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Title: | 2005至2007年台灣與金門地區活禽市場與家禽工作業者
對家禽流行性感冒病毒的病毒與血清學偵測 Virological and Serological Surveillance of Avian Influenza Viruses in Live-Bird Markets and Poultry-Related Workers in Taiwan and Kinmen during 2005-2007 |
Authors: | Hsiu-Ping Lin 林琇蘋 |
Advisor: | 金傳春(Chwan-Chuen King) |
Keyword: | 台灣家禽流行性感冒病毒偵測,H5N2,禽畜人員,活禽市場,血清偵測,流行病學,危險因子,禽流感防治, surveillance,live-bird market,epidemiology,multiple subtypes of avian influenza viruses,H5N2,co-circulation,hemagglutinin inhibition test,microneutralization assay,seroprevalence,poultry workers,risk factor,zoonosis,Taiwan, |
Publication Year : | 2007 |
Degree: | 碩士 |
Abstract: | 流行性感冒(簡稱流感)病毒H5N1是自然界理論上共144種流感病毒亞型中,在公共衛生上最重要的亞型,在保護不足、消毒不全的情況下,極易從與禽/鳥不經意的接觸而傳染給人,是人畜共通傳染病。自1997年迄今高致病性禽流感病毒H5N1已在人群中造成30-75%的致死率,多數案例出現於亞洲的養禽業者;未來H5N1病毒仍會持續突變及與其它不同宿主的流感病毒進行基因重組,若進而跨越宿主而感染大量人群,將造成公共衛生的一大夢魘。為此本研究特別在禽類及禽流感易感染的高危險族群中,分別進行病毒偵測與血清偵測,以確保台灣民眾的健康。本研究含兩大部份:(一) 自2005年10月至2006年10月人禽交界的活禽批發市場進行家禽流行性感冒病毒的病毒監測;及(二)自2005年10月至2007年1月收集台灣禽畜相關人員共607隻血清,進行其對台灣低致病性家禽流行性感冒病毒H5N2的血清抗體監測。
作法上,在家禽流行性感冒病毒監測方面,採集禽的糞便檢體1924支,以無特殊病原9~12日齡雞胚胎蛋進行病毒培養,再以對該病毒H1, H2, H4, H5, H6, H7亞型專一的引子經由反轉錄-聚合酶鏈反應(reverse transcriptase polymerase chain reaction, RT-PCR)法進行家禽流行性感冒病毒亞型之鑑別;在人員血清監測上,以自2005年10月本活禽市場家鴨分離的低致病性家禽流行性感冒病毒H5N2 [A/duck/Taiwan/LBM01/2005 (H5N2)]為抗原,以改良的血球凝集抑制試驗與血球凝集抗原(HAU)為1單位篩檢禽畜相關人員血清中此病毒抗體力價,其呈陽性的血清,再以微中和試驗及西方式墨點法進行確認。 本研究的病毒監測發現鴨的家禽流行性感冒病毒分離率(12.02%, 97/807)高於雞的家禽流行性感冒病毒分離率(0.27%, 3/1117, p<0.05),亞型中以H4最多(79%, 79/100),其次為H5(29%, 29/100)、H1 (17%, 17/100)、H6(9%, 9/100)、H2(5%, 5/100)與H7(0%)。此外,整體家禽流行性感冒病毒分離率最高的月份在2006年的2月(33.3%),同月也有兩種以上的家禽流行性感冒病毒同時存於活禽市場中,且以H4及H5亞型居多,各為4%(79/1924)及2%(29/1924)。血球凝集基因的演化樹分析,發現台灣活禽市場鴨低致病性家禽流行性感冒病毒H5亞型彼此間自成一族群,且與自1997至2006年在東南亞國家、美洲、歐洲禽鳥類的高致病性鳥/禽流感病毒H5N1或其他非H5N1的H5病毒均不具演化上的關聯;更重要的是與2003年台灣的低致病性家禽流行性感冒病毒H5N2亦不同,這些證據指出本研究分離的低致病性家禽流行性感冒病毒H5儼然已在台灣落地生根了。 在高危險群血清監測,共搜集607禽畜相關人員(平均年齡為46±11.5歲,男:女=7:3)的血清,以血球凝集抑制法,篩檢其對[A/duck/Taiwan/LBM01/2005(H5N2)]病毒的抗體,發現140位禽畜人員血清對此病毒的抗體力價大於40。扣除抗體力價無變化的配對血清後,總抗體盛行率為23.5% (133/566)。單變項分析顯示禽畜相關人員得到H5感染最主要的危險因子為年齡與職業,年齡在52歲以上及40至52歲者得此H5病毒感染之風險分別是其年齡低於40歲者的3.14倍(95%信賴區間為1.82至5.43;p<0.0001)及1.79倍(95%信賴區間為1.03至3.11;p=0.038);職業暴露中,豬農得此病毒感染的風險最高【勝算比(Odds Ratio, OR)為21.6,95%信賴區間為3.94~118,p<0.0001】;活禽市場工作者次之【勝算比為4.87,95%信賴區間為1.46~16.2,p<0.006】;官方動物疾病控制人員再次之【勝算比為4.33,95%信賴區間為1.14~16.5,p=0.02】;鴨農得到感染的風險也不低【勝算比為3.94,95%信賴區間為1.06~14.6,p=0.03】;雞農比鴨農的風險更低【勝算比為1.66,95%信賴區間為0.45~6.11,p=0.44】。進一步以市場工作者的家人為比較分析工作職責,發現市場清潔工與家禽屠體處理者的危險性皆為2.5倍(95%信賴區間:0.19~32.20,p=0.47及0.21~29.25,p=0.46);而市場販賣者的危險性是2.39倍(95%信賴區間:0.27~21.29,p= 0.42);屠殺家禽人員的危險性是1.82倍(95%信賴區間:0.19~17.19,p= 0.60);其它因子如個人配戴防護裝備頻率、住家附近有動物飼養場、六個月內有購買寵物、一年內出國旅遊及三個月內有類流感症狀等,均不具有統計的顯著差異。 本研究發現台灣的禽畜相關人員已持續多月處於家禽流行性感冒病毒H5的暴露之下,且部份禽畜相關人員已具有家禽流行性感冒病毒H5的抗體。雖現今台灣仍為高致病性禽流感病毒的非疫區,但在中國大陸及東南亞各國疫情不斷延燒的威脅下,且活禽市場具多種家禽流行性感冒病毒亞型同時存在、多種宿主及人禽交界的多項特徵,為保障民眾的健康,因此未來仍需持續追蹤台灣活禽市場內家禽流行性感冒病毒的跨宿主演化潛力及禽畜人員血清中此類病毒的抗體變化,最有效的防疫作為實有賴政府、學界及民眾三方面的坦誠合作,必能杜絕後患。 Since 1997, outbreaks of highly pathogenic avian influenza (HPAI) (H5N1) have continued to occur all over the world. Avian influenza viruses (AIVs) became an emerging zoonostic disease which had caused more than three hundred human cases, and 192 of them died till June 11, 2007. Live-bird market (LBM) was thought as a mixing pool of AIVs and occupational exposure was a potential risk factor for acquiring the infection. In order to establish a systematic surveillance in the avian-human interface, we combined both virological surveillance in one whole-sale LBM in Taiwan during October 2005-October 2006 and serological surveillance among poultry-related workers in Taiwan and Kinmen from October 2005 to January 2007. To evaluate viral evolution of AIVs in LBM, we weekly collected fecal swabs of chickens and ducks from one whole-sale LBM in Taiwan and got 1924 specimens for viral culture using special pathogen free (SPF) chicken embryotic eggs. H1, H2, H4, H5, H6, H7 subtype-specific primers and reverse transcriptase polymerase chain reaction (RT-PCR) were employed to identify the subtypes of the circulating AIVs within LBM. To investigate the potential of cross-species infection of AIVs for poultry-related workers in Kinmen and Taiwan, 607 serum samples from both personnel in LBM and poultry farms were collected. Modified hemagglutinin inhibition test and 1 unit of hemagglutinin (HA) of A/duck/Taiwan/LBM01/2005 (H5N2) isolated from October of 2005 from the same LBM were used for screening first, and then the seropositive samples (HI serotiter>40) were then reconfirmed by different serological tests such as microneutralization assay (MN) and western blot. In virological surveillance, ducks had higher isolation rate of AIVs than that of chickens [12.02% (97/807) vs 0.27% (3/1117), p<0.05]. Among all subtypes, H4 was the highest (79/100, 79%), followed by H5 (29/100, 29%), H1 (17/100, 17%), H6 (9/100, 9%), H2 (5/100, 5%), and no H7 (0/100, 0%) was found. Peaking month of these AIVs was February 2006, the low pathogenic avian influenza (LPAI) (H5N2) viruses were isolated almost monthly from the LBM. Additionally, multiple subtypes of AIVs were also continuously co-circulating in different months, and H4 and H5 subtypes were most frequently [4%(79/1924) and 2%(29/1924)]. The analysis of phylogenetic trees of HA gene found that those isolated Taiwan’s H5N2 viruses in LBM during Oct 2005-Oct 2006 clustered as an independent group, totally separated from the HPAI H5N1 isolates from Southeast Asia, America and Europe during 1997-2006. Most importantly, our LBM isolated H5N2 viruses were quite different from the 2003 LPAI H5N2 implying that recent LPAI H5N2 viruses have possibly been adapted as Taiwan local strains and circulated in Taiwan LBM for a long time. Among 598 serum samples without auto-agglutination collected from poultry workers (mean+SD of age: 46±11.5 years, males: females = 7:3) in Taiwan and Kinmen during October 2005 to January 2007 with available information and their serum samples without auto-agglutination were tested for their antibodies against [A/Duck/Taiwan/LBM01/2005(H5N2)]. The results showed that the overall seroprevalence rate of the 566 participated poultry-related workers against this LPAI H5N2 virus was 23.5% (133/566). Univariate analysis found that the major risk factors of those workers were age and occupation. The odds ratios (ORs) of poultry-related workers older than 52-year-old and 40~52 year-old were 3.14 [95% confidence interval (C.I) =1.82-5.43, p<0.0001) and 1.79 (95% C.I) =1.03-3.11, p=0.038), respectively compared to those younger than 40 year-old. In occupation, the ranking of the risk to acquire the infection of this H5N2 were swine farmers [OR=21.6, 95% CI.=3.94-118, p<0.0001] followed by LBM workers [OR=4.87, 95% CI, 1.46-16.2, p=0.005]; government officials [OR=4.33, 95% CI.=1.14-16.5, p=0.02], duck farmers [OR=3.94, 95% CI.=1.06-14.6, p=0.03], and chicken farmers [OR=1.66, 95% CI.=0.45-6.11, p=0.44]. Most interesting is workers who were responsible for cleaning (OR=2.50, 95% CI. =0.19-32.20, p=0.47), selling (OR=2.39, 95% CI. =0.27-21.29, p= 0.42), organ processing (OR=2.50, 95% CI. =0.21-29.25, p= 0.46) and slaughtering (OR=1.82, 95% CI. =0.19 -17.19, p=0.60) had higher risk for infection of this H5N2 compared to their family members. No statistically significant was found in the relationship between the infection and other variables such as frequency of wearing personal equipments, having animal farms near home, buying pets, traveling within six month or having ILI symptoms within three months. In conclusion, we found the LBM workers had exposed to LPAI H5 viruses for several months, and positive antibodies against this LPAI H5N2 virus indeed were identified in poultry-related workers. Up to now, Taiwan is a HPAI H5N1-free area. While China and other counties in Southeast Asia have had HPAI H5N2 outbreaks, we should make the most efforts to prevent introduction and subsequent outbreaks of avian influenza in Taiwan. We should continuous the surveillance in the LBM due to three important characters, such as LBM is the avian-human interface, co-circulating multiple subtypes and LPAI H5 viruses presented in Taiwan LBM. The most efficient prevention and control of AI in the future relies on sincere collaborations among government agencies, public and teaching/research institutes. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/24993 |
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Appears in Collections: | 流行病學與預防醫學研究所 |
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