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Alexander, D. J. (1982). Ecological aspects of influenza A viruses in animals and their relationship to human influenza: a review. J R Soc Med, 75(10), 799–811.
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Barwick, R. S., Mohammed, H. O., McDonough, P. L., & White, M. E. (1998). Epidemiologic features of equine Leptospira interrogans of human significance. Prev Vet Med, 36(2), 153–165.
Abstract: Leptospirosis is a zoonotic bacterial disease caused by Leptospira interrogans. There is a serologic evidence that horses are exposed to L. interrogans and, as a shedder of these organisms, can be a threat to humans. We examined risk factors associated with the risk of testing seropositive to three L. interrogans serovars (L. icterohaemorrhagiae, L. grippotyphosa, and L. canicola) in the horses of New York State, in order to understand the epidemiology of the disease and suggest strategies to control and prevent equine leptospirosis. To carry out this study, blood samples were collected from a random sample of 2551 horses and tested for the presence of antibodies to the above serovars using the microscopic agglutination test. Samples with a titer $100 were considered positive. Clinical and demographic data were collected on each horse, the farms' management practices and ecology. Logistic regression analysis was used to develop a multivariate indexing system and to identify factors significantly associated with the risk of leptospirosis. Four indices were developed based on the possible sources of exposure: rodent exposure index; wildlife exposure index; soil and water index; and management index. The soil and water index was significantly associated with the risk of exposure to all three serovars. Management was positively associated with L. icterohaemorrhagiae and L. canicola. Density of horses turned out together was positively associated with the risk of exposure to L. grippotyphosa. We concluded that indirect exposure of horses to L. interrogans through contaminated soil and water appears to be significantly associated with the risk of exposure to all three serovars. Management appears to play an important role in the exposure to L. interrogans. Modification of management practices might reduce the horses' risk of exposure and hopefully minimize the human hazards.
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Beveridge, W. I. (1993). Unravelling the ecology of influenza A virus. Hist Philos Life Sci, 15(1), 23–32.
Abstract: For 20 years after the influenza A virus was discovered in the early 1930s, it was believed to be almost exclusively a human virus. But in the 1950s closely related viruses were discovered in diseases of horses, pigs and birds. Subsequently influenza A viruses were found to occur frequently in many species of birds, particularly ducks, usually without causing disease. Researchers showed that human and animal strains can hybridise thus producing new strains. Such hybrids may be the cause of pandemics in man. Most pandemics have started in China or eastern Russia where many people are in intimate association with animals. This situation provides a breeding ground for new strains of influenza A virus.
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Kida, H. (1997). [Ecology of influenza viruses in animals and the mechanism of emergence of new pandemic strains]. Nippon Rinsho, 55(10), 2521–2526.
Abstract: Ecological studies on influenza viruses revealed that the hemagglutinin genes are introduced into new pandemic strains from viruses circulating in migratory ducks through domestic ducks and pigs in southern China. Experimental infection of pigs with 38 avian influenza virus strains with H1-H13 hemagglutinins showed that at least one strain of each HA subtype replicated in the upper respiratory tract of pigs. Co-infection of pigs with a swine virus and with an avian virus generated reassortant viruses. The results indicate that avian viruses of any subtype can contribute genes in the generation of reassortants. Virological surveillance revealed that influenza viruses in waterfowl reservoir are perpetuated year-by-year in the frozen lake water while ducks are absent.
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Stout, I. J., Clifford, C. M., Keirans, J. E., & Portman, R. W. (1971). Dermacentor variabilis (Say) (Acarina: Ixodidae) established in southeastern Washington and northern Idaho. J Med Entomol, 8(2), 143–147.
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