禽場空氣中禽流感病毒之濃度分布

Concentration distribution of airborne avian influenza virus in poultry farm

王瑞甫(Rui-Fu Wang)

指導教授 ： 陳培詩

高雄醫學大學/健康科學院/公共衛生學系公共衛生學碩士班/碩士(2019年)

摘要

研究背景
禽流感在台灣畜牧業造成強烈的衝擊，目前雖然人的案例很少多半也都是境外的案例，但仍然是一重大的風險，現行的防疫方式似乎無法有效預防或降低禽流感的爆發，過去研究指出糞口傳播、口對口傳播或是空氣傳播都是重要的傳播途徑之一，但台灣在空氣中禽流感病毒的資訊還很少，對於空氣中禽流感病毒監測及傳播的預防與控制的了解有限。
研究目的
本研究主要目的為(1)禽類案例場進行空氣中禽流感病毒定量，(2)對一般的禽場進行長時間的空氣中禽流感病毒定量，了解空氣中禽流感病毒濃度隨時間變化的趨勢及其影響因子(3)探討空氣中禽流感病毒監測對於傳播的預防與控制可能的應用。
研究方法
本研究於2017年11月至2019年1月進行雲林各個案例場的空氣監測，於2017年5月至2018年8月進行一般禽場的空氣中禽流感病毒濃度的長期監測。使用filter(Teflon)、impinger，進行空氣樣本的收集，並利用Real-time qPCR分析其濃度，同時收集環境測站的環境因子(溫度、濕度、風速)，隨後利用統計軟體分析環境因子與病毒濃度之相關性。
研究結果
禽流感案例場
在半開放式水禽場的禽隻活動區採集到平均濃度為9.5x104±1.1x105copies/m3，並且在開放式的水禽場採樣結果皆為N.D.，陸禽場禽隻活動區最高平均濃度為1.7x105±1.9x105 copies/m3。在撲殺前，陸禽場在禽隻數量、禽場面積、死亡率為顯著正相關，濕度為顯著負相關；水禽場在禽場面積為顯著負相關，禽隻密度、風速為顯著正相關，撲殺後，病毒濃度與風速為顯著正相關。
長期監測場
第一批次最高濃度為5.8x1012copies/m3，第二批次最高濃度為3.7x105copies/m3，第三批次皆為N.D.，在有症狀的同時也都有高濃度的產生，並且在環境消毒後濃度也隨之下降。
結論
本研究中採樣方法的結果，對於禽流感傳播的預防及控制，在半密閉空間、禽隻密度高及採樣時間長的條件下有一定的可行性，未來在開闊場域的環境採樣仍需再改善。環境因子中的風速在案例場及長期監測場都與病毒濃度呈顯著的正相關。

關鍵字

禽流感 ； 禽場 ； 空氣傳播

並列摘要

Background:
Avian influenza has had a strong impact on poultry industry in Taiwan. Nowadays, there are few human cases and most of them were overseas, however it is still a huge hazard. It seemed that the current methods of epidemic prevention neither prevent effectively nor control the outbreaks. There are some studies have pointed out that fecal-oral, mouth-to-mouth and mouth-to-nose are important routes of infection. However, there is little information about airborne avian influenza in Taiwan, so it is a limitation to surveillance, prevention and control airborne avian influenza.

Aim:
Monitor and quantify concentration of avian influenza virus in the air in the poultry farms which were outbreak. We quantified of avian influenza virus in the air for a long time in the general poultry farm, and observed the trend of avian influenza virus concentration in the air over time and its effect factors.

Methods:
The period of outbreak poultry farms was from November 2017 to January 2019, and the period of the general poultry farm was from May2017 to August 2018. Each air sample was collected by 37 mm polypropylene filter cassette with a Teflon filter and impinger. All samples were analyzed by real-time qPCR for quantitative analysis, while we collected environmental factors, including temperature, humidity and wind speed, which were provided by Taiwan Environmental Protection Administration.

Results:
Outbreak poultry farms
The average concentration of the semi-open waterfowl farms was 9.5x104±1.1x105 copies/m3, and the results in the free range waterfowl farm were all ND. The average concentration of the land fowls farms was 1.7x105 ±1.9x105 copies/m3. For correlation test, in land fowls farms before culling, it’s significantly positive correlated with poultry numbers, area, and the mortality rate, while humidity is significantly negative correlated. Furthermore, in waterfowl farms before culling, it’s significantly positive correlated with density and wind speed, while it’s significantly negative correlated with wind speed. However, the concentration of virus is significantly positively correlated with wind speed after culling.

General poultry farm
The highest concentration of the first batch is 5.8x1012copies/m3, the second batch is 3.7x105copies/m3, and the third batch is all N.D. When poultry developed symptoms, we also detected much higher concentration. And after disinfection, the concentration decreased.

Conclusions:
The results in our study which are feasible to prevent and control the transmission of avian influenza when the farm is semi-opened, high density and long-sampling time. Nevertheless, it still needs to be improved in the free-range farm in the future. We also find that wind speed, one of meteorological factors, is significantly positive correlated with the virus concentration in both outbreak farm and general farm.

並列關鍵字

Avian influenza virus ； poultry farm ； airborne

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