湘鄂地区猪颚口线虫病调查及三种颚口线虫幼虫的光镜和扫描电镜观察

研究了湘、鄂地区猪刚刺颚口线虫Gnathostoma hispidum流行病学和三种颚口线虫幼虫比较形态学,共检查猪192只,平均感染率47.4％,检查鱼类16种,其中刚刺颚口线虫第3期幼虫旧性8种;两栖类5种,阳性3种,金线蛙Rana plancyi是首次发现的转续宿主,对我国蛙类体内发现的3种颚口线虫第3期幼虫作了详细的光学和扫描电镜形态比较并提出这3种幼虫的主要鉴别特征。     

陶氏颚口线虫流行病学调查及动物感染实验

报道四川省名山和峨边县为陶氏颚口线虫典型流行区，猪的感染率为５．６％和１８．６％；在流行区新发现４种硅和一种蟾蜍为本虫的第二中间宿主。野猪是本病的重要感染源，感染率高达６８．２％。实验证明鼠类和家鸡、鸭为本虫的适宜转续缩主。     

刚刺颚口线虫病流行区的发现及其生物学研究

剖检猪 1 213只,平均感染率 23.6％。鱼类检查 19种,本虫第三期幼虫阳性者 7种。两栖类检查 4种,阳性 2种,其中虎纹蛙 Rana tigrina rugulosa 是转续宿主新纪录,感染率高达 50％。家猪每月定点调查结果表明全年均可受本病侵袭,春夏季感染率高于秋冬季;湖区感染率明显高于非湖区。对终宿主和中间宿主体内寄生的2种易混淆的颚口线虫鉴别特征作了简述。扼要讨论了防治措施。     

厦门地区广州管圆线虫的流行病学调查

调查了人体脑炎病原—广州管圆线虫在厦门地区的存在与散布情况。结果证实褐家鼠和褐马云玛瑙螺分别是该地区本线虫的终末宿主和中间宿主,其自然感染率分别为31.8％和34.1％;感染强度分别是平均13条成虫和24条幼虫。感染期幼虫在玛瑙螺体内以肺组织含虫率最高(72.0％),还讨论了生物和环境因子与本线虫自然感染的关系。     

江苏省洪泽地区动物的棘颚口线虫病流行学调查及病原学研究

江苏洪泽地区是动物颚口线虫病严重流行区。此地的鱼类、两棲类、爬行类和鸟类等动物,自然感染该线虫甚为普遍。病原虫种经动物感染实验,巳证实有二种。家猫是流行区棘颚口线虫病主要疫源动物。对感染途径作了简要讨论并提出防制对策     

温州海区长蛇鲻寄生线虫幼虫的分布模式

作者对温州海区常见30多种经济鱼类作为中间宿主感染寄生虫的情况进行了调查,结果表明15．2％的被检鱼类寄生单殖吸虫,而63．6％的被检鱼类有线虫寄生,文中着重对不同体长组长蛇鲻体内寄生线虫的状况进行研究,随着宿主体长的增长,其感染强度和平均密度有逐渐增加的趋势,宿主体内寄生率及密度占绝对优势的Anisakis simplex幼虫和Contracaecumsp,幼虫在宿主体内的频率分布,表明多数宿主不感染或只感染少量的线虫幼虫,少数宿主感染线虫幼虫数量较大,线虫幼虫在宿主种群的分布格局类型均为聚集分布。     

陶氏颚口线虫生活史的研究

本文报告陶氏??线虫发?史,对发育各期均作??考察和描述。经实验证实,在?门??,充?本虫第一中间宿主的剑水蚤有6种,短角??水蚤Apocyclops royi和台湾温剑水蚤Thermocyclops faihokuensis ??发现的第一中?宿主,??报告将含有早第??幼虫的剑水蚤感染虎纹?Rana tigrina rugulosa获得成功,在26～28℃条件下,?虫卵到第三期幼虫侵入猪体内发育至成虫成熟?卵约?125～130天。     

分棘四棱线虫的生活史研究

本文报道了分棘四棱线虫在中间宿主和终末宿主体内的发育情况。在16—22℃下,虫卵被异壳介虫吞下后数小时,第1期幼虫即孵化出来,进入宿主组织中寄生。第8天后进入第2期,消化道逐渐形成。第13天后进入第3期,尾端的棘刺排成1圈,圈中央为1个棘刺。生殖原基呈团状,雄虫的生殖原基靠近肠前部附近;雌虫的生殖原基在肠的后部靠近直肠。感染雏鸭后,幼虫生殖原基即开始迅速发育。至感染后第3天,幼虫蜕皮进入第4期,雄虫的交合刺与泄殖腔、雌虫的储精囊形成。感染后第7天,幼虫最后一次蜕皮,雌虫进入拉培根窝内寄生,虫体开始显著膨大。感染后13天雌雄虫分别出现精子与虫卵。感染后15天,出现发育成熟的虫卵。     

台湾海峡经济鱼类感染寄生线虫幼虫的调查

自１９９６年４月至１９９８年１月间,对台湾海峡常见８０多种经济鱼类作为中间宿主感染寄生线虫幼虫的情况进行了调查．报道了该海域中常见的８种鱼类寄生线虫幼虫及它们在鱼类中的感染状况．结果表明约５９．２６％的鱼类感染了线虫幼虫．可感染６种线虫幼虫的鱼类有灰海鳗、蓝圆鱼参和大带鱼等;绝大多数鱼类仅感染２～３种．优势种幼虫之一的Ｃｏｎｔｒａｃａｅｃｕｍｓｐ．２约感染５４．３２％的受检鱼类．感染鱼类较多还有Ｃｏｎｔｒａｃａｅｃｕｍｍｕｒａｅｎｅｓｏｘｉ和Ａｎｉｓａｋｉｓｓｉｍｐｌｅｘ幼虫,它们的感染率分别是３２．１０％和２１．１６％．感染强度较大的３种幼虫分别是Ｃｏｎｔｒａｃａｅｃｕｍｓｐ．２、Ａｎｉｓａｋｉｓｓｉｍｐｌｅｘ和Ｒａｐｈｉｄａｓｃａｒｉｓｔｒｉｃｈｉｕｒｉ（ＹｉｎｅｔＺｈａｎｇ,１９８３）,它们的平均感染强度分别为４６．２５、４７．１４和２８．７８条／尾．本海域另一个优势种线虫幼虫是Ｒａｐｈｉｄａｓｃａｒｉｓｔｒｉｃｈｉｕｒｉ（ＹｉｎｅｔＺｈａｎｇ,１９８３）．     

台湾海峡鱼类寄生针晶蛔和对盲囊线虫幼虫的动态

以蓝圆鱼参 Decapterusm aruadsi为宿主,对台湾海峡鱼类寄生线虫幼虫中两个优势种平均感染强度与蓝圆鱼参叉尾长及体重间的关系、线虫幼虫的感染强度、雌雄性比及幼虫性腺发育的月变化动态进行了观察.初步探讨环境温度和宿主生物学特性等与线虫幼虫动态间的关系.     

日本棘隙吸虫生活史及流行学的研究

本文对日本棘隙吸虫Echinochasmus japonicus生活史各期进行了详细的描述补充了未被报告的蚴虫期,使生活史得以完整;调查并感染实验证实在我国纹沼螺是该吸虫第一中间宿主,18种螺、鱼和蝌蚪充当第二中间宿主(其中6种为新的中间宿主);首次报告本省纹绍螺及家禽自然感染情况;同时找出该吸虫病传播的新途径,为防治本病提供了科学依据.     

福建省家鸭光口科吸虫及其病害

本文报告寄生于我省家鸭的光口科Psilostomidae吸虫4属11种,其中2种为国内新记录;发现淡水虾类充当福建光孔吸虫新的第二中间宿主,首次报道杯叶科Cyatho-cotylidae的囊蚴寄生于福建光孔吸虫裂蚴体内;种不同科的吸虫蚴虫寄生于蚴虫属罕见寄生现象;对单睾球孔吸虫和福建光孔吸虫的流行病学、病害和防治作了叙述;试验表明硫双二氯酚是治疗本病的高效、低毒的药物。     

Population biology of infectious diseases: Part II.

In the first part of this two-part article (Nature 280, 361--367), mathematical models of directly transmitted microparasitic infections were developed, taking explicit account of the dynamics of the host population. The discussion is now extended to both microparasites (viruses, bacteria and protozoa) and macroparasites (helminths and arthropods), transmitted either directly or indirectly via one or more intermediate hosts. Consideration is given to the relation between the ecology and evolution of the transmission processes and the overall dynamics, and to the mechanisms that can produce cyclic patterns, or multiple stable states, in the levels of infection in the host population.     

福州市郊分棘四棱线虫病的流行情况与中间宿主

本文报道分棘四棱线虫两种新的中间宿主：介形虫和蚤蝇，确定了介形虫为福州市郊分棘四棱线虫病的主要传播媒介，通过剖检得出，麻鸭、半番鸭的感染率达５３．２％和１１．１％，平均感染强度分别为３８．１只和１０．７只，文中从流行病学的角度探讨了该病的控制方法。     

Population dynamics of Schistosoma mansoni in mice repeatedly exposed to infection

Studies of host resistance to parasite infection are usually based on experimental designs involving a primary infection and subsequent challenge exposure, resistance being recorded as the percentage reduction in parasite establishment in challenged hosts when compared with that in uninfected animals. Few studies have focused on the dynamic nature of helminth establishment and mortality (and their presumed dependency on the rate of current exposure and past experiences of infection) in hosts repeatedly exposed to low levels of infection. Here, we report the results of population studies on the dynamics of resistance to Schistosoma mansoni infection (a helminth parasite) in mice repeatedly exposed to cercarial invasion. Parasite burdens created by different levels and durations of exposure to infection reflect a dynamic interplay between rates of helminth establishment and mortality. Depending on the intensity of exposure, changes in worm load with duration of host infection vary from monotonic growth to a stable average parasite burden to convex curves in which the average load attains a maximum value before decaying in old animals. These trends are similar to observed patterns of S. mansoni infection in human communities.     

The effect of migration on local adaptation in a coevolving host-parasite system

Antagonistic coevolution between hosts and parasites in spatially structured populations can result in local adaptation of parasites; that is, the greater infectivity of local parasites than foreign parasites on local hosts. Such parasite specialization on local hosts has implications for human health and agriculture. By contrast with classic single-species population-genetic models, theory indicates that parasite migration between subpopulations might increase parasite local adaptation, as long as migration does not completely homogenize populations. To test this hypothesis we developed a system-specific mathematical model and then coevolved replicate populations of the bacterium Pseudomonas fluorescens and a parasitic bacteriophage with parasite only, with host only or with no migration. Here we show that patterns of local adaptation have considerable temporal and spatial variation and that, in the absence of migration, parasites tend to be locally maladapted. However, in accord with our model, parasite migration results in parasite local adaptation, but host migration alone has no significant effect.     

Schistosoma mansoni shares a protective oligosaccharide epitope with freshwater and marine snails

The expression of similar antigenic determinants by trematode parasites and their intermediate (invertebrate) or definitive (vertebrate) hosts has been previously reported. Studies of experimental and human infection by the parasite Schistosoma mansoni have revealed the strong immunogenicity of a surface antigen with a relative molecular mass (Mr) 38,000 (38K). Here we provide evidence that the important protective epitope of the 38K molecule is expressed by the uninfected intermediate host of S. mansoni, Biomphalaria glabrata and is synthesized both by the mollusc and by the parasite throughout its life cycle, thus confirming our original hypothesis. Deglycosylation experiments indicate that the protective epitope is an oligosaccharide and in B. glabrata, is associated with a 90K component. Analysis of soluble extracts from different freshwater mollusc species shows that the same protective epitope is found in schistosome as well as in non-schistosome hosts. Moreover, it was also found on the haemocyanin of the keyhole limpet (Megathura crenulata), a carrier protein widely used in immunological studies.