小白鼠腹腔接种微丝蚴建立牛腹腔丝虫动物模型

建立了可代替病源牛的小鼠动物模型。给昆明小鼠腹腔接种分离自成牛腹腔丝虫子宫内的微丝蚴混悬液,所有试验鼠均出现了高密度的微丝蚴血症并持续一个月以上。叮咬模型小鼠的东乡伊蚊对牛腹腔丝虫易感。感染蚴经10—14天发育成熟。应用此新技术可为脑脊髓丝虫病研究提供大量感染蚴并有助于其它种动物丝虫的生活史的调查研究。     

唇乳突丝虫感染蚴接种非固有宿主动物致发脑脊髓丝虫病研究

用东乡伊蚊叮吮含有唇乳突丝虫微丝蚴的模型动物——小鼠血液,待微丝蚴在蚊体内发育至感染期时,分离出感染坳,皮下多点接种43只昆明小鼠(每只15～200条)、1只山羊及2只绵羊(每只200～300条)和4匹驹(每匹750～1 250条);将指状丝虫接种到20只昆明鼠体内,比较两种虫体的致病性。结果:唇乳突丝虫感染鼠有16只经1～8 d潜伏期发病,呈现瘫痪、昏迷症状后死亡.实验羊和驹经5～21d潜伏期后均呈不同程度的运动和神经症状,于接种虫体后40～140 d扑杀.经病理学观察,3种动物脑脊髓均呈现虫伤性液化坏死灶及非化脓性脑脊髓炎变化,在其中枢神经系统组织切片中发现丝虫虫体断面或钙化碎片,从而证明唇乳突丝虫可人工感染昆明小鼠、羊、驹发生脑脊髓丝虫病,进而提出该虫可以成为马、羊脑脊髓丝虫病的病原之一。指状丝虫感染鼠死亡率高于唇乳突丝虫感染鼠(P<0.01),初步认为唇乳突丝虫致病性较指状丝虫弱。     

牛腹腔丝虫感染蚴接种犊牛试验

牛腹腔丝虫感染蚴皮下接种非固有宿主马和羊,均发生脑脊髓丝虫病;接种沙鼠、小白鼠、大白鼠、豚鼠等实验小动物,亦均发生类似于马、羊脑脊髓丝虫病的临床症状及病理学变化。日本学者河野猪二郎曾报道在自然界中牛有脑脊髓丝虫病的病例。在马脑脊髓丝虫病发病机理研究中,我们以牛腹腔丝虫感染蚴接种固有宿主犊牛试验,企图通过人工造病,建立牛腹腔丝虫虫源模型。报告如下。     

中西医结合防治犬恶丝虫病

<正>犬恶丝虫病又称恶心丝虫病、犬血丝虫病,是由双瓣科恶丝虫属的犬丝虫寄生于犬的右心室和肺动脉所引起的一种丝虫病。临床主要为血液循环障碍、呼吸困难、贫血、皮肤有结节等症状。猫、狐、狼、猩猩及人体也可感染。1犬恶丝虫生活史犬恶丝虫是一种微白色细长的线虫。犬恶丝虫需要蚊虫作为中间宿主,其幼虫微丝蚴,也可在猫蚤与犬蚤体内发育。成熟雌虫产生微丝蚴,后者进入宿主的血液循环系统。蚊虫吸血时,微丝蚴随血液进入蚊体内,2周内发育为     

牛腹腔丝虫微丝蚴人工感染蚊体研究

脑脊髓丝虫病在亚洲是危害马及山羊最严重的寄生虫病之一。已查明该病由牛腹腔丝虫的童虫所引起,中间宿主是按蚊;因而给按蚊人工接种病原体微丝蚴是研究本病的必要环节。以往国内外做此接种试验必须先检查牛血中含牛腹腔丝虫微丝蚴的密度,选择达到30条/60mm~3以上的牛供按蚊直接叮咬。但要找到血中微丝蚴含此高密度牛只往往要检查数十头甚至数百头;必须捆绑每一头受检牛,费时费力,经研究现可直接从牛腹腔丝虫子宫内取出微丝蚴感染蚊体。这样既不需捆牛,也不要特殊设备,蚊体吸吮血     

指状腹腔丝虫微丝蚴在中华按蚊体内发育过程中的形态学观察

<正> 指状腹腔丝虫的幼虫是马、羊脑脊髓丝虫病的主要病原,中华按蚊是其主要传播媒介。我们在对福建省马脑脊髓丝虫病病原终宿主及其传播媒介调查研究的基础上,1978年对指状腹腔丝虫微丝蚴及其在中华按蚊体内发育过程中的形态进行了观察,以期通过观察获得指状腹腔丝虫微丝蚴及其在中华按蚊体内发     

牛腹腔丝虫的调查

有关吉林、黑龙江、内蒙古三省的牛腹腔丝虫的种类及分布状况所知甚少。牛腹腔指状丝虫可经蚊虫传播引起羊、马脑脊髓丝虫病,唇乳突丝虫也可经人工感染使动物发生脑脊髓丝虫病。因此了解牛腹腔丝虫的     

江口县山羊脑脊髓丝虫病流行病学调查与防治措施

脑脊髓丝虫病是由寄生于牛腹腔的指形丝状线虫和唇乳突丝状线虫的晚期幼虫(童虫)引起的寄生虫病,羊、马多发[1],蚊是其中间宿主。指形丝状线虫或唇乳突丝状线虫所产生的幼虫(微丝蚴)随血液循环到达末梢血管,当蚊虫叮咬牛只后,微丝蚴即进入蚊体内,经两次平均14 d蜕化发育为感染期幼虫[2],再于蚊叮咬羊时传给羊,侵入羊脑脊髓腔内发育,破坏中枢神经组织。临床症状主要表现为腰髓所支配的后躯运动神经障碍,痿弱和共济失调,故通常称作“腰痿”或“腰麻痹”[3]。笔者对近年来山羊脑脊髓丝虫病在江口县的流行情况和防治措施做一总结,为今后山羊生产提供技术指导。     

指状腹腔丝虫(Setaria digitata)微丝蚴形态学观察

指状腹腔丝虫(Setaria digitata Linstow,1906)是牛体最常见的一种寄生丝虫,成虫寄生于腹腔,其微丝蚴出现在牛的血液循环中。该虫的Ⅲ期蚴能引起非固有宿主中枢神经系统的疾病。据文献记载,它属于亚洲型。我国各地牛体指状腹腔丝虫(Setaria digitata)吴淑卿等作了详细描述。有关指状腹腔丝虫微丝蚴形态研究,至今国内外报道较少。现将牛指状腹腔丝虫微丝蚴的形态观察初步描述如下:     

牛腹腔丝虫感染蚴接种犊牛试验

牛腹腔丝虫感染蚴皮下接种非固有宿主马和羊,均发生脑脊髓丝虫病,接种沙鼠、小白鼠、大白鼠、豚鼠等实验小动物,亦均发生类似于马、羊脑脊髓丝虫病的临床症状及病理学变化。     

Demonstration of vector competence of Culex quinquefasciatus (Diptera: Culicidae) for Setaria digitata

In Taiwan, Setaria digitata infection causes a lumber paralysis in increasing number of cattle. Culex quinquefasciatus is one of the predominant mosquitoes, and it has been suspected that C. quinquefasciatus acts as a vector to Setaria nematodes prevalence but this was not confirmed. C. quinquefasciatus, Aedes albopictus and A. aegypti of various strains were investigated using an artificial infection system to evaluate their vector competence. After blood feeding at day 14, the number of larvae (stage III) per infected mosquito in A. aegypti (Liverpool strain), A. aegypti (Kaohsiung strain), A. aegypti (Tungan strain), C. quinquefasciatus (Taichung strain) and A. albopictus (Taichung strain) was 1.3 +/- 0.1, 1.3 +/- 0.1, 1.4 +/- 0.1, 1.0 +/- 0.0 and 0 +/- 0.0 (mean +/- S.E.M), respectively. The vector efficiency index of A. aegypti (Liverpool) was the highest among mosquitoes whereas A. albopictus showed a complete refractoriness to the infection. In conclusion, C. quinquefasciatus demonstrates its potential competence for serving as a transmission vector of S. digitata. This mosquito might therefore be responsible, at least in part, for the prevalence of cattle lumbar paralysis in Taiwan. This is the first report of C. quinquefasciatu demonstrating its vector competence for S. digitata.     

The incrimination of Aedes (stegomyia) aegypti as the vector of Dirofilaria repens in Nigeria

Six local species of culicides were identified as the common mosquitoes in Zaria, out of 15 species captured using various adult and larval collection methods. These common culicides are Culex pipiens fatigans, Anopheles gambiae grp., Mansonia africana, Culex pipiens pipiens, Aedes (stegomyia) aegypti and Aedes vittatus. They were each fed directly on a local dog naturally infected with Dirofilaria repens to evaluate their refractoriness/susceptibility to dirofilarial infection. In a number of donor-feeding trials, 39. 4% Culex pipiens fatigans; 58.9% An gambiae grp.; 60.5% Mansonia africana; 1.8% of Culex pipiens pipiens; 23.4% Ae aegypti and 3.3% of Ae vittatus successfully fed on the microfilaraemic host. Only Aedes aegypti was susceptible to the infection as all 40 (100%) Ae aegypti reaching 10-14 day post-blood meal had infective (L(3)) larvae of D. repens. The remaining five species were refractory. The microfilariae in the five non-susceptible mosquitoes were always found trapped in the blood meal in the insects midgut (stomach). These trapped microfilaria were dead by the 2nd day in the insect's midgut. However, in the susceptible Ae aegypti, the microfilariae were set free from the blood meal in the midgut and within 24h migrated to the malpighian tubules (MT) of the mosquitoes. All Ae aegypti dissected 5-7 day post-infective blood meal showed the typical quiescent sausage stage (L(2)) larvae in the malpighian tubules. At day-10 post-blood meal, relatively active infective (L(3)) larvae of D. repens were found in the MT; and by day 12-14, highly motile infective larvae had reached the insect's head and proboscis, with infective larvae occasionally oozing out during dissection through the tip of the proboscis. The rate of development of D. repens to infective larvae was faster in mosquitoes infected in July when the environmental temperature was 24.5 degrees C than those infected in November when the temperature was 22.5 degrees C. The latter were delayed for 4 days. The breeding sources of Ae aegypti, the local vector implicated were also identified. As no particular vector of this zoonotic filaria has been identified previously in Nigeria, these findings could make any control programme more focussed and easier.     

A duplex real-time polymerase chain reaction assay for the detection of and differentiation between Dirofilaria immitis and Dirofilaria repens in dogs and mosquitoes

This study describes a duplex real-time polymerase chain reaction (PCR) assay for the detection and differentiation between Dirofilaria immitis and Dirofilaria repens in dog blood and mosquitoes. Regions of a cytochrome oxidase 1 (cox1) mitochondrial DNA fragment and the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA were amplified from microfilariae and adult worm samples, using a sensitive SsoFast? EvaGreen(?) based real-time PCR method coupled with melting-curve analysis. The limit of the real-time PCR in detecting microfilaria and adult worm DNA was also tested both in dog blood and in artificially infected microfilarial. Two peaks at different melting temperatures (T(m)) for D. immitis (mean ± SD=75.7 ± 0.3°C) and D. repens (mean ± SD=70 ± 0.7°C), respectively, were obtained for microfilarial and adult positive controls of both species when examined separately and together. The real-time PCR protocol was also efficient in detecting microfilarial and adult DNA of both species when tested in samples spiked with DNA from Aedes albopictus, in Aedes aegypti experimentally infected by D. repens and in Culex pipiens naturally infected by D. repens and D. immitis. The high sensitivity of real-time PCR confirmed its reliability in detecting small amounts of genomic DNA either in dog blood or mosquitoes (2.5 pg/μl and 3 × 10(-1)pg/μl for D. immitis and D. repens, respectively). This assay is proposed as a tool for the epidemiological surveillance of the two most important Dirofilaria species in areas where they are endemic and sympatric.     

Cerebrospinal setariosis with Setaria marshalli and Setaria digitata infection in cattle

Setaria digitata and S. marshalli larvae were observed in the cerebrospinal cavity of 2 paralyzed cattle in Taiwan. The 2 affected cattle showed quadriplegia and lumbar paralysis, respectively. At necropsy, which was performed 7 days after the 7-month-old cattle became quadriplegic, three and nineteen S. marshalli larvae as well as two female adult worms were found in the cranial cavity, spinal cavity and peritoneal cavity of the cattle, respectively. Necropsy on the other 8-month-old cattle was also performed 3 days after it showed lumbar paralysis, and ten S. digitata larvae were found in the spinal cavity. In both cattle, many mononuclear inflammatory cells mixed with a few eosinophils were seen accumulated in the connective tissue around the root of the spinal nerves. Infiltration of eosinophils and mononuclear inflammatory cells into the epidura and arachnoidea of the brain were also observed. The major inflammatory cell was lymphocytes, but neutrophils and eosinophils were also present. The number of cells in the cerebrospinal fluid collected initially from the two affected cattle were 105/0.01 ml and 143/ 0.01 ml, respectively. This is the first report of cerebrospinal setariosis in cattle associated with S. marshalli.     

Comparison of microfilaria concentration method for Setaria digitata infection in cattle and for Dirofilaria immitis infection in dogs

Several peripheral blood microfilaria concentration methods that use Acetone (Acetone test), 2% formalin (modified Knott method), 5% Tween 20 solution, distilled water, 1% or 0.1% SDS were compared for their efficacy in detecting Setaria digitata microfilaria in cattle. The Acetone test was found to be more efficacious than the modified Knott method or the 5% Tween 20 solution test for detecting the S. digitata microfilaria in bovine blood. However, besides the Acetone test, the modified Knott method was also found to be suitable for Dirofilaria immitis microfilaria detection in dogs. SDS and distilled water were found not to be effective as hemolytic agent for the disruption of the red blood cell of both the cattle and dogs. Thus, the Acetone test is recommended for the primary screening of microfilaremia of S. digitata in cattle.     

Molecular characterization and phylogenetic analysis of Setaria digitata of Sri Lanka based on CO1 and 12S rDNA genes

The aim of the present research is to determine the phylogenetic position of Setaria digitata of Sri Lanka in the evolutionary tree of filarial worms. DNA sequences of portions of the mitochondrial genes cytochrome c oxidase subunit 1 (CO1) and small subunit ribosomal RNA (12S rDNA) were analysed. Intra-specific variation was observed in CO1 but not in 12S rDNA. Phylogenetic trees inferred from these two genes resembled one another in recognizing monophyly of Setaria. S. digitata and Setaria labiatopapillosa appear to be sister species.     

Competence of Aedes albopictus and Culex quinquefasciatus as vector of Dirofilaria immitis after blood meal with different microfilarial density

Aedes albopictus and Culex quinquefasciatus were fed canine blood with different microfilarial density of Dirofilaria immitis ranging from 2500 to 25,000 mff/ml. Larval development in these two mosquito species did not differ significantly. Although C. quinquefasciatus ingested more microfilariae, the number of larvae which developed in A. albopictus was invariably greater than in C. quinquefasciatus. Mortality of the engorged A. albopictus was significantly greater than that of C. quinquefasciatus, and higher microfilarial density raised the mortality in both species. The vector efficiency index of A. albopictus was greater than C. quinquefasciatus at all microfilarial densities, but its survival time was much reduced. Thus, dogs with low microfilarial density are implicated as the main source for the transmission of D. immitis from dogs to mosquitoes.     

Growth of bluetongue and epizootic hemorrhagic disease of deer viruses in poikilothermic cell systems

Continuous cell lines from the ticks Dermacentor variabilis, D. parumapertus, D. nitens, Rhipicephalus sanguineus and R. appendiculatus, the mosquitoes Aedes albopictus and Culex quinquefasciatus and the African toad Xenopus laevis were tested for their ability to replicate bluetongue (BT) and epizootic hemorrhagic disease of deer (EHD) viruses, and for their sensitivity as potential isolation systems. BT serotype 17 grew to peak titers of 10(4.5)-10(7.5) TCID50 ml-1 in all except one of the tick cell lines, EHD 2 virus attained titers similar to that of BT 17 in the mosquito and toads cells, but failed to replicate in tick cells. Only Aedes albopictus and Xenopus laevis cells were as sensitive to infection with low-passage BT 11 and EHD 2 viruses as control cultures of Vero and BHK cells. At 27 degrees C, persistent infection of Xenopus laevis cells occurred, producing low yields of BT 17 and EHD 2. When shifted to 32 degrees C, these cultures expressed virus in exponential increments. No cytopathic effect (CPE) was seen in any of the tick-virus systems, but infected mosquito and toad cells detached from the monolayer within 3-6 days after inoculation with either virus. In the toad cells, this CPE was presaged by the development of plaques within 48 h after infection. Potential applications of poikilotherm systems in orbivirus research are discussed.     

不同发芽率纳罗克非洲狗尾草建植第2年草地生产特性研究

于2013年对不同发芽率(1%、2%、5%、10%、15%)条件下建植第2年的纳罗克非洲狗尾草草地进行了干物质产量、分蘖数、株高等生产指标的测定。结果表明,由于纳罗克非洲狗尾草强大的分蘖补偿能力,不同发芽率纳罗克非洲狗尾草在建植第2年草地的生产特性差异不显著。