Yellow fever virus maintenance in Trinidad and its dispersal throughout the Americas.

Trinidad, like many other American regions, experiences repeated epizootics of yellow fever virus (YFV). However, it is unclear whether these result from in situ evolution (enzootic maintenance) or regular reintroduction of YFV from the South American mainland. To discriminate between these hypotheses, we carried out a Bayesian phylogeographic analysis of over 100 prM/E gene sequences sampled from 8 South American countries. These included newly sequenced isolates from the recent 2008-2009 Trinidad epizootic and isolates derived from mainland countries within the last decade. The results indicate that the most recent common ancestor of the 2008-2009 epizootic existed in Trinidad 4.2 years prior to 2009 (95% highest probability density [HPD], 0.5 to 9.0 years). Our data also suggest a Trinidad origin for the progenitor of the 1995 Trinidad epizootic and support in situ evolution of YFV between the 1979 and 1988-1989 Trinidad epizootics. Using the same phylogeographic approach, we also inferred the historical spread of YFV in the Americas. The results suggest a Brazilian origin for YFV in the Americas and an overall dispersal rate of 182 km/year (95% HPD, 52 to 462 km/year), with Brazil as the major source population for surrounding countries. There is also strong statistical support for epidemiological links between four Brazilian regions and other countries. In contrast, while there were well-supported epidemiological links within Peru, the only statistically supported external link was a relatively weak link with neighboring Bolivia. Lastly, we performed a complete analysis of the genome of a newly sequenced Trinidad 2009 isolate, the first complete genome for a genotype I YFV isolate.

Yellow fever virus maintenance in Trinidad and its dispersal throughout the Americas

Trinidad, like many other American regions, experiences repeated epizootics of yellow fever virus (YFV). However, it is unclear whether these result from in situ evolution (enzootic maintenance) or regular reintroduction of YFV from the South American mainland. To discriminate between these hypotheses, we carried out a Bayesian phylogeographic analysis of over 100 prM/E gene sequences sampled from 8 South American countries. These included newly sequenced isolates from the recent 2008-2009 Trinidad epizootic and isolates derived from mainland countries within the last decade. The results indicate that the most recent common ancestor of the 2008-2009 epizootic existed in Trinidad 4.2 years prior to 2009 (95% highest probability density [HPD], 0.5 to 9.0 years). Our data also suggest a Trinidad origin for the progenitor of the 1995 Trinidad epizootic and support in situ evolution of YFV between the 1979 and 1988-1989 Trinidad epizootics. Using the same phylogeographic approach, we also inferred the historical spread of YFV in the Americas. The results suggest a Brazilian origin for YFV in the Americas and an overall dispersal rate of 182 km/year (95% HPD, 52 to 462 km/year), with Brazil as the major source population for surrounding countries. There is also strong statistical support for epidemiological links between four Brazilian regions and other countries. In contrast, while there were well-supported epidemiological links within Peru, the only statistically supported external link was a relatively weak link with neighboring Bolivia. Lastly, we performed a complete analysis of the genome of a newly sequenced Trinidad 2009 isolate, the first complete genome for a genotype I YFV isolate.

Experimental infection of the Sigmodon alstoni cotton rat with Caño Delgadito virus, a South American hantavirus.

Forty-eight Sigmodon alstoni (Alston's cotton rat) were inoculated with Caño Delgadito (CDG) virus to extend our knowledge and understanding of the natural host relationships of the hantaviruses indigenous to the Americas. Infectious CDG virus was recovered from oropharyngeal secretions, urine, or solid tissues of nine of 12 animals killed on day 9 post-inoculation (PI), 14 of 24 animals killed on day 18 or 27 PI, and none of 12 animals killed on day 54 PI. In addition, virus-specific RNA was detected in the kidneys of six of the 12 animals killed on day 54 PI, and adult cotton rats inoculated with the kidneys of four animals killed on day 54 PI developed antibody to CDG virus. Collectively, the results indicate that CDG virus can establish lengthy (perhaps lifelong) infections in Alston's cotton rat and thus support the concept that S. alstoni is the principal host of CDG virus.

Serotipos y genotipos de virus dengue circulantes en Venezuela, 1990 - 1997 / Serotypes and genotypes of dengue virus circulating in Venezuela, 1990 - 1997

Debido a la severidad de las epidemias de dengue hemorrágico registradas en los últimos años en Venezuela, se realizó el análisis retrospectivo de los serotipos de virus dengue circulante en el país y la evolución epidemiológica molecular del serotipo dengue 2. Los resultados presentados indican que los virus dengue tipos 1, 2 y 4 son endémicos en Venezuela y circulan simultáneamente durante todo el año en las grandes ciudades, sin embargo se ha observado que durante los períodos epidémicos un serotipo determinado es predominante y desplaza casi totalmente el serotipo circulante en el período epidémico anterior. Se propone que la emergencia de la fiebre hemorrágica por dengue en Venezuela en 1989 está asociada a la introducción de virus dengue 2 genotipo Asiático, el cual es reconocido por ser más virulento y reemplazó el genotipo Caribe autóctono en las Américas.

Virus e hiperactividad bronquial / Viruses and bronchial hyperactivity

A 52 niños de ambos sexos entre los 6 meses y 12 años de edad que acudieron con crisis de tos, disnea y sibilancias al Servicio de Emergencia del Departamento Pediátrico "Luisa Cáceres de Arismendi" del Hospital General "José Ignacio Baldo", se les recolectó muestras de secreciones nasofaríngeas para aislamiento y cultivo de agentes virales. en 19 de ellos (36,53%), se aislaron dichos agentes. el Virus Sincicial Respiratorio, fue el gérmen más observado en las edades de 0 a 2 años (31,6% de los infectados), mientras que el Rinovius lo fue en los grupos de edades de 3 a 12 años (11% de los infectados). Se hacen comentarios y conclusiones