| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 92 === The “fowl plague”, now known to be caused by highly virulent influenza virus, was first described in 1878 as a disease affecting chickens in Italy. It was not identified as virus until 1901. Schafer demonstrated that fowl plague virus was a member in the influenza A virus group (H7N7) in 1955. Afterward, it was defined as “highly pathogenic avian influenza” (HPAI) at International Avian Influenza Assembly in 1981. There were 21 cases of HPAI reported connecting with poultry from 1959 to 2003. The H5N1 avian influenza virus spread and caused severe economic damage among Asia countries in 2004. The avian influenza virus (AIV) was isolated in Hong Kong outbreak in 1997 and caused 6 deaths in 18 cases, which were confirmed direct-transmitting to human without through intermediate hosts. It also happened and caused fatality in Netherlands in 2003 and in Vietnam and Thailand in 2004. Avian influenza viruses (AIV), belonging to the Orthomyxoviridae, have eight segments of single-stranded RNA molecules which are contained within the viral envelope, and AIV is classified as different subtypes based on the antigenic differences of composition of amino acid in their Hemagglutinin (HA) and Neuraminidase (NA). HA and NA were classified from H1 to H15 and from N1 to N9 depending on their antigencity difference. AIV is stable in pH 7.0-8.0, sensitive to acidic and basic environment, while under pH 3.0 or over pH 9.0 is easy to die out. The AIV will be vanished after heating 3 hours at 56°C, 30 minutes at 60°C, or 1 minute at 100°C. The antigenicity of AIV changes easily by genetic reassortment. The composition of amino acid near the cleavage site of HA are different which made by the different subtypes of AIV. The infectivity will increase to 5 to 200 times after HA of AIV being cleaved by specific proteases.
The having known AIV are all A type influenza virus, which is able to transmit to mammals. The typical symptoms of poultry infected with AIV appeared raffled feathers, listlessness, depression, cessation of egg laying, diarrhea, cyanosis of the combs and wattles, swelling around the eyes, etc. While human infecting with AIV, he will suffer from the similar symptoms of other influenza like fever, prostration, cough, sore throat and conjunctivitis. If worse, it may lead to viral pneumonia, respiratory and other organs distress, or even death. The hosts of AIV include wild bird, waterfowl, chicken, duck, turkey and some mammals like equine, seal, and swine. The wild birds excrete to highly-level-viruses in feces. Many poultry are infected with AIV by contacting the wild bird’s feces or the water resources which are contaminated by the feces from wild bird. The AIV may spread to hatched chick through the eggs and artificial fertilization. The indirect viruses carriers like workers, equipment, and vehicles also may transmit AIV to poultry. The outbreaks of AIV in poultry have led to severe economic damages in many countries for many years. The imbalance supply of poultry products caused an upswing the price of poultry markets. People could not or even did not dare to consume poultry any more. It has made a great impact of poultry industries and the management of food sanitation. This study proposed appropriate sanitary measures which based on collecting materials mentioned. The government should consider timely monitor the AIV situation on wild birds and poultry. The living poultry wholesale, retail markets and poultry house should keep alert on their environmental sanitation. When the highly pathogenic avian influenza breaks out, immediately actions including stamp out and demolish the infected poultry, as well as check and control related people and vehicles. For the sanitation of food, measures as prohibit importing poultry and poultry products from epidemic area, periodically shut down and sterilize
the living poultry markets, and enforce the sanitation inspection to traditional and wholesale slaughter stalls. Furthermore, extending efforts as urge the owners of restaurants to use the legitimate poultry, select washing table eggs or cook eggs after suitable washing, and serve to customers only after the poultry meat, eggs, and viscera food were boiled enough. For the prevention of human infection with AIV, works such as strengthen public propaganda of AIV characteristics, persuade people to do self-defending and apply vaccination to the highly risk potential people at appropriate time.
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