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標(biāo)題: Swine Influenza Virus (SI), Flu [打印本頁]

作者: 朱春明    時間: 2009-4-9 14:30
標(biāo)題: Swine Influenza Virus (SI), Flu
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Swine influenza is caused by a number of closely related influenza A viruses that are noted for their ability to change their antigenic structure and create new strains. Each serotype is identified by surface proteins referred to as "H" and "N". The three common strains that affect the pig are described as H1 N1, H1 N2 and H3 N2. There are also different strains within these serotypes with differing pathogenicity (capacity to produce disease). The incubation period of the disease is very short, as little as 12-48 hours and the onset is usually rapid and dramatic. It is virtually impossible to maintain a population of pigs that is influenza virus free. SI in large herds may become endemic with intermittent bouts of disease and infertility and different strains may also sequentially infect the herd. Immunity to influenza viruses is often short lived (6 months) and the immunity profile in the breeding herd varies considerably with time.



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SymptomsPiglets Sows When the virus first enters the herd two or three animals may be observed sick for the first two days, followed by: At a herd level the following may also be seen: Weaners & Growers Acute disease: Endemic disease: Causes / Contributing factorsSI can be introduced by: DiagnosisThis can often be made reliably on clinical grounds with acute disease because there are no other diseases that are so dramatic in their onset and clinical effects. No other disease affects so many pigs so quickly. Blood samples taken at the time of onset of disease from affected sows and repeated 2-3 weeks later show rising levels of antibody to the specific virus. SIV can be readily grown from nasal and throat swabs and identified in the laboratory. This is often the best approach to confirm the diagnosis. In acute disease the spread is so dramatic across all ages that little else can be confused with it. In endemic disease however differentiation from other viral infections can be difficult, but PRRS, PRCV, AD and also erysipelas should be considered.

Further ReadingClick on the links below to find out more about this disease, including treatment, management control and prevention information. The top link is the main article on this disease.
作者: htshan001    時間: 2009-5-20 22:25
study it,thank you very much
作者: kimdaejung    時間: 2009-5-22 12:36
這篇文章的出版時間應(yīng)該比較早了,因?yàn)槭澜缧l(wèi)生組織從3月底開始已經(jīng)廢棄了Swine Influenza這種說法。




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