A hundred years of controversy about the taxonomic status of Echinococcus species

The parasitic diseases which we know today as cystic and alveolar echinococcosis are zoonoses known since antique times, and 1855, respectively. Whether the two clinically and morphologically distinct diseases were caused, according to a “unicistic” and a “dualistic” theory, by only one or two different cestode species was the subject of a fierce, 100 years long debate involving scientists from many countries. The natural life cycle of Echinococcus granulosus was fully clarified in 1855 after successful animal experiments. In contrast, the natural final and intermediate hosts of Echinococcus multilocularis remained unknown, and the advocates of either theory had to draw on a number of surrogate arguments to defend their positions. The seesaw of reasoning and mutual defeats of the two theories, and the final recognition of E. multilocularis as an independent species in the 1950s are described in this article.     

Hepatic Echinococcal Cysts: A Review

Cystic echinococcosis (CE) is a widely endemic helminthic disease caused by infection with metacestodes (larval stage) of the Echinococcus granulosus tapeworm. E. granulosus are common parasites in certain parts of the world, and are present on every continent with the exception of Antarctica. As a result, a large number of people are affected by CE. The increased emigration of populations from endemic areas where prevalence rates are as high as 5–10% and the relatively quiescent clinical course of CE pose challenges for accurate and timely diagnoses. Upon infection with CE, cyst formation mainly occurs in the liver (70%). Diagnosis involves serum serologic testing for antibodies against hydatid antigens, but preferably with imaging by ultrasound or CT/MRI. Treatment methods include chemotherapy with benzimidazole carbamates and/or surgical approaches, including percutaneous aspiration injection and reaspiration. The success of these methods is influenced by the stage and location of hepatic cysts. However, CE can be clinically silent, and has a high risk for recurrence. It is important to consider the echinococcal parasite in the differential diagnosis of liver cystic lesions, especially in patients of foreign origin, and to perform appropriate long-term follow-ups. The aim of this review is to highlight the epidemiology, natural history, diagnostic methods, and treatment of liver disease caused by E. granulosus.     

Characterization of polysaccharides of the eggs and adults of Hymenolepis diminuta

Polysaccharides and other complex carbohydrates were released by proteolysis of the chloroform-methanol insoluble residue of 10 day-old worms and eggs of Hymenolepis diminuta. Gas-liquid chromatographic analysis of alditol acetate derivatives of monosaccharides released from the polysaccharides by hydrolysis revealed that in the 10 day-old worm, glucose was the most abundant sugar, followed by galactose, glucosamine, galactosamine, fucose and possibly rhamnose. Mannose was least abundant and xylose was absent. In the egg, glucose and galactose were equally abundant, followed by the same sugars found in 10 day-old worms, and xylose was present. Uronic acid was detected in both fractions by specific chemical tests. None of the saccharide material from eggs and worms was susceptible to degradation by Streptomyces hyaluronidase, chondroitinase AC, and slightly susceptible to chondroitinase ABC, as shown by electrophoretic analysis on composite 2.2% acrylamide-agarose slab gels and $\text{4.5}\text{12.5\%}$ polyacrylamide gels before and after enzymatic treatment. One of the gel-separable bands, however, was degradable by both nitrous acid and Flavobacterium heparinase. Both bands from eggs were degradable by nitrous acid. These results suggest that eggs contain heparin and/or heparan sulfate and perhaps dermatan sulfate and that 10 day old worms also have these polyglycans but possibly not chondroitin sulfate or hyaluronic acid.     

Glycosaminoglycans of tegumental fractions of Hymenolepis diminuta

The teguments of 6 and 10 day-old Hymenolepis diminuta were removed with Triton X-100 and separated into brush border and vesicular fractions by differential centrifugation. Glycosaminoglycans (GAG) isolated from these tissues and from the denuded carcass were treated with specific GAG-degrading enzymes and other chemical agents and analyzed by sodium dodecyl sulfate-polyacrylamide, agarose gel and cellulose acetate electrophoresis. Both 6 and 10 day-old worm carcasses contained chondroitin sulfate, heparin/heparan sulfate and hyaluronic acid. The 10 day-old worm brush border and vesicle fractions contained chondroitin sulfate but no heparin-like material. Colorimetric analysis showed that the carcasses of both 6 and 10 day-old worms contained uronic acid. About 98% of the detectable uronic acid of 10 day-old worms was found in the carcass, and only 2% in the brush border fraction. No uronic acid was detected in the other tegumental fractions.     

Naturally-induced endocrine disruption by the parasite Ligula intestinalis (Cestoda) in roach (Rutilus rutilus)

Fish represent the most frequently used vertebrate class for the investigation of endocrine disruption (ED) in wildlife. However, field studies are complicated by exposure scenarios involving a variety of anthropogenic and natural influences interfering with the endocrine system. One natural aspect rarely considered in ecotoxicological studies is how parasites modulate host physiology. Therefore, investigations were carried out to characterise the impacts of the parasitic tapeworm Ligula intestinalis on plasma sex steroid levels and expression of key genes associated with the reproduction in roach (Rutilus rutilus), a sentinel species for wildlife ED research. Parasitisation by L. intestinalis suppressed gonadal development in both genders of roach and analysis of plasma sex steroids revealed substantially lower levels of 17β-oestradiol (E2) and 11-ketotestosterone (11-KT) in infected females as well as E2, 11-KT, and testosterone in infected males. Consistently, in both, infected females and males, expression of the oestrogen dependent genes such as vitellogenin and brain-type aromatase in liver and brain was reduced. Furthermore, parasitisation differentially modulated mRNA expression of the oestrogen and androgen receptors in brain and liver. Most prominently, liver expression of oestrogen receptor 1 was reduced in infected females but not in males, whereas expression of oestrogen receptor 2a was up-regulated in both genders. Further, insulin-like growth factor 1 mRNA in the liver was increased in infected females but not in males. Despite severe impacts on plasma sex steroids and pituitary gonadotropin expression, brain mRNA levels of gonadotropin-releasing hormone (GnRH) precursors encoding GnRH2 and GnRH3 were not affected by L. intestinalis-infection. In summary, the present results provide basic knowledge of the endocrine system in L. intestinalis-infected roach and clearly demonstrate that parasites can cause ED in fish.     

江苏江都县吴堡乡缩小膜壳绦虫流行病学调查

本文报告１９９３年在江苏江都县吴堡乡进行了缩小鹏壳绦虫流行病学调查，采用定量透明法和饱和盐水浮聚法检查１９２１份粪样，阳性２２例．感染率１．１％，其中６例混合肠道线虫感染；采用饱和硝酸钠浮聚法检测庭院士样４５０份，阳性６份，污染率１．３％．同时证实家鼠存在感染，缩小膜壳绦虫在当地人、鼠之间相互传播构成了流行的可能性。     

云南兰坪地区带绦虫rDNA—ITS PCR—RFLP分析

目的对云南兰坪地区带绦虫种类进行鉴定。方法分别选取云南兰坪地区带绦虫(LP株)、猪带绦虫(ZD株)、牛带绦虫(ND株)和都匀亚洲带绦虫(DY株)成虫孕节3片(ZD株、ND株、DY株均为标准对照),抽提基因组DNA,PCR扩增rDNA-ITS片段,用限制性内切酶Dde I对扩增片段作酶切分析。结果LP株rDNA-ITS片段PCR扩增产物经Dde I酶切后的图谱与DY株一致,与ND株和ZD株均不同。结论云南兰坪地区带绦虫(LP株)与DY株相似,同属于亚洲带绦虫。PCR-RFLP适用于带绦虫病的流行病学调查和临床诊断。     

Unusual colonoscopy finding： Taenia saginata proglottid

Infection with tapeworms is a major problem in many parts of the world. Patients may be asymptomatic or have a significant morbidity depending on the species. Infection with Taenia species is sometimes found by expulsion of eggs or proglottids in stool. Species specific diagnosis of Taenia is difficult, but possible. We present a case of Taenia saginata incidentally discovered, and risk factors for transmission, diagnosis, symptoms, and treatment.     

绦虫永久染色标本的制作技术

目的制作绦虫玻片染色标本用于教学和科研。方法用墨汁染色法制作绦虫妊娠节片玻片标本,卡红染色法制作绦虫成熟节片、头节和囊尾蚴玻片标本。结果妊娠节片、成熟节片、头节和囊尾蚴经染色制片后特征结构明显可见。如妊娠节片染色标本清晰可见染成墨汁颜色的子宫主干和分支状的子宫侧支,节片一侧边缘中部可见突出的生殖腔;成熟节片染色标本均染成红色,内有着色更深的雌雄生殖系统各一套。结论墨汁染色和卡红染色制作带绦虫染色标本效果好,可永久保存。