Transmission of Guanarito and Pirital viruses among wild rodents, Venezuela.

Samples from rodents captured on a farm in Venezuela in February 1997 were tested for arenavirus, antibody against Guanarito virus (GTOV), and antibody against Pirital virus (PIRV). Thirty-one (48.4%) of 64 short-tailed cane mice (Zygodontomys brevicauda) were infected with GTOV, 1 Alston's cotton rat (Sigmodon alstoni) was infected with GTOV, and 36 (64.3%) of 56 other Alston's cotton rats were infected with PIRV. The results of analyses of field and laboratory data suggested that horizontal transmission is the dominant mode of GTOV transmission in Z. brevicauda mice and that vertical transmission is an important mode of PIRV transmission in S. alstoni rats. The results also suggested that bodily secretions and excretions from most GTOV-infected short-tailed cane mice and most PIRV-infected Alston's cotton rats may transmit the viruses to humans.

Natural host relationships of hantaviruses native to western Venezuela.

Strains of Caño Delgadito virus (CADV) and Maporal virus (MAPV) were isolated from 25 (8.9%) of the 280 rodents captured on farms in 1997 in western Venezuela. The results of analyses of laboratory and zoographic data indicated that Alston's cotton rat (Sigmodon alstoni) is the principal host of CADV, horizontal virus transmission is the dominant mode of CADV transmission in Alston's cotton rat in nature, a pygmy rice rat (Oligoryzomys sp.) is the principal host of MAPV, and the natural host relationships of CADV and MAPV are highly specific.

Referencias de hábitat de Sigmodon alstoni y Zygodontomys brevicauda (Rodentia, Cricetidae) en agroecosistemas de los Llanos de Venezuela / Habitat preferences of Sigmodon alstoni and Zygodontomys brevicauda (Rodentia, Cricetidae) in agroecosystems of the Venezuelan Plains

Se estudiaron las preferencias de hábitat de Sigmodon alstoni y Zygodontomys brevicauda en agroecosistemas de los llanos venezolanos. Se realizó un esfuerzo de muestreo correspondiente a 37748 trampas Sherman. Se capturaron 1624 especímenes de S. alstoni y 1398 de Z. brevicauda. Se determinó que poseen preferencias de hábitat similares. Los cultivos mecanizados, principalmente sorgo y maíz, y los pastizales, constituyeron los hábitat más importantes. Al considerar el eje temporal, se detectó que S. alstoni está más asociado y utiliza con mayor homogeneidad los cultivos mecanizados, seguido en orden de importancia por pastizales y vegetación herbácea. En cuanto a Z. brevicauda, los cultivos mecanizados son primordiales y utiliza los pastizales con menor regularidad, pero mayor homogeneidad. Se asocia intensamente a la vegetación herbácea en breves lapsos de tiempo. Debido a que son vectores de la fiebre hemorrágica venezolana y probablemente otras enfermedades, es necesario monitorear la abundancia poblacional de estos roedores, con el objeto de aplicar medidas de control. De acuerdo con los resultados obtenidos, las estrategias deben estar dirigidas hacia el manejo del hábitat y de las comunidades humanas, sustentadas en programas de educación ambiental, formal e informal, con el fin de disminuir y evitar el contacto del hombre con el roedor.

Maporal virus, a hantavirus associated with the fulvous pygmy rice rat (Oligoryzomys fulvescens) in western Venezuela.

Oryzomine rodents in the southeastern United States, Panama, and southern South America are natural hosts of 6 of the 13 viruses known to cause hantavirus pulmonary syndrome. The purpose of this study was to extend our knowledge of the geographical distribution and genetic diversity of the hantaviruses associated with oryzomine rodents in South America. An infectious hantavirus was isolated from two fulvous pygmy rice rats captured in western Venezuela. Analyses of complete nucleocapsid protein and glycoprotein precursor sequences indicated that the isolates are strains of a novel hantavirus (proposed name "Maporal") which is phylogenetically most closely related to the viruses known to cause hantavirus pulmonary syndrome in southern South America.

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.