連江縣及金門縣小型動物體外病媒與潛在病原體關係之研究

Abstract

連江縣及金門縣緊鄰中國大陸東南沿海， 2001年重新開始與馬尾港及廈門港通航，鼠形動物可能藉由頻繁的船隻往返而入侵金馬地區，間接危害農作物及倉儲糧食，同時也會傳播漢他病毒或藉由體外病媒傳播地方性斑疹傷寒等疾病。本論文進行金門縣及連江縣鼠形動物、體外病媒與病原體之間的研究。 於2001-2006年，調查連江縣及金門縣鼠形動物種類組成及族群季節變化。於連江縣4個採集點共佈放13419籠夜，共捕捉6種鼠形動物651隻，分別為溝鼠 (Rattus norvegicus)、屋頂鼠 (Rattus rattus)、小黃腹鼠 (Rattus losea)、家鼷鼠 (Mus musculus)、田鼷鼠 (Mus caroli)及臭鼩 (Suncus murinus)651隻，總捕捉率為4.8%，以臭鼩為優勢種。金門縣於7個採集點共佈放24928籠夜，共捕捉7種鼠形動物2355隻，分別為溝鼠、屋頂鼠、小黃腹鼠、家鼷鼠、田鼷鼠、赤腹松鼠 (Callosciurus erythraeus)及臭鼩，總捕捉率為9.4%，以小黃腹鼠優勢種。兩地捕捉率均以夏季為最高，冬季降至最低。調查期間兩地尚未發現外來鼠種。 於連江縣之鼠形動物體外採集3種蚤類 (Xenopsylla cheopis, Leptopsylla segnis，Nosopsylla Sp.)，而金門縣採集到1屬蚤類 (Nosopsylla Sp.)，蚤種指數 (flea index)分別為及0.24及0.08；兩地皆以屋頂鼠及小黃腹鼠體外所攜帶之蚤類為最多；兩地同時發現鼠形動物採集之蝨類、蜱類、蟎類、恙蟎寄生，其體外寄生蟲對於宿主性別無顯著性偏好。 利用間接螢光免疫法檢測 (indirect immunofluorescent antibody assay, IFA)鼠形動物感染立克次體 (Rickettsia typhi, Rickettsia rickettsii, Rickettsia conorii)之盛行率。連江縣及金門縣其鼠形動物血清含R. typhi之抗體之盛行率分別為3.0% (2/67)及2.7% (5/183)；發現兩地採集之印度鼠蚤數量少，鼠形動物血清含R. typhi抗體陽性率低，蚤總指數與陽性率無顯著性關係，由此可推測連江縣及金門縣之居民感染地方性斑疹傷寒之潛在風險低。 連江縣67隻鼠形動物之R. rickettsii及R. conorii血清盛行率分別為50.7%及37.3%，其中19隻鼠形動物血清同時含兩種抗體。金門縣183隻鼠形動物之R. rickettsii及R. conorii血清盛行率分別為72.7% 及59.0%，其中103隻血清同時含兩種抗體。血清陽性率之鼠形動物體重顯著高於陰性率之鼠形動物 (p<0.05)，但抗體是否為陽性與鼠形動物之性別無顯著性相關。可能原因為體型越大即年齡越大，活動範圍大，與其他動物接觸機率變大，感染體外病媒機率越變多，同時感染立克次體機率也會變多。 於連江縣及金門縣採集鼠形動物並分析其漢他病毒盛行率及病毒型，分別為3.9% (7/178)及3.8% (24/640)，兩者盛行率沒有顯著性差異，病毒型皆為Seoul型 (SEOV)，與台灣流行之漢他病毒型一樣，但與中國大陸常發生之病毒型不同 (Hannta, HTN)。連江縣之復興村 (5.8%)及馬祖酒廠 (10.3%)之盛行率顯著高於其他2個採集點，同樣金門縣料羅港 (主要港口)之漢他病毒盛行率(17.9%)顯著高於其他6個採集點，同時發現距離港口愈遠，陽性率顯著性越低 (p<0.01)，由此可以證明港口為傳播漢他病毒之媒介點。 統計2001-2005年兩地鼠形動物捕捉率與氣象因子 [平均溫度 (℃)，平均相對濕度 (%)及平均降雨量(mm)]，發現5年短時間的資料無法顯着性得知氣候變遷與鼠形動物捕捉率之關係，仍需長時間的監測及調查，才能監控鼠形動物種類的入侵，同時瞭解氣候變化對於當地動物的變化，也必須掌握體外寄生蟲之消長及血清含各疾病抗體發生率之改變，以防止相關疾病之大發生。

The Lienchiang County and the Kinmen County are offshore islands of ROC that are very close to the Mainland China. Since sea-borne transportation among these islands and the mainland was resumed sailing since 2001. Murine-like animals of these isles and Mainland China would possibly spread around among mutual seaports of both sides. It would consequently cause additional damage to crops and animals, as well as propagating murine-borne diseases such as hantavirus, rickettsial diseases etc. This study attempted to know the relationship among murine-like animals, vector and pathogens in Lienchiang and Kinmen Counties. Live-trapping methods was used in this study from 2001-2006. Four trapping stations were set in the Lienchiang County. Six murine-like animals; Rattus norvegicus, Rattus rattus, Rattus losea, Mus musculus, Mus caroli and Suncus murinus, were caught in these stations. Totally, 651 murine-like animals were trapped in 13,419 trap-nights. The trapping rate was 4.8% (651/13,419). Seven trapping stations were set in Kinmen County. Seven murine-like animals; R. norvegicus, R. rattus, R. losea, M. musculus, M. caroli, Callosciurus erythraeus and S. murinus, were caught in these stations. And, 2,355 murine-like animals were trapped at 7 trapping stations in 24,928 trap-nights. The trapping rate was 9.4% (2,355/24,928). Invasion of original murine-like animal species have not been found yet during the period of survey in this study. In Lienchiang County, we collected 44 fleas (8 Xenopsylla cheopis, 24 Leptopsylla segnis and 12 Nosopsylla Sp.) from 186 murine-like animals. The flea index was estimated 0.24. One hundred and ten fleas (Nosopsylla Sp.) from 664 animals were found in Kinmen County. The flea index was estimated 0.17. Although, the highest flea indexes were collected from R. rattus and R. losea in both county. The lice, ticks, mites, and chiggers were collected from the murine-like animals in Lienchiang and Kinmen they didn’t relevant the sex of host significantly. We used indirect immunofluorescent antibody assay (IFA) to detect antibody of rickettsia (Rickettsia typhi, Rickettsia rickettsii, and Rickettsia conorii). The seroprevalences of R. typhi against in murine-like animals were 3.0% (2/67) in the Lienchiang County and 2.7% (5/183) in the Kinmen County, respectively. According to the results mentioned above, few of X. cheopis was found in murine-like animals, low seroprevalence of R. typhi was found in the animals. There was no significant difference between flea index and seroprevalence in all trapping stations. We suggest that prevalence of epidemic of R. typhi in the Lienchiang County and the Kinmen County will be low. The seroprevalence of antibodies against R. rickettsii and R. conorii were 50.7% and 37.3% from 67 murine-like animals in the Lienchiang County, respectively. Nineteen out of sixty seven murine-like animals had positive reactions to both of R. rickettsii and R. conrii. The seroprevalence of antibodies against R. rickettsii and R. conorii was 72.7% and 59.0% from 183 animals in the Kinmen County, respectively. One hundred and three out of one hundred and eighty three animals had positive reactions to both of R. rickettsii and R. conrii. Seroprevalence of murine-like anumals with heavier body weight was significantly different from that of murine-like animals with lighter body weight (p<0.05). Sexes of murine-like animals made no significant difference between infested and non-infested animals. It suggested that the higher antibody (R. rickettsii and R. conrii) prevalence in large size of animals that may be due to territoriality, aggression toward others and more chance will be infected by tick. There was no significant difference in the seroprevalence between the mruine-like animals that collected from two counties (Kinmen 3.8% vs. Lienchiang 3.9%). Besides, hantavirus strain found in both counties was a mild infectious strain: the Seoul (SEOV) strain found in Taiwan, rather then an intensive strain: Hantaan (HTN), found in Mainland China. The positive rate of hantavirus found in trapped murine-like animals (17.9%) in Liaolo, a major seaport, of the Kinmen County, was significantly higher than the these in other trapping stations. The rates of hantavirus found in trapped murine-like animals in Matsu Distillery (10.3%) and Fushing (5.8%) of the Lienchiang County were significantly higher than the those of other stations. Moreover, a significant inverse correlation was found between the seropositive rate and the distance of murine-like animals trapping stations to the seaport (p<0.01). These findings suggested the role of seaport as a source of hantavirus. According to this study that there was no significant difference between trapping rates and climatic factors [temperature (℃), relative humidity (%) and precipitation (mm)]. So not only we need more time to monitor the invasion of original murine-like animal species but also we have much data to analysis the relationship between trapping rate and climatic changes to avoid more public health problems.