人源隐孢子虫小白鼠感染模型的建立

为评价2种常用免疫抑制方法对小白鼠排人源隐孢子虫卵囊规律的影响,将19日龄小白鼠随机分成2组,第1组通过饮水给予地塞米松,第2组采用导胃管灌服地塞米松。第7 d,2组小白鼠灌胃接种人源隐孢子虫,每只小白鼠感染量为1.5×106个卵囊。两组均在感染当天就有卵囊排出,感染后第6 d粪便卵囊计数明显增加,随之出现3个高峰期,此后逐渐下降。免疫抑制组小白鼠在卵囊持续期不断有死亡但无腹泻症状。试验结果表明,用这2种免疫抑制方法,均能成功感染人源隐孢子虫,但通过灌服地塞米松可使小白鼠获得更高的OPG(每克粪便中的卵囊数)值和更长的排卵囊持续期。     

不同感染剂量对毒害艾美耳球虫繁殖力的影响

为研究不同感染剂量对毒害艾美耳球虫繁殖力的影响,设4个感染剂量组:500、2 500、5 000和10 000个孢子化卵囊/鸡,每组5只23日龄雏鸡,经鸡嗉囊接种卵囊。感染后鸡粪便中出现卵囊起至第16天,每天用麦克马斯特氏法对各组粪便中卵囊进行计数;在感染后第16天扑杀鸡,取盲肠进行卵囊计数。结果显示,各试验组鸡均无发生死亡,但10 000个卵囊感染组的临床症状最为严重;感染后144 h粪便中查见卵囊,500、2 500和5 000个卵囊感染组均出现2个排卵囊峰值,10 000个卵囊感染组只出现1个峰值,在第7～13天产出的卵囊量均占总产量的94.74%以上;每鸡粪便中排出的卵囊数随感染剂量的增加而增多,但单个卵囊的产量随感染剂量的增加而减少;感染后第16天盲肠中卵囊数不到总卵囊量的1%。结论:在疫苗生产或增殖传代时,感染剂量可选择10 000个卵囊/鸡,在感染后第7～13天收集粪便中卵囊。     

苏云金芽胞杆菌伴胞晶体蛋白对猪体内蛔虫的作用及其血液生理生化指标的分析

感染性猪蛔虫卵以每头份3000个卵的量感染断奶仔猪，于第3天开始肌肉注射不同剂量苏云金芽胞杆菌晶体蛋白（insecticidal crystal proteins，ICPs），每天1次，连续4d。同时测定猪血液生理生化指标，饲喂2个月后收集猪粪便计算虫卵数。结果显示，感染猪出现咳嗽、发热等临床症状，GOT、GPT、ALP、LDH等指标明显升高，经ICPs治疗后又恢复正常。粪便检查，ICPs高剂量组（16．08mg）的EPG（每克粪便虫卵数）为0，而ICPs低剂量组（9．45mg）的EPG为394，未经ICPs作用对照组EPG为2113，差异极显著（P〈0．01），证明ICPs对猪体内猪蛔虫具有较好的杀灭作用。     

毒害艾美耳球虫-田间分离株的致病性试验

毒害艾美耳球虫扬州田间分离株以不同的剂量(10 000,30 000,50 000,70 000,90 000个卵囊/羽)感染28日龄黄羽肉雏鸡,以平均增重、死亡率、病变记分等指标评价其致病性。结果显示,除10 000个卵囊组外,其余4个剂量组均显著影响增重(P<0.05),并引起鸡的死亡,死亡率分别为37.5%～50%、37.5%～50%、62.5%、75%～87.5%;各感染组均出现肠道病变,其中10 000个卵囊组的病变值显著小于其余4个剂量组(P<0.05),但与不感染对照组相比有显著差异(P<0.05)。结论表明,该毒害艾美耳球虫田间分离株有很强的致病性。     

云南贯众化合物2对猪蛔虫驱除作用效果观察

考察云南贯众化合物2对猪蛔虫驱除作用。以感染虫卵量约为6×105个/头的自然感染蛔虫病猪作为试验动物,试验过程中每天观察其临床表现,并于感染后2个月对粪便进行蛔虫卵检查和记数,60 d后粪检虫数达7 000个/g则可作为猪蛔虫病模型的供试动物;云南贯众化合物2作为供试药物。结果表明,云南贯众化合物2驱除猪蛔虫作用效果明显,且具有吸收分布快、消除缓慢和生物利用率高等特点,其驱虫效果确实可靠。     

微小隐孢子虫感染绵羊模型的建立

为建立稳定、可靠的微小隐孢子虫(Cryptosporidium parvum)感染绵羊模型,将4只2日龄绵羊分成2组,分别经口接种1×106个(低剂量组)和1×107个(高剂量组)的C.parvum卵囊,观察绵羊每日精神状况,并采集粪便样品,提取DNA,用基于TaqMan探针的实时荧光定量PCR方法进行检测,计算每日排卵囊数量。结果表明,两组羔羊均从第4天开始出现精神沉郁、食欲下降及严重的腹泻症状,镜检发现有大量的C.parvum卵囊排出,其中高剂量组的2只羔羊在感染后的第10天死亡。TaqMan实时荧光定量PCR检测结果显示,两组羔羊均从第1天开始有少量的卵囊排出,从第5天开始增多。其中低剂量组的1#羔羊第9天达到高峰,2#羔羊第7天达到高峰,随后排卵囊量开始下降,2只羔羊直到实验结束的第36天仍有卵囊排出,并且首次发现羔羊感染C.parvum后出现3个排卵囊高峰期。高剂量组的2只羔羊均在第6天达到高峰,其中3#羔羊第7天仍然有大量卵囊排出,4#羔羊第7天和第8天仍有大量卵囊排出,随后开始下降;高剂量组羔羊高峰期排卵囊数量明显高于低剂量组羔羊高峰期排卵囊数量。对死亡羔羊进行的肠道组织学观察,发现虫体寄生部位肠黏膜层出现大面积实质细胞脱落,局部可见肠腺数量减少,被增生的结缔组织取代。提取死亡羔羊肠道内容物和粪便DNA,进行套式PCR扩增,经测序鉴定,证实为C.parvum感染,与羔羊接种的虫种一致。上述结果表明,接种1×106个C.parvum卵囊,绵羊出现明显的临床症状,并伴有大量的卵囊排出,可以作为C.parvum的感染模型;而接种1×107个C.parvum卵囊,绵羊会发生死亡,但是能够排出更多的卵囊,适合进行隐孢子虫的繁殖试验。为进一步利用该模型研究C.parvum的致病机理、疫苗和药物筛选奠定了良好的基础。     

蜂王浆中活性小分子物质BHT对小白鼠抗衰老作用的影响

通过对6组由D-半乳糖造衰老模型的小白鼠,分别采用每天灌胃蜂王浆(0.15g/mL)、灌胃BHT(500mg/L)、灌胃蜂王浆加低剂量BHT(100mg/L)、灌胃蜂王浆加中剂量BHT(500mg/L)、灌胃蜂王浆加高剂量BHT(800mg/L),以及空白对照处理,连续1个月。结果表明,与空白对照组小白鼠比较,饲喂BHT剂量组、低、中剂量组(蜂王浆 BHT)小白鼠肝脏中丙二醛含量显著下降。饲喂BHT、中剂量组(蜂王浆 BHT)小白鼠血中SOD的含量及活性显著上升。饲喂BHT、低、中、高剂量组(蜂王浆 BHT)小白鼠血中GSH-PX的含量及活性上升。     

杠板归水浸液对小白鼠生长性能、血液生化指标及脏器病变的影响

试验旨在研究杠板归水浸液对小白鼠的毒性作用.将小白鼠分为雌鼠组、雄鼠组、对照组,给雌鼠组和雄鼠组饮用杠板归水浸液,观察小鼠状态、重量、摄食量、饮水量.7周后,血液生化检查小白鼠肝肾功能,剖检观察小白鼠的病理变化.杠板归水浸液浓缩灌胃小白鼠,按药物剂量0.75、0.5、0.35 g分别给小白鼠灌胃,观察小白鼠活动状态、死...     

和缓艾美耳球虫致病性研究

对新分离的和缓艾美耳球虫进行了致病性研究.结果表明,21日龄雏鸡感染1000个和5000个孢子化卵囊未见异常表现,肠道未发现肉眼可见的病理变化.20 000个卵囊感染可引起轻微病变,100 000个和500 000个卵囊感染能产生较明显的致病作用,与对照组相比增重分别为70.3%和56.8%.根据肠道病变记分标准,肠道有明显可见的病变,所有试验鸡均未出现死亡.     

11株巨型艾美耳球虫繁殖力的比较研究

用巨型艾美耳球虫扬州株、南通株、连云港株、苏州株、凤阳株、青岛株、福州株、龙岩株、广州株、上海株和美国株孢子化卵囊100个/只或10 000 个/只,经嗉囔接种7 日龄或21 日龄无球虫黄羽肉公雏,以麦克马斯特法对感染后第6 天至第14 天间每天24 h排出的卵囊计数并进行统计分析。结果表明,各虫株的排卵囊量有差异,100个/只卵囊感染7日龄雏鸡时,广州株和凤阳株排卵囊量最多,上海株和苏州株排卵囊量最少;100个/只卵囊感染21 日龄雏鸡时,扬州株排卵囊量最多,上海株排卵囊量最少;10 000 个/只卵囊感染21 日龄雏鸡时,苏州株排卵囊量最多,连云港株和扬州株的排卵囊量最少;排卵囊量随着感染剂量的增加或鸡日龄的增大而增多;在同一感染剂量时,福州株和连云港株增加最多,上海株和苏州株增加最少;在同一感染鸡日龄时,苏州株和上海株增加最多,南通株和扬州株增加最少;各虫株的排卵囊规律极相似,在感染后第7 天排卵囊量达峰值,第8 天、第9 天排出的卵囊量显著减少,第10天排出的卵囊量仅占总量的2%,第14天接近于0%;第6天至第8天排出的卵囊量占总量的87%~99%。     

Establishment of Ascaris suum in the pig: development of immunity following a single primary infection

Development of immunity after a single primary infection of Ascaris suum in pigs was investigated with regard to the worm population dynamics of a superimposed A. suum infection, host immune response and gross liver pathological changes. Group A was given a primary infection of 60,000 infective A. suum eggs and group B was left uninfected. Four weeks later both groups A and B were inoculated with 1,000 A. suum eggs, and subgroups were slaughtered 7, 14 and 21 days post challenge infection (p.c.i.). An uninfected control group C was slaughtered on day 21 p.c.i. The challenge worm recovery in group A was reduced compared to group B by 12%, 50% and 75% on day 7, 14 and 21 days p.c.i., respectively. In both groups was the expulsion of worms initiated between day 14 and 21 p.c.i. However, in group A the worms were recovered more posteriorly in the small intestine and 21 days p.c.i. the mean worm length was significantly shorter than in group B (p = 0.01). The results above were associated with significantly higher (p < 0.05) antibody response and higher eosinophil counts in group A compared to group B. The present results suggest that the larval growth and survival of a challenge infection are decreased, probably due to higher antibody and eosinophil attack during the migratory phase.     

A comparison of the efficacy of two ivermectin formulations against larval and adult Ascaris suum and Oesophagostomum dentatum in experimentally infected pigs

A study was conducted to evaluate and compare the efficacy of two injectable formulations of ivermectin (IVM-1 and IVM-2) at a dose rate of 0.3 mg/kg bodyweight versus placebo in the treatment and control of larval and adult stages of Ascaris suum and Oesophagostomum spp. in experimentally infected pigs. Seventy helminth free pigs were allocated on a liveweight basis to 7 groups each comprising 10 pigs (A-G). Group A served as an untreated control group. Groups B and C were used to investigate the efficacy of both formulations against adult stages of A. suum and Oesophagostomum spp., Groups D and E for efficacy against larval stages of A. suum and Groups F and G for efficacy against larval stages of Oesophagostomum spp. Pigs of groups A, B, C, D and E were infected on Day-0 with 1000 infective A. suum eggs each. Infective larvae of Oesophagostomum spp. (10,000/pig) were given on Day-0 to pigs of Groups F and G and on Day-21 to pigs of Groups A, B and C. Treatment was given to pigs of Group A (saline as placebo) on Day-7 and -28, IVM-1 to pigs of Group F on Day-7, pigs of Group D on Day-14 and pigs of Group B on Day-49. IVM-2 was given to pigs of Group G on Day-7, Group E on Day-28 and Group C on Day-49. Pigs of Groups F and G were sacrificed on Day-28, pigs of Groups A, D and E on Day-49 and pigs of Groups B and C on Day-56. Post mortem worm counts showed the following efficacies: (IVM-1) against larval A. suum 100%, against adult A. suum 94.4%, against larval Oesophagostomum spp. 52.0% and against adult Oesophagostomum spp. 83.0%. (IVM-2) against larval A. suum 100%, against adult A. suum 90.3%, against larval Oesophagostomum spp. 94.0% and against adult Oesophagostomum spp. 94.7%.     

Concurrent Ascaris suum and Oesophagostomum dentatum infections in pigs.

The aim of this study was to examine interactions between Ascaris suum and Oesophagostomum dentatum infections in pigs with regard to population dynamics of the worms such as recovery, location and length; and host reactions such as weight gain, pathological changes in the liver and immune response. Seventy-two helminth-na?ve pigs were allocated into four groups. Group A was inoculated twice weekly with 10000 O. dentatum larvae for 8 weeks and subsequently challenge-infected with 1000 A. suum eggs, while Group B was infected with only 1000 A. suum eggs; Group C was inoculated twice weekly with 500 A. suum eggs for 8 weeks and subsequently challenge-infected with 5000 O. dentatum larvae, whereas Group D was given only 5000 O. dentatum larvae. All trickle infections continued until slaughter. Twelve pigs from Group A and B were slaughtered 10 days post challenge infection (p.c.i.) and the remaining 12 pigs from the each of the four groups were slaughtered 28 days p.c.i.. No clinical signs of parasitism were observed. The total worm burdens and the distributions of the challenge infection species were not influenced by previous primary trickle-infections with the heterologous species. Until day 10 p.c.i. the ELISA response between A. suum antigen and sera from the O. dentatum trickle infected pigs (Group A) pigs were significantly higher compared to the uninfected Group B. This was correlated with a significantly higher number of white spots on the liver surface both on Day 10 and 28 p.c.i. in Group A compared to Group B. The mean length of the adult O. dentatum worms was significantly reduced in the A. suum trickle infected group compared to the control group. These results indicate low level of interaction between the two parasite species investigated.     

Hepatic lesions caused by migrating larvae of Ascaris suum in chickens

Group A consisted of chickens infected with a single dose of Ascaris suum and group B of chickens infected with two successive doses. At days 1, 3, 7, 14 and 21 after the first or second infection dose, six chickens from each group were sacrificed. In both groups, larvae were recovered from the livers on days 1, 3, and 7 and lungs on days 3 and 7. No larvae were detected in chickens on day 14. Clear white lesions were noticed only on the livers from chickens of group B at day 7 but had disappeared at day 14. A comparison with group B showed mild histological changes that developed relative to the livers from group A.     

Evidence of interaction between Ascaris suum and Metastrongylus apri in experimentally infected pigs

A study has been carried out with the aim to determine possible interactions between Ascaris suum and Metastrongylus apri under experimentally infected pigs. Twenty-eight Iberian pigs were allocated into four groups. Group 1 was inoculated with 5000 infective A. suum eggs; group 2 received concurrently 5000 infective A. suum eggs and 5000 infective M. apri larvae; group 3 received 5000 infective M. apri larvae; group 4 served as uninfected controls. In each group, pigs were necropsied on day 7 (n = 4) and day 28 (n = 3) post-infection (p.i.). Pigs with single M. apri infections showed earlier and more severe respiratory symptoms compared to pigs with mixed infection, while no clinical signs were observed in pigs single infected with A. suum. Mean burdens of immature A. suum and immature and adult M. apri were reduced in pigs with concomitant infection both on day 7 and 28 p.i., respectively. In contrast, the number of white spots was significantly increased on day 7 in pigs with mixed infection. In addition, pigs of group 1 showed the highest eosinophil levels in blood compared to pigs in groups 2 (intermediate levels) and 3 (moderate levels). The results suggest an antagonistic interaction between A. suum and M. apri in concomitantly infected pigs.     

Seminal vesicle growth induced by Ascaris suum infection

This study was designed to determine the effect of Ascaris suum infection upon growth of mouse vesicular glands. Mice were infected with varying dosages of A. suum eggs and killed after six weeks. Results indicated a dose dependent increase in seminal vesicle weight, independent of total body weight.     

Immunization of pigs against Ascaris suum by sequential experimental infections terminated with fenbendazole during larval migration

Three experimental infections of weaning pigs with 2000 embryonated Ascaris suum eggs each, 11 days apart, followed each time by fenbendazole treatment, produced a significant host response when compared with similar infected or uninfected control pigs as assessed by response to a subsequent challenge with 100 embryonated A. suum eggs. The response elicited from pigs treated with fenbendazole on either 2, 3, and 4 days or, 6, 7, and 8 days after each experimental infection was expressed as a reduction in the number of pigs with A. suum, in the number of worms per pig, in the weight of male and female worms, and in the length of male and female worms. No differences in average daily weight gain, feed-conversion efficiency or histology of lungs and liver were noted among the 4 treatment groups.     

Concurrent infection with Trichinella spiralis and other helminths in pigs

The aim of this study was to investigate possible influence of different helmintosis in the development of Trichinella spiralis in experimental infected pigs. Forty-two Iberian pigs were allocated to six groups. Three groups were single inoculated with Ascaris suum, Metastrongylus apri or T. spiralis, respectively. Two groups were co-infected with T. spiralis and A. suum or T. spiralis and M. apri, respectively, while the last group included uninfected control pigs. Clinical signs were only observed in pigs with single or concurrent M. apri infections, with more severe respiratory symptoms in pigs with mixed M. apri infection. The number of A. suum and M. apri lung larvae, intestinal larvae of A. suum and adult M. apri were reduced in pigs with mixed Trichinella infections compared to pigs with single infections. In contrast, the number of liver white spots was higher in pigs with mixed infections. While T. spiralis muscular larval burdens were increased in pigs concomitantly infected with M. apri, they were reduced in pigs concomitantly infected with A. suum, compared to pigs receiving single infections with either of these helminths. Pigs with single or mixed A. suum infections showed higher eosinophil levels compared to the remaining groups. IgGt, IgG1, IgG2 and IgM against T. spiralis antigen could not be detected in pigs with single Ascaris or Metastrongylus infections, indicating that no cross-antibodies were produced. IgGt, IgG1 and IgM antibodies were detected earlier and generally at higher levels in mixed T. spiralis infections compared to single T. spiralis infections. The results suggest that T. spiralis had a low synergistic interaction with M. apri in concomitantly infected pigs, and an antagonistic interaction in concurrent infection with A. suum.     

Evaluation of fenbendazole as an extended anthelmintic treatment regimen for swine

Fenbendazole was given in the feed to swine at a cumulative dosage of 9 mg/kg of body weight over a period of 3, 6, and 12 days to compare efficacy. Four treatment groups of ten 2- to 3-month-old pigs each, with a mean of 15 kg of body weight per group, received 3 mg of fenbendazole/kg/day for 3 days, 1.5 mg/kg/day for 6 days, 0.75 mg/kg/day for 12 days, and no medication. Medicated feed was scheduled so that all treated pigs reached the last day of treatment on the same day, thus making the time between the last treatment and necropsy equal for all groups. Ascaris suum and Trichuris suis were the target species, their presence before treatment being determined by fecal egg counts and at necropsy by worm counts. At necropsy, 9 control pigs were infected with A suum (mean of 18.0 worms/pig), and all control pigs had T suis infection (mean of 36.5 worms/pig). All 3 treatment schedules were 100% effective in removal of A suum; and for T suis, the 3-day regimen was 100% effective, the 6-day regimen, 99.2%, and the 12-day regimen, 91.0%.