流浪動物體表外寄生蟲感染病媒性病原之流行病學研究

外文標題: 
Epidemiological Study of Vector-borne Pathogens in Ectoparasites from Stray Animals
校院系所: 
中興大學獸醫公共衛生學研究所
指導教授: 
張照勤
出版年份: 
2009年
主題類別: 
摘要: 

巴東體屬菌(Bartonella spp.)與立克次體(Rickettsia spp.)皆為人畜共通病原,其主要藉由多種節肢動物病媒傳播(如:跳蚤、硬蜱、體蝨)。在過去許多的流行病學研究均顯示,寄生於犬貓體表的外寄生蟲可感染這兩類病原,進而導致人類的意外感染。本研究的目的為評估寄生於流浪犬貓體表的跳蚤及硬蜱感染Bartonella及Rickettsia的盛行率,以及對於人類健康的可能威脅。本研究自37隻流浪犬及4隻流浪貓體表共採集451隻貓蚤(Ctenocephalides felis),並且將這些貓蚤分成158個集合檢體(每集合檢體含有一到三隻貓蚤)。此外,本研究之檢體也包括額外從62隻流浪犬體表採集的386隻 Rhipicephalus硬蜱。依照齡期可將這些Rhipicephalus 硬蜱區分為幼蜱(32.6%, 126/386),若蜱(18.9%, 73/386),以及成蜱(48.4%, 187/386),並進一步將幼蜱分成21個集合檢體(每集合檢體內含一到十隻幼蜱)。利用PCR、分子選殖(molecular cloning)及gltA基因部分序列定序以檢測及鑑定檢體感染Bartonella spp.及Rickettsia spp.的情形。實驗結果顯示,44.3%(70/158)的貓蚤集合檢體有Rickettsia的DNA,相較於只有13.9%(22/158)的貓蚤集合檢體Bartonella之PCR檢測為陽性反應(p<0.05)。本研究也發現14.3%(3/21)的幼蜱集合檢體,17.8%(13/73)的若蜱檢體,以及6.4%的成蜱檢體可檢測到Bartonella的DNA。在幼蜱集合檢體及若蜱檢體並未發現含有Rickettsia的DNA,然而在 6.9%(13/187)的成蜱檢體有感染Rickettsia的情形。依基因序列的分析結果顯示,在受測的外寄生蟲檢體中發現不同種類的 Bartonella及Rickettsia。於貓蚤檢體有檢測到B. henselae(36.4%, 8/22)、B. clarridegiae(4.5%, 1/22),以及一個和B. sp. SL-1相似的菌株(59.1%, 13/22)。同時也發現所有Rickettsia之PCR陽性的貓蚤檢體皆為感染R. felis。在Rhipicephalus的幼蜱集合檢體中檢測到B. henselae (66.7%, 2/3)及B. rattimassiliensis(33.3%, 1/3)。而在Rhipicephalus若蜱檢體則可發現不同菌種的Bartonella,包括有B. henselae(46.2%, 6/13)、B. grahamii(23.1%, 3/13)、B. phoceensis(15.4%, 2/13)、B. elizabethae(7.7%, 1/13),及B. rattimassiliensis (7.7%, 1/13)。於Rhipicephalus的成蜱檢體則檢測到B. henselae (58.3%, 7/12)、 B. elizabethae (16.7%, 2/12)、B. phoceensis (8.3%, 1/12),以及一個和B. sp. SL-1相似的菌株(33.3%, 4/12);進一步檢測出在兩個成蜱檢體出現兩個不同Bartonella菌種混合感染的情形。而所有Rickettsia之PCR檢測陽性成蜱檢體皆為感染R. rhipicephali。本研究結果顯示自臺灣流浪動物所收集的外寄生蟲能夠感染(或攜帶)許多人畜共通病原,包括B. henselae、B. clarridegiae、B. elizabthae、B. grahamii及R. felis等。為了避免這些病原的散播或是意外造成人類感染的情形,定期清除寵物或是流浪動物的外寄生蟲是相當重要的。

外文摘要: 

Bartonella spp. and Rickettsia spp. are zoonotic pathogens. They are mainly transmitted by various arthropod vectors, such as fleas, ticks, and lice. Previous epidemiological studies indicated that ectoparasites infested on dogs or cats may be infected by these pathogens, and transmit them to human beings accidentally. The purpose of this study was to evaluate prevalence of Bartonella and Rickettsia infections among fleas and ticks from stray dogs and cats for human public health. A total of 451 cat fleas (Ctenocephalides felis) from 37 dogs and 4 cats were collected, and then separated into 158 pools (1-3 fleas per pool). Besides, 386 Rhipicephalus spp. ticks collected from another 62 stray dogs were included in this study. With regard to the life stages, the collected ticks of Rhipicephalus spp. were including larvae (32.6%, 126/386), nymphs (18.9%, 73/386), and adults (48.4%, 187/386). Different from nymphal and adult ticks that were analyzed individually, larvae of Rhipicephalus spp. were separated into 21 pools (1-10 larva per pool for detection). Molecular cloning and partial sequencing of the gltA gene after PCR were applied for Bartonella spp. and Rickettsia spp. identification. The results showed that 44.3% (70/158) of the cat flea pools were harboring Rickettsia DNA, comparing to only 13.9% (22/158) of the cat flea pools that were PCR positive for Bartonella (p<0.05). It was also found that 14.3% (3/21) of larval pools, 17.8% (13/73) of nymphal ticks, and 6.4% (12/187) of adult ticks, were PCR-positive for Bartonella, respectively. Although 6.9% (13/187) of adult ticks were infected with Rickettsia, neither larval pools nor nymphal ticks were found to contain Rickettsia DNA. According to the results of sequence analyses, different Bartonella spp. and Rickettsia spp. were identified in the ectoparasites tested. Accordingly, B. henselae (36.4%, 8/22), B. clarridegiae (4.5%, 1/22), and a strain closely related to B. sp. SL-1 (59.1%, 13/22) were detected in cat flea pools. It was also found that all Rickettsia PCR-positive cat flea pools were infected with R. felis. In larval pools of Rhipicephalus spp., B. henselae (66.7%, 2/3) and B. rattimassiliensis (33.3%, 1/3) were detected. Various Bartonella spp. were found in nymphs of Rhipicephalus spp., including B. henselae (46.2%, 6/13), B. grahamii (23.1%, 3/13), B. phoceensis (15.4%, 2/13), B. elizabethae (7.7%, 1/13), and B. rattimassiliensis (7.7%, 1/13). In the adults of Rhipicephalus spp., B. henselae (58.3%, 7/12), B. elizabethae (16.7%, 2/12), B. phoceensis (8.3%, 1/12), and a strain closely related to B. sp. SL-1 (33.3%, 4/12) were detected. This study further identified that two adult ticks were co-infected with two species of Bartonella. All Rickettsia PCR- positive adult ticks were infected with R. rhipicephali. The results of this study demonstrated that ectoparasites collected from stray animals in Taiwan could be infected or carry many zoonotic pathogens, including B. henselae, B. clarridegiae, B. elizabethae, B. grahamii, and R. felis. Therefore, control of ectoparasites infested on pets or stray animals regularly will be very deterministic to prevent humans from accidental Bartonella and Rickettsia infections.