enteritis viral es mayor y la recuperación más lenta en niños previamente desnutridos. Se ha demostrado en animales de experimentación desnutridos un notorio retraso en la recuperación de la capacidad enzimática y absortiva de la mucosa intestinal frente a una enteritis viral, lo que refuerza la necesidad de una temprana y efectiva rehabilitación nutricional durante los episodios agudos de diarrea. Es ampliamente conocido que la lactancia materna, disminuye la incidencia y severidad de las diarreas virales en niños, los primeros meses de vida.

Viruses that cause diarrhea in humans generally show great tropism due to epithelial cells of the small intestine. The traditionally accepted mechanism is that these agents cause illness by destroying large number of mature enterocytes (via direct lysis or by inducing apoptosis), which are replaced by immature cells coming from the crypts. This leads to an inadequate absorption of water, electrolytes and nutritients with conserved chloride and water secretion. In contrast to invasive bacterial pathogens, the host infl amatory response is mild and it does not contribute significantly to the mechanism of viral diarrhea. Subsequent studies have leaded to postulate additional mechanisms that would not exclude each other. It has been described that some non-structural viral proteins may act as enterotoxin. In addition, the alteration of the tight junctions with an enhanced paracellular flow of water and electrolytes, the increase of neurotransmitter mediated intestinal secretion, and the micro-ischemia of villi would also play a role. The impact of viral enteritis is larger and the recovery slower in previously undernourished children. Studies carried out on undernourished experimentation animals have demonstrated a notorious delay in the recovery of the enzymaticand absorptive capacity of intestinal mucosa after viral enteritis, which reinforces the need for early and effective nutritional rehabilitation during episodes of acute diarrhea. It is well-known that the breastfeeding reduces the incidence and severity of viral diarrheas in children during the first months of life.

Frequency of viruses associated with acute respiratory infections in children younger than five years of age at a locality of Mexico City

A locality in the district of Tlalpan, Mexico City, was selected in order to identify the viral agents in children younger than 5 years of age with acute respiratory infection (ARI). A total of 300 children were randomly selected and were included in this study for a period of 13 months. During this period nasopharyngeal exudates were collected for the isolation of viral agents. Monoclonal fluorescent antibodies were used for viral identification after cell culture. Viral infection was detected in 65 percent of the specimens. The respiratory syncytial virus (RSV) was the most common virus agent detected. Children required an average of two consultations during the study period. Two high incidence peaks were observed, one during the summer and the other during winter; the most frequent viruses during these seasons were influenza A and RSV, respectively. The largest number of viruses was isolated in the group of children between 1 and 2 years of age and in the group between 4 and 5 years of age. This study demonstrated the presence of ARI and of different viruses in a period of 13 months, as well as the most frequent viruses in children younger than 5 years of age from a community of Mexico City.

Incidence of respiratory viruses in preterm infants submitted to mechanical ventilation

Os objetivos do estudo foram determinar a incidência de infecção por vírus respiratórios em crianças pré-termo externas submetidas à ventilação mecânica e avaliar os padrões clínico, laboratorial e radiológico das infecções virais entre crianças pré-termo internadas em unidade de cuidados intensivos neonatal (NICU) com insuficiência respiratória aguda de qualquer tipo. Setenta e oito crianças pré-termo externas foram estudadas de Novembro de 2000 a Setembro de 2002. Os recém-nascidos foram classificados em dois grupos: com infecção viral (Grupo I) e sem infecção viral (Grupo II). Vírus respiratórios foram diagnosticados em 23 crianças pré-termo (29,5%); o vírus mais importante foi o sincicial respiratório (VSR) (14,1%), seguido pelo vírus influenza A (10,2%). Rinorréia, sibilância, vômitos e diarréia, pneumonia, atelectasia e infiltrado intersticial foram significativamente mais freqüentes nos recém-nascidos com infecção viral hospitalar. Houve correlação entre infecção viral hospitalar e valores baixos de proteína C-reativa. Dois pacientes com infecção mista do Grupo I faleceram durante a internação. Em conclusão, o VSR foi vírus mais incidente nestes pacientes com infecção nosocomial do trato respiratório inferior. Foi observado que, embora a maioria das infecções respiratórias virais tenham tido uma evolução favorável, alguns pacientes apresentaram quadro clínico grave e prolongado, principalmente quando houve infecção bacteriana ou fúngica concomitante.

Inoculación del virus de la enfermedad del ojo azul en verracos de la raza Pelón Mexicano / Blue Eye disease virus inoculation in mexican hairles boars

Se inocularon cinco cerdos adultos de la raza Pelón Mexicano con el rubulavirus porcino que causa la enfermedad del ojo azul, sacrificándolos a los 5, 10, 20, 30 y 45 días posinoculación para observar la secuencia semiótica y el tipo y el tipo de las lesiones en cada una de ellos. Al momento de la necropsia se obtuvieron muestras de tonsilas, pulmón, hígado, bazo, riñón, nódulo linfático mediastínico, cerebro, testículo, epidídimo, próstata vesícula seminal y glándula bulbouretral, con el fin de aislar al virus y determinar el momento en que detectaba su presencia (en cultivo celular PK 15). La manifestación durante signos sólo ocurrió en los primeros quince días posinoculación. La opacidad de la córnea se presentó al séptimo día. La edematización del testículo izquierdo se observó entre el quinto y el décimo días. La cabeza de los epidídimos mostraron nódulos granulomatosis a los 20, 30 y 45 días posinoculación. Se pudo recuperar el virus de diferentes tejidos durante todo el periodo experimental

Encefalitis equina venezolana aspectos epidemiológicos de la enfermedad entre 1962 y 1971, la Guajira venezolana / Venezuelan equine encephalitis: epidemiological aspects of the disease in the venezuelan Guajira, 1962-1971

El virus de la encefalitis equina venezolana ha venido causando brotes periódicos de la enfermedad en el área de la Guajira venezolana desde 1930. El presente trabajo resume las investigaciones epidemiológicas realizadas desde 1962 en esta zona del país, en un intento de localizar el foco enzoótico de la enfermedad. Si bien la Península de la Guajira es una región desértica, de vegetación xerófila, posee muchas lagunas de aguas salobres cubiertas de "pistia", planta acuática bajo cuyas hojas se ha demostrado la multiplicación del Culex (melanoconion), probable vector enzoótico. A este respecto, en las capturas de mosquitos practicadas en el área en estudio, hemos logrado identificar al Culex (melanoconion) aikenii, del que se ha aislado el virus en Panamá. Aunque los esfuerzos para aislar el agente durante los períodos interepidémicos han sido infructuosos hasta la fecha, se ha podido detectar la presencia de anticuerpos en cuatro especies de animales salvajes: Proechymis, Tupinambis, Didelphis y Ameiva, el primero de los cuales ha sido demostrado previamente como reservorio del virus. Parece, por tanto, que estan dadas las condiciones para el establecimineto del foco enzoótico del virus en la región, y que será cuestión de tiempo lograr el aislamiento del agente. Una vez conocidos los factores que intervienen en el ciclo enzoótico del virus, se podrá intentar un control más racional de la enfermedad