Abstract. Eastern equine encephalitis virus (EEEV), the sole species in the EEE antigenic complex, is divided into North and South American antigenic varieties based on hemagglutination inhibition tests. Here we describe serologic and phylogenetic analyses of representatives of these varieties, spanning the entire temporal and geographic range available. Nucleotide sequencing and phylogenetic analyses revealed additional genetic diversity within the South American variety; 3 major South/Central American lineages were identified including one represented by a single isolate from eastern Brazil, and 2 lineages with more widespread distributions in Central and South America. All North American isolates comprised a single, highly conserved lineage with strains grouped by the time of isolation and to some extent by location. An EEEV strain isolated during a 1996 equine outbreak in Tamaulipas State, Mexico was closely related to recent Texas isolates, suggesting southward EEEV transportation beyond the presumed enzootic range. Plaque reduction neutralization tests with representatives from the 4 major lineages indicated that each represents a distinct antigenic subtype. A taxonomic revision of the EEE complex is proposed.Eastern equine encephalitis virus (EEEV) has been recognized as an important veterinary pathogen since the early nineteenth century, when the first clinical descriptions consistent with EEE were reported.
Newcastle disease, one of the most important health problems that affects the poultry industry around the world, is caused by virulent strains of Newcastle disease virus. Newcastle disease virus is considered to be endemic in several countries in the Americas, including Mexico. In order to control Newcastle disease outbreaks and spread, intensive vaccination programs, which include vaccines formulated with strains isolated at least 60 years ago, have been established. These vaccines are dissimilar in genotype to the virulent Newcastle disease viruses that had been circulating in Mexico until 2008. Here, 28 isolates obtained between 2008 and 2011 from different regions of Mexico from free-living wild birds, captive wild birds, and poultry were phylogenetically and biologically characterized in order to study the recent epidemiology of Newcastle disease viruses in Mexico. Here we demonstrate that, until recently, virulent viruses from genotype V continued to circulate and evolve in the country. All of the Newcastle disease viruses of low virulence, mostly isolated from nonvaccinated free-living wild birds and captive wild birds, were highly similar to LaSota (genotype II) and PHY-LMV42 (genotype I) vaccine strains. These findings, together with the discovery of two virulent viruses at the Mexican zoo, suggest that Newcastle disease viruses may be escaping from poultry into the environment.
Endemic circulation of foot-and-mouth disease (FMD) in Africa and Asia poses a continuous risk to countries in Europe, North America, and Oceania which are free from the disease. Introductions of the disease into a free region have dramatic economic impacts, especially if they are not detected at an early stage and controlled rapidly. However, farmers and veterinarians have an obvious disincentive to report clinical signs that are consistent with FMD, due to the severe consequences of raising an official suspicion, such as farm-level quarantine. One way that the risk of late detection can be mitigated is offering non-discriminatory exclusion testing schemes for differential diagnostics, wherein veterinarians can submit samples without the involvement of the competent authority and without sanctions or costs for the farmer. This review considers the benefits and limitations of this approach to improve the early detection of FMD in free countries and gives an overview of the FMD testing schemes currently in use in selected countries in Europe and the Americas as well as in Australia.
Seroconversion to VSNJV was more likely in dairy cattle in southern Mexico located at high elevations than in dairy cattle located at low elevations. These findings should contribute to understanding the dynamics of VSNJV infection in endemic areas and should be useful in the design of effective preventive and control strategies to decrease the impact of future VSV incursions.
RESUMENEl presente estudio se diseñó para mejorar el sistema de vigilancia de las enfermedades vesiculares en México, bajo el sistema de planeación estratégica, identificando las zonas endémicas a través de la estabilidad de linajes virales del serotipo Nueva Jersey, y analizando epidemiológicamente la información generada en 32 años de vigilancia e investigación. Se presentan los resultados que permitieron caracterizar epidemiológicam ente las áreas donde se mantiene el virus de estomatitis vesicular de manera secular en México, y con ello, los componentes necesarios para la construcción de la Matriz de Indicadores para Resultados (MIR) para e l programa de vigilancia de las enfermedades vesiculares en México, que pueden también servir para otros países afectados por esta enfermedad. Adicionalmente se aportan elementos para la prevención de la enfermedad, así como mejorar el comercio internacional de animales de países endémicos de estomatitis vesicular. ABSTRACTThe present study aims to improve the surveillance system of vesicular diseases in Mexico, using the strategic planning system, by identifying endemic areas in which the New Jersey serotype viral lineages are stable and by analyzing the information generated during 32 yr of monitoring. The study shows the necessary elements for building the Matrix of Results Indicators (MRI) that could be used on the vesicular diseases surveillance program in Mexico and in other affected countries. The results that allowed the characterization of the epidemiological areas where the virus of vesicular stomatitis (VS) remains in a secular way in Mexico are presented. Elements for disease prevention are also provided in order to improve the live animal international trade.
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