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Bast, T. F., Whitney, E., & Benach, J. L. (1973). Considerations on the ecology of several arboviruses in eastern Long Island. Am J Trop Med Hyg, 22(1), 109–115.
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Sudia, W. D., Fernandez, L., Newhouse, V. F., Sanz, R., & Calisher, C. H. (1975). Arbovirus vector ecology studies in Mexico during the 1972 Venezuelan equine encephalitis outbreak. Am J Epidemiol, 101(1), 51–58.
Abstract: Virus vector studies were conducted in the States of Durango, Chihuahua, and Tamaulipas, Mexico, in June and July 1972. Apparently only a low level of Venzuelan equine encephalitis (VEE) virus transmission to equines occured at the time of the study, and the infection was restricted to areas which had not experienced overt activity during the preceding year. The low level of infection was associated with a scarcity of mosquitoes. The IB (epidemic) strain of VEE virus was isolated from two pools of Anopheles pseudopunctipennis (Theo.) and the blood of one symptomatic equine. The low mosquito population, the relatively few equine cases observed, and the absence of reports of VEE human disease from the outbreak area suggested VEE virus persistence through a low-level mosquito-equine transmission cycle. Other studies have already indicated that wild vertebrates play no more than a minor role in outbreaks of epidemic VEE. Mosquito collections made in areas of the states of Durango, Chihuahua, and Tamaulipas, where considerable epidemic activity of VEE had occurred in 1971, failed to reveal evidence of VEE virus persistence. Twenty-nine ioslations of other arboviruses were also made in these studies: including 22 of St. Louis encephalitis virus (SLE), 2 of Flanders virus, 1 of Turlock virus, 1 of Trivittatus virus of the California Group, 1 of western equine encephalitis virus (VEE), and 2 (from Santa Rose) which possibly represent a hitherto unknown virus in the Bunyamwera Group. These are the first reports of SLE virus isolations from mosquitoes in Mexico, and the first demonstration of Trivittatus, VEE Turlock and Flanders viruses in Mexico from any source.
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Mitchell, C. J., Darsie, R. F. J., Monath, T. P., Sabattini, M. S., & Daffner, J. (1985). The use of an animal-baited net trap for collecting mosquitoes during western equine encephalitis investigations in Argentina. J Am Mosq Control Assoc, 1(1), 43–47.
Abstract: A large net trap was used to sample mosquito populations attracted to horses at three sites each in Santa Fe and Rio Negro Provinces, Argentina, during the austral summer of 1984. These provinces, as well as others in Argentina, were affected by a severe epizootic of western equine encephalitis (WEE) during 1982-83. Totals of 2,752 and 6,929 mosquitoes were collected in Santa Fe and Rio Negro Provinces during five and three trap nights, respectively. Culex mosquitoes of the subgenus Culex were predominant (45.8% of total) in the Santa Fe collections, although Aedes albifasciatus also was prevalent (21.7%). The latter species was predominant (95.7% of total) in the Rio Negro collections. The mosquito fauna was less complex (minimum of 6 species) in Rio Negro Province as compared to Santa Fe Province (minimum of 18 species). The advantages of the net trap indicate that this trap can become a useful tool in arbovirus ecology studies in other areas.
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Sabattini, M. S., Monath, T. P., Mitchell, C. J., Daffner, J. F., Bowen, G. S., Pauli, R., et al. (1985). Arbovirus investigations in Argentina, 1977-1980. I. Historical aspects and description of study sites. Am J Trop Med Hyg, 34(5), 937–944.
Abstract: This is the introductory paper to a series on the ecology of arboviruses in Argentina. Epizootics of equine encephalitis have occurred since at least 1908, principally in the Pampa and Espinal biogeographic zones, with significant economic losses; human cases of encephalitis have been rare or absent. Both western equine and eastern equine encephalitis viruses have been isolated from horses during these epizootics, but the mosquitoes responsible for transmission have not been identified. A number of isolations of Venezuelan equine encephalitis (VEE) virus were reported between 1936 and 1958 in Argentina, but the validity of these findings has been seriously questioned. Nevertheless, serological evidence exists for human infections with a member of the VEE virus complex. Serological surveys conducted in the 1960s indicate a high prevalence of infection of humans and domestic animals with St. Louis encephalitis (SLE), and 2 SLE virus strains have been isolated from rodents. Human disease, however, has rarely been associated with SLE infection. Only 7 isolations of other arboviruses have been described (3 of Maguari, 1 of Aura, 2 of Una, and 1 of an untyped Bunyamwera group virus). In 1977, we began longitudinal field studies in Santa Fe Province, the epicenter of previous equine epizootics, and in 1980 we extended these studies to Chaco and Corrientes provinces. The study sites are described in this paper.
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Hardy, J. L. (1987). The ecology of western equine encephalomyelitis virus in the Central Valley of California, 1945-1985. Am J Trop Med Hyg, 37(3 Suppl), 18s–32s.
Abstract: Reeves' concept of the summer transmission cycle of western equine encephalomyelitis virus in 1945 was that the virus was amplified in a silent transmission cycle involving mosquitoes, domestic chickens, and possibly wild birds, from which it could be transmitted tangentially to and cause disease in human and equine populations. Extensive field and laboratory studies done since 1945 in the Central Valley of California have more clearly defined the specific invertebrate and vertebrate hosts involved in the basic virus transmission cycle, but the overall concept remains unchanged. The basic transmission cycle involves Culex tarsalis as the primary vector mosquito species and house finches and house sparrows as the primary amplifying hosts. Secondary amplifying hosts, upon which Cx. tarsalis frequently feeds, include other passerine species, chickens, and possibly pheasants in areas where they are abundant. Another transmission cycle that most likely is initiated from the Cx. tarsalis-wild bird cycle involves Aedes melanimon and the blacktail jackrabbit. Like humans and horses, California ground squirrels, western tree squirrels, and a few other wild mammal species become infected tangentially with the virus but do not contribute significantly to virus amplification.
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