動物園內反芻獸的惡性卡他熱病毒感染調查

Abstract

惡性卡他熱 （ Malignant Catarrhal Fever; MCF ）是一種系統性、致命的病毒性傳染病，主要發生於牛及多種馴養及野生的偶蹄類動物。造成惡性卡他熱感染的病源是皰疹病毒屬下的多種病毒，包含α皰疹病毒第一型 (AHV-1)、α皰疹病毒第二型 (AHV-2 )、綿羊皰疹病毒第二型 (OHV-2)、山羊皰疹病毒第二型 (CpHV-2)及MCFV-WTD。 在2008年10月到12月間，台灣地區的野生動物園曾經發生圈養的台灣水鹿突發性大量死亡，組織切片下發現淋巴結大區域的出血壞死、腸道黏膜出血壞死及系統性多器官血管壞死和血管炎，經病理學診斷懷疑為惡性卡他熱。該野生動物園內的所有動物是採集體混養的飼養方式，為了確定感染各種不同的反芻動物的惡性卡他熱病原種類，自2008年七月開始收集動物園內反芻動的物器官生體，和血液樣本，以巢氏聚合酶鍊鎖反應檢測惡性卡他熱病毒，並綜合屍體解剖的病理結果，分析感染不同種反芻動物的惡性卡他熱病毒及不同種反芻動物的惡性卡他熱潛伏感染情形。結果顯示，造成此野生動物園內惡性卡他熱集體感染的病原為綿羊皰疹病毒第二型，其在園內多種反芻動物上都呈現陽性顯性感染，但在園內的綿羊及山羊多為不顯性感染，此病毒在美洲野牛發病多為急性型惡性卡熱，動物於發病後2到3天後死亡。已將感染發病的動物做單獨隔離，並將園區內容易感染發病的反芻獸與病毒的保毒宿主綿羊和山羊做區隔，避免感染情形繼續擴大。

Malignant catarrhal fever (MCF) is a fatal, systemic disease of cattle and other domestic and wild cloven-hoofed animals. Malignant catarrhal fever is caused by several viruses in the genus Rhadinovirus of the family Herpesviridae (subfamily Gammaherpesvirinae), including Alcelaphine herpesvirus 1 (AHV-1), Alcelaphine herpesvirus 2 (AHV-2), Ovine herpesvirus 2 (OHV-2), and Caprine herpesvirus 2 (CpHV-2) and a virus of unknown origin, currently called MCFV-WTD. In October-December 2008, in a safari park in Taiwan, a large number of domestic Formosan Sambar suddenly died. According to pathological finding, there were multifocal lymph node necrotizing and hemorrhage, intestinal mucosa necrotizing and hemorrhage, vascular necrotizing and vasculitis in multiple organs, and were suspected MCF infection. All herbivores housed together in free safari or exhibits. Since 2008, in order to confirm which pathogen caused MCF infection in different kinds of ruminants, we have collected fresh necropsy samples and blood samples from ruminants in the zoo. Then we used nest-PCR for detection and differentiation of MCF viruses from these samples. The results showed the pathogen which caused MCF infection is ovine herpesvirus type 2 (OHV-2) and a lot of ruminants in the zoo were showed positive. Sheep and goat have inapparent infection with OHV-2, American bison showed acute infection with OHV-2. The American bison infected with OHV-2 usually died within two to three days. In order to control infection of OHV-2, isolating animals with clinical signs and separating susceptible animals from sheep, goats or other suspected reservoir hosts in the zoo is important.