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目的了解广东省南澳岛广州管圆线虫(Angiostronglyus cantonensis)中间宿主福寿螺(Pomacea canaliculata)和终末宿主鼠类的分布密度及感染现状。方法于2015年12月-2016年9月采用分层随机抽样法分别从南澳岛抽取宫前村、金山村、六都村等3个行政村作为调查点。采集福寿螺、捕获鼠类,GPS仪记录各采样点的数据。福寿螺经形态学鉴定后,提取基因组DNA进行PCR检测复核螺种。福寿螺感染情况先用肺检法检测肺囊,再用酶消化法和匀浆法检查螺肉和肺囊。鼠类经形态学初步鉴定鼠种及性别后,再解剖采集肝脏用于PCR检测复核鼠种,剖检心、肺组织检查有无广州管圆线虫成虫感染。采集到的广州管圆线虫经形态学鉴定后,再进行PCR检测鉴定虫种。采用SAS9.3统计学软件对福寿螺、鼠类密度和感染情况进行统计分析。结果共采集福寿螺2 192只,随机选取1 190只用于检测,其中阳性螺72只,阳性率为6.1%。共捕获鼠类110只,包括褐家鼠(Rattus norvegicus)、黄胸鼠(R.flavipectus)、黄毛鼠(R.losea)和臭鼩(Suncus murinus)4个鼠种,其中阳性鼠32只,感染率为29.1%(32/110),褐家鼠感染率为36.5%(31/85),黄胸鼠有1只感染,黄毛鼠和臭鼩均为阴性;福寿螺和鼠类线粒体DNA细胞色素氧化酶Ⅰ亚基(COⅠ)扩增片段长度分别约670、706 bp,广州管圆线虫核糖体DNA内转录间隔区2(ITS2)扩增片段长度约693 bp,与预期大小相符。不同季节福寿螺密度(H=11.603 5,P<0.01)和感染率(χ~2=65.1 441,P<0.01)差异均有统计学意义,不同季节鼠的密度差异也有统计学意义(H=19.268 2,P<0.01);河道环境福寿螺密度最高(8.8只/m~2),但不同孶生环境下福寿螺的密度差异无统计学意义(H=3.909 3,P>0.05)。沟渠环境福寿螺平均感染率最高(7.5%,42/429),且福寿螺和鼠类感染率与离居民区距离密切相关,呈现离居民区越近感染率越高的趋势。体质量大的鼠类平均感染率要高于体质量小的鼠类,不同体质量鼠类感染率差异有统计学意义(χ~2=17.530 4,P<0.01)。结论广州管圆线虫重要中间宿主福寿螺和终末宿主鼠类在南澳岛分布广泛,且均存在不同程度的感染。
Objective To investigate the distribution density and infection status of Pomacea canaliculata and terminal host mice in Nanao Island, Guangdong Province, the middle host of Angiostronglyus cantonensis. Methods From December 2015 to September 2016, stratified random sampling method was used to take three administrative villages such as Gongqian Village, Jinshan Village and Liudu Village respectively from Nan’ao Island for investigation. Collect snails, capture mice, GPS instrument records the data of each sampling point. Flos lonicera morphologically identified, genomic DNA was extracted for PCR detection of snail species. Spirillum infection first detected by pulmonary detection of lung sac, and then digested by enzyme and homogenate to check the snail and lung sac. Rodents were initially identified by the morphology of mice and sex, and then dissected and collected liver for PCR detection of re-examination of rat heart, heart and lung tissue examination with or without infection of adult worm angiostrongyliasis. The collected Cordyceps polygoni multiflori were identified by morphology, and then PCR detection was used to identify the species. SAS9.3 statistical software was used to analyze the density and infection of snails. Results A total of 192 192 snails were collected and 1 190 randomly selected for testing. Among them, 72 were positive, with a positive rate of 6.1%. A total of 110 rodents were captured, including 4 Rattus norvegicus, R. flavipectus, R.losea and Suncus murinus, of which 32 , Infection rate was 29.1% (32/110), infection rate of Rattus norvegicus was 36.5% (31/85), there was only one infection in Rattus flavipectus, but both rodents and stinkbug were negative; The lengths of cytochrome oxidase Ⅰ subunit (COⅠ) amplified fragments were about 670 and 706 bp, respectively. The length of ITS2 amplified fragment of ribosomal DNA of C. elegans was 693 bp, which was consistent with the expected size. There were significant differences in the density (H = 11.603 5, P <0.01) and infection rate (χ ~ 2 = 65.1441, P <0.01) in different seasons, and there were also significant differences in density among different seasons (H = 19.268 2, P <0.01). The highest density of snails (8.8 / m ~ 2) was found in the river environment, but there was no significant difference in density between snails (H = 3.909 3, P> 0.05). The highest average infection rate (7.5%, 42/429) was in ditch environment, and the infection rate of snails and rodents was closely related to the distance from residential areas, showing a trend of higher infection rate. The average infection rate of rats with high body weight was higher than that of mice with low body weight. There was significant difference in the infection rate of different body weight rats (χ ~ 2 = 17.5304, P <0.01). Conclusion The main intermediate host of A. cantonensis, Hirudosia japonica and terminal host mice are widely distributed in Nanao Island and all have different levels of infection.