RESUMO
A regional prospective study of the epidemiology of bluetongue virus (BTV) serotypes covering 11 countries in Central America and the Caribbean took place between 1987 and 1992. Active surveillance revealed BTV infection to be endemic in the absence of confirmed indigenous cases of bluetongue. During the 6-year span of the study, over 300 BTV isolations were obtained from cattle and sheep. Results of the earlier years of the study were summarized, and surveillance activities in the concluding months of the study from November 1990 to February 1992 were evaluated. Forty-five BTV isolations were made during this time, 44 from sentinel cattle and 1 from a ram with clinical signs compatible with contagious ecthyma. Virus isolation from potential vectors also was attempted, yielding a further 9 BTV isolates from parous Culicoides insignis and C pusillus, 2 BTV isolates from blood-engorged C filarifer, and 1 epizootic hemorrhagic disease virus type-2 isolate from parous C pusillus. Our extensive network of sentinel herds in the region detected BTV-1 as the predominant serotype in Central America in 1991, after an apparent absence of 1 year in the sentinel animals. Other serotypes in Central America at that time included BTV-3 and BTV-6. In Puerto Rico and the Dominican Republic, BTV-4 became the predominant serotype, without detection of BTV-8 and BTV-17, which were common in recent years of the study. The serotypes found in the Caribbean Basin continued to have marked differences from those in North America. The importance of viewing bluetongue as an infection, the distribution of which is determined principally by ecologic factors, is emphasized.
Assuntos
Vírus Bluetongue/isolamento & purificação , Bluetongue/epidemiologia , Ceratopogonidae/microbiologia , Ruminantes/microbiologia , Animais , Bluetongue/sangue , Bluetongue/microbiologia , Vírus Bluetongue/classificação , Região do Caribe/epidemiologia , Bovinos , Doenças dos Bovinos , América Central/epidemiologia , Embrião de Galinha , Estudos ProspectivosRESUMO
Forty-four species of Culicoides (Diptera: Ceratopogonidae) were caught in insect light traps during the first 2 years of studies on the epidemiology of bluetongue virus in the Caribbean and Central America. Traps were operated near sentinel ruminants which were bled monthly for serologic evaluation and then virus isolation. More than 570,000 individuals were identified. Culicoides insignis Lutz accounted for 90% of the catch, C. filarifer Hoffman/C. ocumarensis Ortiz 5%, C. furens Poey 3% and C. pusillus Lutz 2%. Other species accounted for less than 1% of the total catch. Sentinel ruminants became seropositive when C. insignis populations were high at many study sites. At a few sites C. pusillus and C. filarifer/C. ocumarensis were predominant or were present in large numbers during seroconversions of sentinels. Virus isolations were obtained from sentinel ruminants during times when these same species were present in large populations.
Assuntos
Bluetongue/epidemiologia , Ceratopogonidae/microbiologia , Insetos Vetores/microbiologia , Ruminantes , Animais , Anticorpos Antivirais/sangue , Bluetongue/diagnóstico , Bluetongue/transmissão , Vírus Bluetongue/imunologia , América Central/epidemiologia , Feminino , Masculino , Índias Ocidentais/epidemiologiaRESUMO
A study of the epidemiology of bluetongue viruses is in progress with the collaboration of 11 Central American and Caribbean countries. To date, over 200 bluetongue virus isolates have been obtained from cattle and sheep in sentinel groups distributed in the participating countries. Bluetongue serotypes identified include 1, 3, 6, and 12, virus types not previously recorded in the Western Hemisphere. Although the clinical impact of bluetongue virus infections in this hyperendemic environment appears to be minimal, the ubiquity of infection causes restrictions on the export of ruminant livestock and germ plasm. The stability of the Caribbean region ecosystem and the long-range implications of the interface with the northern temperate bluetongue virus ecosystem are reviewed.
Assuntos
Bluetongue/epidemiologia , Doenças dos Bovinos/epidemiologia , Doenças dos Ovinos/epidemiologia , Clima Tropical , Animais , Bovinos , América do Norte/epidemiologia , Ovinos , América do Sul/epidemiologiaRESUMO
Results of a prospective serologic and virologic study of ruminant livestock in Central America and the Caribbean islands revealed bluetongue virus (BTV) to be enzootic in the 9 countries participating in the study. Bluetongue virus serotypes 1, 3, 6, and 12 were isolated from sentinel animals. To the authors' knowledge, these are the first isolations of BTV from the region studied and the first isolations of these serotypes in the Western Hemisphere. Clinical disease attributable to BTV infection was not observed in sentinel animals. The incidence pattern, with respect to age and geographic location, was determined. The need to evaluate the epizootiologic features or arthropod-borne viruses (arboviruses) on a regional ecologic basis is stressed.
Assuntos
Anticorpos Antivirais/análise , Vírus Bluetongue/isolamento & purificação , Bovinos/microbiologia , Reoviridae/isolamento & purificação , Animais , Anticorpos Antivirais/imunologia , Especificidade de Anticorpos , Vírus Bluetongue/classificação , Búfalos/microbiologia , América Central/epidemiologia , Epitopos , Estudos Prospectivos , Distribuição Aleatória , Sorotipagem/veterinária , Ovinos/microbiologia , Fatores de Tempo , Índias Ocidentais/epidemiologiaRESUMO
There is recent evidence of bluetongue (BT) and epizootic haemorrhagic disease (EHD) virus infection of cattle in the American tropics, including BT group reactive antibody in Colombian cattle. These observations prompted a study to determine serologically the specific BT and EHD virus types present, and time of infection and to collect Culicoides spp. as potential vectors. A prospective study of BT and EHD virus infection was done on two farms in the Colombian department of Antioquia. Sequential sampling of young cattle indicated acquisition of neutralizing antibody to BT virus serotypes 12, 14 and 17, and EHD virus serotypes 1 and 2. Insect captures showed a high association of Culicoides insignis with infected cattle.
Assuntos
Vírus Bluetongue/classificação , Bluetongue/microbiologia , Doenças dos Bovinos/microbiologia , Infecções por Reoviridae/veterinária , Reoviridae/classificação , Animais , Anticorpos Antivirais/análise , Bluetongue/epidemiologia , Vírus Bluetongue/imunologia , Bovinos , Doenças dos Bovinos/epidemiologia , Ceratopogonidae , Colômbia , Cervos , Feminino , Insetos Vetores , Testes de Neutralização , Testes de Precipitina , Reoviridae/imunologia , Infecções por Reoviridae/epidemiologia , Infecções por Reoviridae/microbiologia , Sorotipagem , OvinosRESUMO
The ability of Simulium mexicanum and Simulium metallicum to serve as biological or mechanical vectors of an enzootic and an epizootic strain of Venezuelan equine encephalitis (VEE) virus was examined. Guinea pigs were inoculated with the epizootic Cordoba strain or the enzootic RPVP407 strain of VEE virus. Wild-caught adult Simuliidae were fed on the viremic guinea pigs and the virus content of groups of flies was determined at daily intervals post-engorgement to test for viral replication. Flies were refed on suckling mice at greater than or equal to 8 days post-engorgement to test for biological transmission. Other flies were interrupted while feeding on viremic guinea pigs and refed on suckling mice to test for mechanical transmission. Neither S. mexicanum nor S. metallicum appear to be efficient vectors of either strain of VEE virus, although occasional mechanical transmission was obtained. Titers of virus in flies decreased rapidly after engorgement and from 3-12 days post-engorgement virus was detected only in 5%-25% of both species of flies. Although earlier field evidence implicated both S. mexicanum and S. metallicum as vectors of epizootic VEE, we conclude that it is highly unlikely that they play an important role as vectors of the virus in nature.
Assuntos
Encefalomielite Equina/transmissão , Encefalomielite Equina Venezuelana/transmissão , Simuliidae/microbiologia , Animais , Colômbia , Vírus da Encefalite Equina Venezuelana/fisiologia , Encefalomielite Equina Venezuelana/microbiologia , Comportamento Alimentar , Cobaias , Masculino , Camundongos , Simuliidae/fisiologiaRESUMO
Recent evidence of bluetongue (BT) virus infection of livestock in scattered localities in the neotropics prompted a serologic survey of cattle in Colombia and Costa Rica. In Costa Rica 48.1% of 1435 bovine animals had BT virus antibody in the agar gel precipitation test (AGPT). In Colombia 51.8% of 635 cattle were AGPT-positive for BT virus. Antibody prevalence ranged from over 50% in the lowlands to 0% in Costa Rica and 19% in Colombian cattle above 2000 m altitude. Neutralization tests indicated that Costa Rican cattle had been exposed to BT virus types 6, 12, 14 and 17.
Assuntos
Anticorpos Antivirais/análise , Vírus Bluetongue/imunologia , Bluetongue/epidemiologia , Doenças dos Bovinos/epidemiologia , Reoviridae/imunologia , Altitude , Animais , Bovinos , Colômbia , Costa Rica , Imunodifusão , Testes de Neutralização , OvinosRESUMO
Bluetongue virus (BTV) group antibodies are widely distributed in Costa Rica and Northern Colombia; prevalence is highest at lowest altitudes. Clinical evidence of bluetongue (BT) infection in cattle is not seen. Evidence exists of the circulation of BTV serotypes 6 and 14 in Costa Rica and BTV serotype 12, 14 and 17 in Northern Colombia in the period 1981-1983. Culicoides insignis is implicated as a probable vector in Colombia.