New imaging diagnostics of liver echinococcosis

Cystic and alveolar echinococcosis, parasitic diseases, caused in humans by the larval stage of tapeworm Echinococcus granulosus and E. multilocularis are rare diseases in Poland. We have diagnosed 71 patients with cystic echinococcosis and 10 patients with alveolar echinococcosis during last 12 years. Echinococcosis still create significant diagnostic difficulties, particularly alveolar one. Progress and actually available radiological imaging techniques, which can be applied in the cystic and alveolar echinococcosis diagnostics, are presented. Ultrasound appearance, CT, MRI images are described. Own experience with Proton Magnetic Resonans Spectroscopy in two patients with recurrent alveolar echinococcosis are presented.     

两种致病人体棘球绦虫动物宿主感染及影响因素研究进展

棘球蚴病是由棘球绦虫幼虫感染所致的一种危害严重的人兽共患寄生虫病。棘球绦虫生活史可涉及多种动物宿主,如有蹄类动物、啮齿类动物等中间宿主和食肉类动物终末宿主。自然界动物宿主间细粒棘球绦虫及多房棘球绦虫生活史循环与人体棘球蚴病传播密切相关。本文综述了近年来国内外有关细粒棘球绦虫和多房棘球绦虫主要动物宿主分布及感染的影响因素研究进展,旨在为开展棘球蚴病精准防治提供参考。     

复杂性肝棘球蚴病外科治疗策略研究进展

肝棘球蚴病是一种由棘球属绦虫幼虫所致的人畜共患性疾病。我国主要致病绦虫类型为细粒棘球绦虫和多房棘球绦虫,分别引起细粒棘球蚴病和多房棘球蚴病。目前,棘球蚴病治疗已经取得重大进展,但对于部分就诊时已出现一种或多种并发症以及病灶侵及肝门、重要血管及胆管的复杂性棘球蚴病病例的治疗仍存在一定困难。本文根据近年来文献报道,结合临床经验,对复杂性肝棘球蚴病的外科治疗策略进行综述。［关键词］     

Hydatid lung disease (echinococcosis/hydatidosis)

Two Echinococcus species may exhibit medical relevance as causative agents of pulmonary forms of echinococcosis. Most importantly, infections with Echinococcus granulosus result in "cystic hydatid disease" or "cystic echinococcosis," which affects the lungs in a considerable ratio of cases. Echinococcus multilocularis, which causes "alveolar echinococcosis," affects the lungs relatively rarely and then usually upon metastasizing from primary hepatic lesions. Cystic echinococcus and alveolar echinococcus differ pathologically and clinically so greatly that they are considered separately in this article, although alveolar echinococcus is covered minimally because of its minor importance regarding lung infections.     

Molecular confirmation of human alveolar echinococcosis in Poland

Infections of humans with Echinococcus multilocularis, the causative agent of alveolar echinococcosis (AE), a zoonosis, have been described with increasing frequency in Poland since 1994. In the attempt to verify these reports, we analyzed specimens obtained from a representative group of Polish patients. Liver lesions in patients with AE that was diagnosed on the basis of results of histological and serological tests contained E. multilocularis DNA, as shown by the presence of specific microsatellite sequences and mitochondrial 12S rDNA. The same tests clearly distinguished between AE and cystic echinococcosis, which is caused by Echinococcus granulosus. These data are unequivocal proof that human infections with E. multilocularis occur in Poland.     

Hepatic echinococcosis: clinical and therapeutic aspects

Echinococcosis or hydatid disease (HD) is a zoonosis caused by the larval stages of taeniid cestodes belonging to the genus Echinococcus. Hepatic echinococcosis is a life-threatening disease, mainly differentiated into alveolar and cystic forms, associated with Echinoccus multilocularis (E. multilocularis) and Echinococcus granulosus (E. granulosus) infection, respectively. Cystic echinococcosis (CE) has a worldwide distribution, while hepatic alveolar echinococcosis (AE) is endemic in the Northern hemisphere, including North America and several Asian and European countries, like France, Germany and Austria. E. granulosus young cysts are spherical, unilocular vesicles, consisting of an internal germinal layer and an outer acellular layer. Cyst expansion is associated with a host immune reaction and the subsequent development of a fibrous layer, called the pericyst; old cysts typically present internal septations and daughter cysts. E. multilocularis has a tumor-like, infiltrative behavior, which is responsible for tissue destruction and finally for liver failure. The liver is the main site of HD involvement, for both alveolar and cystic hydatidosis. HD is usually asymptomatic for a long period of time, because cyst growth is commonly slow; the most frequent symptoms are fatigue and abdominal pain. Patients may also present jaundice, hepatomegaly or anaphylaxis, due to cyst leakage or rupture. HD diagnosis is usually accomplished with the combined use of ultrasonography and immunodiagnosis; furthermore, the improvement of surgical techniques, the introduction of minimally invasive treatments [such as puncture, aspiration, injection, re-aspiration (PAIR)] and more effective drugs (such as benzoimidazoles) have deeply changed life expectancy and quality of life of patients with HD. The aim of this article is to provide an up-to-date review of biological, diagnostic, clinical and therapeutic aspects of hepatic echinococcosis.     

Cestode infestations: hydatid disease and cysticercosis

Although humans can be definitive hosts for cestodes (tapeworms), major pathologic conditions occur during cestode larval stages when humans serve as the intermediate host for these parasites. The most relevant forms of human disease caused by cestode larvae are echinococcosis, caused by Echinococcus granulosus (cystic echinococcosis) and Echinococcus multilocularis (alveolar echinococcosis), and cysticercosis, caused by Taenia solium. These infections occur worldwide, but their relevance is particularly high in developing countries, where poor hygiene conditions facilitate the transmission of the parasites. The therapeutic approach is often complex, requiring surgery and/or chemotherapy or, in the case of cystic echinococcosis, percutaneous treatments.     

Pulmonary echinococcosis.

Echinococcosis or hydatid disease is caused by larvae of the tapeworm Echinococcus. Four species are recognised and the vast majority of infestations in humans are caused by E. granulosus. E. granulosus causes cystic echinococcosis, which has a worldwide distribution. Humans are exposed less frequently to E. multilocularis, which causes alveolar echinococcosis. E. vogeli and E. oligarthrus are rare species and cause polycystic echinococcosis. In cystic echinococcosis, humans are an accidental host and are usually infected by handling an infected dog. The liver and lungs are the most frequently involved organs. Pulmonary disease appears to be more common in younger individuals. Although most patients are asymptomatic, some may occasionally expectorate the contents of the cyst or develop symptoms related to compression of the surrounding structures. Other symptoms of hydatid disease can result from the release of antigenic material and secondary immunological reactions that develop from cyst rupture. The cysts are characteristically seen as solitary or multiple circumscribed or oval masses on imaging. Detection of antibody directed against specific echinococcal antigens is found in only approximately half of patients with pulmonary cysts. Surgical excision of the cyst is the treatment of choice whenever feasible.     

Short report: Inadequacy of yaks as hosts for the sheep dog strain of Echinococcus granulosus or for E. Multilocularis

Hydatid disease (echinococcosis) has a two-host cycle involving the domestic dog and grazing animals. Humans are also infected by the dog. Both unilocular (Echinococcus granulosus in yaks, sheep, and goats) and multilocular (alveolar) (E. multilocularis in hares and rodents) hydatids are common in western Sichuan in the People's Republic of China. Humans and dogs are equally infected with both species. Many yaks (Bos grunniens) were found with multilocular cysts that visually were deemed to be E. multilocularis. However, a histologic and molecular study showed that they were actually E. granulosus. No infective cysts were found in 125 necropsied yaks. We conclude that the yak is an inadequate and dead-end host for the sheep dog (G1) strain of Echinococcus granulosus and also for E. multilocularis.     

Serological prevalence of echinococcosis and risk factors for infection among children in rural communities of southern Ningxia, China

Objective  To assess the usefulness of serology as an indicator of Echinococcus transmission for developing preventive measures against echinococcosis in rural communities.
Methods  Cross-sectional survey in 2002 among 861 children aged 7 to 18 years in Xiji County, Ningxia, China. Before ultrasound abdominal examination, a questionnaire was used to identify socioeconomic, sanitary and hygiene risk factors for echinococcal infection; filter paper blood samples were collected from each child for specific antibody detection using EmP ( Echinococcus multilocularis ) and EgB ( Echinococcus granulosus ) antigens.
Results  Transmission of both E. multilocularis and E. granulosus occur in this area. Serological prevalence was far higher than disease prevalence in this age range. We found no gender-related differences of seroprevalence among the children, suggesting an equal chance of exposure to echinococcal egg-contaminated environments. The seroprevalence distribution was associated with changes in the ecology of wild hosts for E. multilocularis contamination, and with changes in socio-geographic features of the communities for E. granulosus contamination.
Conclusions  Serological data obtained for children in mass surveys of echinococcosis appear to be a comprehensive and useful tool to monitor changes of transmission dynamics in humans and provide 'warning signals' to decision makers for the instigation of specific control measures against the disease.     

Worldwide epidemiology of liver hydatidosis including the Mediterranean area

The worldwide incidence and prevalence of cystic echinococcosis have fallen dramatically over the past several decades. Nonetheless, infection with Echinococcus granulosus (E. granulosus) remains a major public health issue in several countries and regions, even in places where it was previously at low levels, as a result of a reduction of control programmes due to economic problems and lack of resources. Geographic distribution differs by country and region depending on the presence in that country of large numbers of nomadic or semi-nomadic sheep and goat flocks that represent the intermediate host of the parasite, and their close contact with the final host, the dog, which mostly provides the transmission of infection to humans. The greatest prevalence of cystic echinococcosis in human and animal hosts is found in countries of the temperate zones, including several parts of Eurasia (the Mediterranean regions, southern and central parts of Russia, central Asia, China), Australia, some parts of America (especially South America) and north and east Africa. Echinococcosis is currently considered an endemic zoonotic disease in the Mediterranean region. The most frequent strain associated with human cystic echinococcosis appears to be the common sheep strain (G1). This strain appears to be widely distributed in all continents. The purpose of this review is to examine the distribution of E. granulosus and the epidemiology of a re-emerging disease such as cystic echinococcosis.     

Hospital and community surveys reveal the severe public health problem and socio-economic impact of human echinococcosis in Ningxia Hui Autonomous Region, China

A comprehensive study of human echinococcosis (caused by Echinococcus granulosus or E. multilocularis), including assessment of hospital records, community surveys and patient follow-up, was conducted in Ningxia Hui Autonomous Region (NHAR), China. In contrast to hospital records that showed 96% of echinococcosis cases were caused by cystic echinococcosis (CE), 56% of cases detected in active community surveys were caused by alveolar echinococcosis (AE). The AE and CE cases co-existed frequently in the same village, even occurring in the same patient. A serious public health problem caused by echinococcosis was evident in southern NHAR, typified by: a long diagnostic history for both AE and CE (7.5 years) compared with a shorter treatment history (4.7 years); a significant mortality rate (39%) caused by AE in one surveyed village, where patients had no previous access to treatment; family aggregation of CE and AE cases; a high proportion of both AE (62.5%) and CE (58%) in females; a high rate of recurrent surgery (30%) for CE demonstrated by surgical records; and frequent symptomatic recurrences (51%) because of discontinuous or sporadic access to chemotherapy for AE. The disease burden for both human AE and CE is thus very severe among these rural communities in NHAR, and this study provides the first attempt to determine the costs of morbidity and surgical intervention of human CE and AE cases both at the hospital and community level in this setting. This information may be useful for assessing the cost effectiveness of designing effective public health programs to control echinococcosis in this and other endemic areas in China and elsewhere.     

Echinococcus multilocularis

PURPOSE OF REVIEW: Echinococcus multilocularis is a tapeworm of foxes that may cause a zoonotic infection resulting in a highly pathogenic and potentially fatal chronic liver infestation called human alveolar echinococcosis. Radical liver resection currently offers the only potential cure. Although alveolar echinococcosis is a rare parasitic disease that is restricted to transmission in the northern hemisphere, the parasite is geographically widespread being distributed from Alaska, across Canada and north central USA, through northern Europe and Eurasia to Japan. The present review summarizes the background to this helminthic infection and recent contributions in areas of pathology, diagnosis, treatment and transmission. RECENT FINDINGS: Concern is growing in Europe that the prevalence and distribution of E. multilocularis in red foxes has increased significantly in the last 10-15 years. A retrospective analysis revealed >550 cases of human alveolar echinococcosis diagnosed between 1982-2000, with the majority in France, Germany and Switzerland. Human prevalence rates >3% occur in central northwest China and the disease is of public health concern in northern Japan. Improvements in immunodiagnosis with native and recombinant antigens have enabled more accurate confirmation of hepatic image findings, while development of in-vitro culture of metacestode tissues provides a useful model for screening new anti-alveolar echinococcosis drugs as alternatives to albendazole and surgery. Recombinant molecules from the oncosphere and metacestode stages have shown potential as vaccine candidates. New tools of coproantigen and copro-DNA detection for vulpine infections have proved highly beneficial in epidemiological and transmission ecology studies, as has a landscape ecology approach to develop risk models for communities in endemic areas. SUMMARY: It is possible that human AE will become an emergent zoonosis in some regions of Europe and Eurasia. Improvements in diagnostic and treatment approaches are being investigated. Further understanding of host immune responses will aid in characterization of disease pathology. Control of E. multilocularis in its natural cycles will be difficult due to the involvement of wild animal hosts, however use of anthelminthic baits and dosing of domestic dogs may reduce transmission at local scales.     

Dual infection of animal hosts with different Echinococcus species in the eastern Qinghai-Tibet plateau region of China

The eastern Qinghai-Tibet plateau of China is a highly endemic region of echinococcosis where Echinococcus granulosus sensu stricto (sheep strain), Echinococcus multilocularis, and Echinococcus shiquicus are distributed sympatrically. We developed a polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) method for the identification of the three species in this region. The PCR-RFLP showed the dual infection of animals with different Echinococcus spp. The first case was a domestic dog concurrently infected with adults of E. granulosus and E. multilocularis. The second case was a plateau pika (Ochotona curzoniae) harboring metacestodes of E. multilocularis and E. shiquicus in the liver. The high susceptibility of some mammalian hosts to the parasites and the high prevalence of the three co-endemic species probably increase the chance of mixed infections in the eastern Tibetan plateau.     

青海省动物棘球蚴病及棘球绦虫感染的流行病学调查

【提要】 采用解剖学方法和寄生虫学方法进行了棘球绦虫中间宿主和终末宿主调查，了解青海省动物棘球蚴病/棘球绦虫感染的流行现状。结果表明，青海省家畜棘球蚴病的流行有升高的趋势，主要畜种绵羊和牦牛的平均感染率达50%以上。野生中间宿主动物感染率以青南高原为最高，祁连山地域的犬、狼等终末宿主动物的感染率高于其他两个地形区。青海省棘球绦虫的生活史循环链复杂，动物感染率高，对人类健康构成威胁，应因地制宜地采取有效措施，加强动物棘球蚴病和棘球绦虫病的防治。     

利用细胞色素氧化酶亚单位Ⅰ分析青海藏区细粒棘球绦虫系统发育学

目的 囊型包虫病是一种广泛流行且危害严重的人兽共患寄生虫病。本文旨在分析流行于青南地区细粒棘球绦虫系统发育学及基因多态性。方法 本文利用线粒体 DNA细胞色素氧化酶亚单位 Ⅰ (COX Ⅰ )分子对收集到的流行于青海省的59例包虫病样本进行测序。总计71条序列(其中12条来自GenBank)碱基通过Clustal X软件比对,构建贝叶斯进化树。结果 流行于青海省包虫病样本大部分与细粒棘球绦虫G1型聚在一枝,还有三个样本与多房棘球绦虫(AB018440)聚在一枝。虽大部分棘球绦虫基因型属于G1型,但各自的基因型各不相同,具有丰富的多样性。结论 流行于青海省细粒棘球绦虫系统发育学比我们想象复杂。     

Past to present: echinococcosis in Turkey

Echinococcosis is a zoonotic infection caused by Echinococcus spp. and is one of the most important helminthic diseases worldwide. Two forms of echinococcosis occur in Turkey, i.e. Echinococcus granulosus and E. multilocularis. The life cycle of E. granulosus is predominantly in dogs and sheep, and most sheep farmers in Turkey keep a dog or two. Stray dogs are numerous and prevention or treatment of infection in these dogs is very difficult. Cystic echinococcosis (CE) occurs throughout Turkey whereas alveolar echinococcosis (AE) predominantly occurs in the eastern Anatolian region of the country. Both CE and AE are known to be endemic but few surveys have been performed. Most data on human CE and AE have been collected from hospital records. The first reference of echinococcosis, "Kyste hydatique multiloculaire", in Turkey dates as far back to 1872 by an Ottoman Physician, C.R. Katibian. The results of the first Turkish study on E. granulosus were published in 1928. According to Ministry of Health records, 21303 patients had operations to treat or confirm CE in the period 1987-1994 which corresponds to approximately 2663 patients per year. The estimated surgical case rate of CE is 0.87-6.6 per 100000 in Turkey. The prevalence of E. granulosus infection in dogs in Turkey is between 0.32 and 40% and varies widely with geographical location. The reported prevalence of CE in domestic animals in Turkey has ranged from 11.2 to 50.7% and has varied widely with geographical location. Although no detailed information has been published on AE in domestic and wild animals in Turkey, the main definitive and intermediate hosts of E. multilocularis are assumed to be rodents and red foxes, respectively. However, there has been only a single published report of E. multilocularis in a wild animal (fox) in the northwest in 1965 by Merdivenci. The first human case of AE in Turkey was reported by Mutlu in 1939, and total cumulative reported case number is 202 between 1980 and 1998.     

包虫病治疗进展

包虫病主要是由细粒棘球蚴和泡球蚴寄生于人体内引起的一种人兽共患病,严重危害人体健康和生命。目前包虫病的治疗主要以外科手术为主,药物治疗为辅。本文就包虫病的治疗进展作一综述。     

Cystic and alveolar echinococcosis: an epidemiological survey in a Tibetan population in southeast Qinghai, China

An epidemiological investigation on echinococcosis was made in Jiuzhi County of Qinghai Province, western China. Ultrasonography and an indirect hemagglutination test revealed a morbidity of 8.0% (124/1,549) and a seroprevalence of 25.8% (287/1,113), respectively, in the Tibetan population. The morbidity in herdsmen (16.6%) and Buddhist priests (15%) was significantly higher than that in other occupation groups (3.2%), and it was higher in females (9.8%) than in males (6.2%). The ultrasound images showed a coexistence of cystic echinococcosis (CE) and alveolar echinococcosis (AE), occupying 69 and 31% of the cases, respectively. An Echinococcus Western blot assay was performed as a serological backup test for differentiating CE and AE. The assay revealed that serum samples from most cases with a positive AE image showed a specific antibody against antigen bands at 16/18 kDa. Autopsy proved that 9 out of 12 stray dogs were infected with Echinococcus granulosus (n = 8) and E. multilocularis (n = 1). Inspection at the abattoirs demonstrated a hydatid rate of 78.5% in yaks and 82.6% in sheep. The data indicate that Jiuzhi County is an important endemic area for both CE and AE, in both human and animal populations.     

1995-2005年青海省棘球蚴病流行病学调查分析

目的分析1995—2005年青海省人与动物棘球蚴病的流行病学调查结果。方法人群棘球蚴病感染情况以Bu-ELISA、EM18-ELISA和B超、X线进行检查和评价。动物棘球蚴病／棘球绦虫感染调查采用解剖学方法和寄生虫学方法。结果①女性人群的血清阳性率和患病率显著高于男性人群（14．41％和4．81％、10．22％和3．25％）；随年龄增长，人群血清阳性率和患病率升高（见表5）；以牧民、喇嘛的血清阳性率和患病率最高（17．73％和9．33％、18．56％和10．0％）。②青海省人与动物棘球蚴病／棘球绦虫的血清阳性率和感染／患病率以青南高原的果洛、玉树、黄南三州最高（见表1、7、8），祁连山地和河湟谷地的海南、海北两州次之，海东地区、西宁及柴达木盆地的海西州较低。③青海省是以囊型棘球蚴病／细粒棘球绦虫为主的囊型和泡型棘球蚴病的混合流行区，并在其南部发现存在石渠棘球绦虫的动物感染。结论青海省棘球绦虫的生活史循环链十分复杂，家养动物相互之间、野生动物相互之间、家养动物和野生动物之间均参与其中。