TESE CARON-corrig. pos defesa- 08-12-10 -PDF.pdf - Universidade ...

ABSTRACT
Influenza is the most frequently studied and anticipated re-emerging disease in
the whole world, mainly because of the historical significance of its occurrences.
The virus that causes it belongs to the Orthomyxoviridae family and infects
many animal species. It is present in aquatic birds in the whole world and finds
in pigs the possibility of undergoing intense mutations, thus raising the concern
about its being a source for potential pandemic viruses. Monitoring viral
circulation is a necessary strategy for an early identification of outbreaks and for
guiding efficient control measures to ensure not only human safety – minimizing
contamination risks – but also the excellence of Brazil as a major poultry and
swine producing and exporting country. The present work was carried out
aiming at contributing to the knowledge of prevalence rates and subtypes of the
virus present in pigs. In order to answer this question, 675 samples of sera from
5327 total pigs were analyzed to study antibodies and to determine the
seroprevalence against subtype H3N2 influenza by the hemagglutination
inhibition test. The animals derived from different areas and growing systems in
the State of Parana – Brazil. Another step in the study sought to identify the
presence of the virus in tissue samples from the respiratory tract of pigs in the
slaughterhouse. First the inoculation of the material was performed in
embryonated eggs, followed by its molecular identification by RT-PCR, for gene
7, which encodes protein M - well preserved in type A viruses. Evaluation
showed that the highest prevalence occurs when there is a high population
density favoring the maintenance of the virus in the population (24% to farm
animals and 3% to run). Likewise, regions characterized by colder climate
proved to predispose the infection in swine more than other regions (ranged of
2,5% at 45%). Five out of the seventy studied samples were positive for the
type A virus. The presence of virus in 7,15% of samples denoting the presence
of the virus in swine livestocks studied, reinforcing the need for active
monitoring using sensitive tests that allow managing the potential occurrence
risk of the disease in Brazil.
Key-words: influenza, sero-epidemiology, RT-PCR, H3N2, population density.
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