養牛場庫蠓族群監測及嗜牛庫蠓對牛流行熱病毒之病媒能力

Population surveillance of Culicoides spp. (Diptera: Ceratopogonidae) in diary and vector competence of Culicoides oxystoma to bovine ephemeral fever virus

簡伊萱(Yi-Hsuan Chien)

指導教授 ： 張念台

國立屏東科技大學/農學院/植物醫學系所/碩士(2014年)

https://doi.org/10.6346/NPUST.2014.00279

摘要

本文調查臺灣各地區養牛場庫蠓 (Culicoides spp.) 發生種類，並監測其族群消長，探討監測期間之病媒庫蠓數量與氣象因子及牛流行熱疫情發生之關係，並進一步檢測養牛場優勢種嗜牛庫蠓(C. oxystoma) 之病媒能力，藉人工感染方式檢測牛流行熱病毒於病媒庫蠓體內的存活及傳毒情形。庫蠓種類調查自2012年間於花蓮縣、雲林縣、嘉義縣、臺南市、高雄市及屏東縣等地區共14個養牛場設置燈光誘捕器，於下午五點至翌日上午八點進行誘集，結果經鑑定共採得17種庫蠓，其中以屏東滿州地區誘得13種庫蠓最多，而嗜牛庫蠓則為各場之優勢種，其發生比例佔所有場區的62.54%。庫蠓族群消長監測自2012年3月至2014年3月間於雲林縣、嘉義縣、臺南市、高雄市、屏東縣等地進行，共調查5區養牛場，其中以雲林縣斗南鎮每月平均誘捕達2,240.56 ± 2,288.93隻數量最多。根據各場兩年間每月族群監測之結果，除高雄市燕巢區外，其他場區皆以6月至10月間庫蠓發生數量最多，而12月到2月較低。另外以各場區每月平均採集數量，其第一年監測 (2012年3月至2013年2月) 的庫蠓發生數皆比第二年監測 (2013年3月至2014年2月) 者所得為低。各場庫蠓族群數量與氣象因子中的雨量及溫度之相關性較高，尤其屏東鹽埔場區庫蠓數與前一個月的氣象因子呈現高度正相關性 (p<0.001)，隨著溫度及降雨量上升，發生量也會增加。各場區牛流行熱發生的時期皆在 2012年11至2013年1月之間，且除嘉義場區外，其他調查場區均於庫蠓族群達高峰後的1至3個月爆發牛流行熱疫情。另分析養牛場牛流行熱與庫蠓族群發生的結果指出，雖然庫蠓密度高時 (20,000 ~ 40,000隻/月) ，會增加疾病流行的可能性，但當此病媒養牛場密度低 (1,500隻以下/月) 時，亦可能會因牛場內病原的存在，造成牛流行熱疫情的發生。為確定嗜牛庫蠓為爆發疫情之主要物種，本研究以人工感染方式證實嗜牛庫蠓之傳毒能力，其病毒檢出率隨著時間增長而增加，牛流行熱病毒可以在庫蠓體內複製，並於14日後達最高峰，且病毒能在庫蠓體內保毒長達14日。另將庫蠓以胸部注射接種法感染牛行熱病毒，進一步證實嗜牛庫蠓可藉由吸食傳播病原，且於獲毒10日後之病毒檢出率可達100%。由於臺灣位處亞熱帶，全年溫熱潮溼、雨量豐沛的季節相當長，使不同地區病媒庫蠓數量會隨著氣候與環境因子起伏，未來應進行長期監控病媒庫蠓數量之變動，藉以了解養牛場病媒庫蠓發生情況，做為防治及牛隻施打疫苗時機之參考。另外，不同種類庫蠓之病媒能力亦應進行探討，以建立庫蠓媒介牛流行熱之流行病學基礎及病媒種類資料庫，作為防治之參考。

關鍵字

庫蠓 ； 牛流行熱 ； 監測 ； 族群消長

並列摘要

The objectives of this research are to detect the species, survey population dynamics of Culicoides species in Taiwan, and also to test the susceptibility and transmit ability of C. oxystoma to bovine ephemeral fever (BEF) virus. Totally 17 species of Culicoides were collected and identified by light traps which were settled at 14 dairies in Hualien, Yunlin, Chiayi, Tainan, Kaoshiung and Pingtung of Taiwan. The most 13 species of Culicoides were detected in Pingtung county while C. oxystoma was the predominate species (62.54%) in all dairies. Surveillance of Culicoides spp. were conducted in 5 dairies located at central and south Taiwan. Culicoides were Sampled by light traps during the sunset to sunrise every week from March 2012 to March 2014. The most mean number, 2,240.56 ± 2,288.93/month, of Culicoides were caught in Yunlin county. The population peak occurred during June to October, and drop in December through February. The monthly number of Culicoides collected in the 1st year (Mar. 2012 to Feb. 2013) was lower than that in the 2nd year (Mar. 2013 to Feb. 2014). The significant correlation (p<0.001) were found among number of Culicoides and temperature and rainfall in Pingtung county. When temperature and rainfall increased, number of Culicoides collected increased. Basing on the report, the BEF occurred in most of dairies during November 2012 to January 2013. Actually, except Chiayi county, those outbreak of BEF in all other sample sites occurred in 1-3 months after the Culicoides populations reach peak, Although the outbreak of BEF may rise when the density of Culicoides is high (20,000-40,000 / month)，nevertheless BEF can also occur in the period of low density (under 1,500 / month) when the pathogen possibly incubate in the dairies. The C. oxystoma is the dominant species in the dairies of which BEF had broken out. This study, thus, confirm the transmission competence of C. oxystoma by artificially infected BEF virus. The result indicates that inoculation rate increased with the increasing of the time after artificially infected. BEF virus is able to replicated in C. oxystoma, and furthermore, the virus can remain the activity and reach a peak of inoculation rate at the 14th day after infection. Moreover, the intrathoracic inoculation of BEF virus confirmed that C. oxystoma is the vector of this disease. C. oxystoma was proved being able to spread the pathogen by sucking blood, and the infection rate reached to 100% at 10th day after acquiring pathogen. Because subtropical climate in Taiwan, it’s warm and wet year-round, which usually cause the density of Culicoides keeping high in all survey areas. However, the environmental factors are significantly different in varius areas and long-term monitoring is important for each dairies. The surveillance of Culicoides is necessary for understanding the occurrence, time to control of this vector, as well as timing of vaccination in each cattle farm. Also, the establishment of the epidemiology data basing on the infection ability of BEF and various Culicoides species are warrant.

並列關鍵字

Culicoides spp. ； Bovine ephemeral fever ； Surveillance ； Population fluctuation

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