European echinococcosis registry: human alveolar echinococcosis, Europe, 1982-2000

Multi-locus microsatellite analysis supports the hypothesis of an autochthonous focus of Echinococcus multilocularis in northern Italy

Echinococcus multilocularis is characterised by a wide geographical distribution, encompassing three continents (North America, Asia and Europe) yet very low genetic variability is documented. Recently, this parasite has been detected in red foxes (Vulpes vulpes) circulating in an Alpine region of Italy, close to Austria. This finding raised the question as to whether an autochthonous cycle exists in Italy or whether the infected foxes originated from the neighbouring regions of Austria. Studies have shown that multi-locus microsatellite analysis can identify genomic regions carrying mutations that result in a local adaptation. We used a tandem repeated multi-locus microsatellite (EmsB) to evaluate the genetic differences amongst adult worms of E. multilocularis collected in Italy, worms from neighbouring Austria and from other European and extra-European countries. Fluorescent PCR was performed on a panel of E. multilocularis samples to assess intra-specific polymorphism. The analysis revealed four closed genotypes for Italian samples of E. multilocularis which were unique compared with the other 25 genotypes from Europe and the five genotypes from Alaska. An analysis in the Alpine watershed, comparing Italian adult worms with those from neighbouring areas in Austria, showed a unique cluster for Italian samples. This result supports the hypothesis of the presence of an autochthonous cycle of E. multilocularis in Italy. EmsB can be useful for 'tracking' the source of infection of this zoonotic parasite and developing appropriate measures for preventing or reducing the risk of human alveolar echinococcosis.

Brain and lung metastasis of alveolar echinococcosis in a refugee from a hyperendemic area

Alveolar echinococcosis (AE) of the liver with cerebral and pulmonary metastasis was diagnosed in a Tibetan monk who initially presented with severe headache to an emergency department in Germany. Multiple lesions with perifocal oedema and severe compression of the third ventricle were seen with computed tomography (CT) of the brain. Glioma or cerebral metastasis of a hitherto undiagnosed abdominal or pulmonary malignancy was suspected. CT scans of the lung and liver demonstrated further tumorous masses. Magnetic resonance imaging of the brain revealed the cystic nature of the cerebral lesions and the patient had a highly positive serology for AE. The echinococcal aetiology of the brain lesions was confirmed by PCR for this refugee from an area where two disease entities, AE and cystic echinococcosis, are hyperendemic.

Collaborative control initiatives targeting zoonotic agents of alveolar echinococcosis in the northern hemisphere

Alveolar echinococcosis is one of the most important lethal zoonotic helminth infections in the northern hemisphere. Currently, the threat to public health is increasing, as evidenced by the rising prevalence rate of alveolar echinococcosis, as well as the invasion of urban areas by infected wild foxes. This threat is further increased due to the involvement of pet dogs, and probably cats, as emerging sources of infection. These increased threats to public health also have associated economic risks; therefore, there is a need for effective and sustainable methods of control. In this paper, initiatives to control alveolar echinococcosis by targeting its definitive hosts through anthelmintic baiting campaigns initiated by local residents who used local resources for bait production, distribution and collection of fecal samples for diagnosis are described. Further, when such distribution programs are coupled with the use of GIS-based maps, the optimum distribution of bait was obtained. These programs have also included the use of intravital diagnostic analyses of infection rates, which have been overseen by the Forum on Environment and Animals (FEA), and also allowed a nationwide monitoring of echinococcosis in difinitive hosts. In addition, a government initiative requiring mandatory reporting of echinococcosis in dogs to health authorities was recently initiated in Japan. Overall, the results of this study have shown that use of collaborative control initiatives targeting zoonotic agents of alveolar echinococcosis can be an effective method for reducing the threat of lethal echinococcosis in the northern hemisphere.

Landscape composition and spatial prediction of alveolar echinococcosis in southern Ningxia, China

BACKGROUND

Alveolar echinococcosis (AE) presents a serious public health challenge within China. Mass screening ultrasound surveys can detect pre-symptomatic AE, but targeting areas identified from hospital records is inefficient regarding AE. Prediction of undetected or emerging hotspots would increase detection rates. Voles and lemmings of the subfamily Arvicolinae are important intermediate hosts in sylvatic transmission systems. Their populations reach high densities in productive grasslands where food and cover are abundant. Habitat availability is thought to affect arvicoline population dynamic patterns and definitive host-intermediate host interactions. Arvicoline habitat correlates with AE prevalence in Western Europe and southern Gansu Province, China.

METHODS AND FINDINGS

Xiji County, Ningxia Hui Autonomous Region, borders southern Gansu. The aims of this study were to map AE prevalence across Xiji and test arvicoline habitat as a predictor. Land cover was mapped using remotely sensed (Landsat) imagery. Infection status of 3,205 individuals screened in 2002-2003 was related, using generalised additive mixed models, to covariates: gender; farming; ethnicity; dog ownership; water source; and areal cover of mountain pasture and lowland pasture. A Markov random field modelled additional spatial variation and uncertainty. Mountain pasture and lowland pasture were associated with below and above average AE prevalence, respectively.

CONCLUSIONS

Low values of the normalised difference vegetation index indicated sub-optimality of lowland pasture for grassland arvicolines. Unlike other known endemic areas, grassland arvicolines probably did not provide the principal reservoir for Echinococcus multilocularis in Xiji. This result is consistent with recent small mammal surveys reporting low arvicoline densities and high densities of hamsters, pikas and jerboas, all suitable intermediate hosts for E. multilocularis, in reforested lowland pasture. The risk of re-emergence is discussed. We recommend extending monitoring to: southern Haiyuan County, where predicted prevalence was high; southern Xiji County, where prediction uncertainty was high; and monitoring small mammal community dynamics and the infection status of dogs.

Long-term experience on surgical treatment of alveolar echinococcosis

INTRODUCTION

Alveolar echinococcosis (AE) is life-threatening and reports on surgical procedures and results are rare, but essential.

MATERIALS AND METHODS

Longitudinal surveillance and long-term follow-up of patients surgically treated for AE during the periods 1982-1999 (group A) and 2000-2006 (group B).

SETTING

University hospital within an endemic area.

RESULTS

The median (min-max) follow-up period was 141 (5-417) months. Forty-eight surgical procedures were performed in 36 patients with AE: 63% were partial resections of the liver (additional extrahepatic resection in ten of them), 17% just extrahepatic resections, 10% biliodigestive anastomosis, and 10% exploratory laparotomies. Seventy-five percent of the operations were first-time procedures, 25% done due to a relapse. Forty-two percent of the operations were estimated to be curative (R0), whereas 58% were palliative (R1, R2). All patients had additional medical treatment and periodical follow-up. Two out of 18 (11%) patients, estimated to have had curative surgery, developed a relapse 42 and 54 months later. R0-resection rates depended on the primary, neighboring, metastasis stage of AE (S1, 100%; S2, 100%; S3a, 33%; S3b, 27%; S4, 11%). During the period 2000-2006 elective radical surgery for AE was done only if a safe distance of at least 2 cm was attainable. This concept was associated with an increased R0-resection rate of 87% for group B compared to 24% for group A. Operative procedures done to control complicated courses of AE (jaundice, cholangitis, vascular compression, bacterial superinfection) have not been curative (R2) in 82% because the disease had spread into irresectable structures. Morbidity was 19%. All patients with curative resections are alive. Fifty-six percent of the patients with palliative treatment are alive as long as 14-237 months, 28% died from AE 164-338 months after diagnosis (late lethality), and 17% died due to others diseases 96-417 months after diagnosis of AE. One out of seven (14%) patients suffering from suppurative parasitic necrosis died because it was impossible to control systemic sepsis (3% hospital lethality).

CONCLUSION

Curative surgery for AE is feasible if the parasitic mass is removable entirely. The earlier the stage, the more frequent is R0 resectability. The observance of a minimal safe distance increases the rate of R0 resections. The benefit of palliative surgery is uncertain due to favorable long-term results of medical treatment alone. However, necrotic tissue is at risk of bacterial superinfection, which can cause life-threatening sepsis. Palliative surgery is an option to treat complications, which could not be managed otherwise.

Survey of public knowledge about Echinococcus multilocularis in four European countries: need for proactive information

Background

Public information about prevention of zoonoses should be based on the perceived problem by the public and should be adapted to regional circumstances. Growing fox populations have led to increasing concern about human alveolar echinococcosis, which is caused by the fox tapeworm Echinococcus multilocularis. In order to plan information campaigns, public knowledge about this zoonotic tapeworm was assessed.

Methods

By means of representative telephone interviews (N = 2041), a survey of public knowledge about the risk and the prevention of alveolar echinococcosis was carried out in the Czech Republic, France, Germany and Switzerland in 2004.

Results

For all five questions, significant country-specific differences were found. Fewer people had heard of E. multilocularis in the Czech Republic (14%) and France (18%) compared to Germany (63%) and Switzerland (70%). The same effect has been observed when only high endemic regions were considered (Czech Republic: 20%, France: 17%, Germany: 77%, Switzerland: 61%). In France 17% of people who knew the parasite felt themselves reasonably informed. In the other countries, the majority felt themselves reasonably informed (54–60%). The percentage that perceived E. multilocularis as a high risk ranged from 12% (Switzerland) to 43% (France). In some countries promising measures as deworming dogs (Czech Republic, Switzerland) were not recognized as prevention options.

Conclusion

Our results and the actual epidemiological circumstances of AE call for proactive information programs. This communication should enable the public to achieve realistic risk perception, give clear information on how people can minimize their infection risk, and prevent exaggerated reactions and anxiety.

Alveolar echinococcosis: from a deadly disease to a well-controlled infection. Relative survival and economic analysis in Switzerland over the last 35 years

BACKGROUND/AIMS

Alveolar echinococcosis (AE) is a serious liver disease. The aim of this study was to explore the long-term prognosis of AE patients, the burden of this disease in Switzerland and the cost-effectiveness of treatment.

METHODS

Relative survival analysis was undertaken using a national database with 329 patient records. 155 representative cases had sufficient details regarding treatment costs and patient outcome to estimate the financial implications and treatment costs of AE.

RESULTS

For an average 54-year-old patient diagnosed with AE in 1970 the life expectancy was estimated to be reduced by 18.2 and 21.3 years for men and women, respectively. By 2005 this was reduced to approximately 3.5 and 2.6 years, respectively. Patients undergoing radical surgery had a better outcome, whereas the older patients had a poorer prognosis than the younger patients. Costs amount to approximately Euro108,762 per patient. Assuming the improved life expectancy of AE patients is due to modern treatment the cost per disability-adjusted life years (DALY) saved is approximately Euro6,032.

CONCLUSIONS

Current treatments have substantially improved the prognosis of AE patients compared to the 1970s. The cost per DALY saved is low compared to the average national annual income. Hence, AE treatment is highly cost-effective in Switzerland.

Echinococcosis in China, a review of the epidemiology of Echinococcus spp

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly significant infectious diseases occurring worldwide and caused by metacestodes of tapeworms Echinococcus granulosus and E. multilocularis, respectively. Both human CE and AE have highest prevalence rates in western and northwestern China. Livestock is the main intermediate host of E. granulosus, and wild small mammal are the main intermediate hosts of E. multilocularis. Since they range freely in pastoral areas, prey on wild small mammals and offal of livestock after slaughter, and have close relationships with humans, domestic dogs are the most important definitive host of both Echinococcus spp. with the highest risk of transmitting CE and AE to humans. Pastoralism is the occupation with the highest risk of being infected with the both kinds of echinococcosis due to the proximity of livestock, dogs, and wildlife host species. In this review, we summarize the epidemiology of human echinococcosis, the situation of parasite transmission in animal hosts, and possible transmission patterns in China. In addition, human activities and their potential influence on the transmission of echinococcosis are also discussed.

Underreporting of human alveolar echinococcosis, Germany

We estimated the total number of human alveolar echinococcosis cases in Germany from 2003 through 2005 using the multiple source capture-recapture method. We found a 3-fold higher incidence of the disease than that shown by national surveillance data. We propose a revision of the reporting system to increase case ascertainment.

The first case of human alveolar echinococcosis in Hungary

Infection caused by Echinococcus multilocularis is a rare helminthiasis, human cases have not been diagnosed in Hungary until now. The endemic region is Central Europe; the occurrence of this infection has been reported from most of the neighbouring countries; however, E. multilocularis has been found in the red fox population in Hungary. Summarizing the recent knowledge concerning epidemiological, clinical patterns and therapeutic options, the authors describe the first Hungarian case of alveolar echinococcosis. In the presence of appropriate clinical findings, the possibility of this rare infection has to be considered in the differencial diagnosis of infiltrative hepatic lesions.

Imaging of Parasitic Diseases of the Thorax

A broad spectrum of parasitic infections frequently affects the lungs, mediastinum, and thoracic wall, manifesting with abnormal imaging findings that often make diagnosis challenging. Although most of these infections result in nonspecific abnormalities, familiarity with their imaging features and the diagnostic pathways help the radiologist to formulate an adequate differential diagnosis and to guide diagnosticians in reaching a definitive diagnosis.

Infection of red foxes with Echinococcus multilocularis in western Switzerland

In the Jura mountains, Plateau and Alps of western Switzerland important variations in the prevalence of Echinococcus multilocularis infection in red foxes were observed between geographical areas from 1990 to 1995. The Jura mountains and the Plateau had higher mean prevalence levels than the Alps with 30.6, 32.4 and 18.8%, respectively. The highest rate was recorded in the Plateau in the canton of Fribourg with a prevalence of 52.3%. The prevalence of E. multilocularis infection in foxes in the alpine canton of Valais was the lowest (7.1%). Juvenile foxes were found to be more susceptible to E. multilocularis than adults. Adult foxes were less heavily infected in summer and autumn, while the prevalence in juveniles (less than 1 year old) increased between the spring and winter, when they are more than 6 months old. The retrospective data relate to the beginning of the 1990s, since when a drastic prevalence increase of E. multilocularis infection in foxes has occurred in several regions of Europe. Nevertheless, the study is a major contribution to the epidemiological situation of E. multilocularis in central Europe, in that it contains valuable information on spatial distribution and seasonal differences in different age groups of foxes.

[Relevance of parasitological examinations for the clinical course, epidemiology and prevention of alveolar echinococcosis - experiences of more than two decades in Austria]

Alveolar echinococcosis has been known in Austria since 1854. At the beginning of the 20th century the Austrian researcher on echinococcosis, Adolf Posselt, has realized already the enormous medical relevance of serological tests for the diagnosis of alveolar echinococcosis as well as for preventive purposes. Since the beginning of the 1980ies a long-term study about the epidemiology and serodiagnosis of alveolar echinococcosis has started in the Department of Medical Parasitology of the Clinical Institute of Hygiene and Medical Microbiology of the University of Vienna. Today a highly sensitive enzyme-linked immunosorbent assay as well as a highly specific westernblot system are available for the serological diagnosis of human alveolar echinococcosis cases, for the serological monitoring of the disease as well as for seroepidemiological and preventive medical studies. In addition, molecular biological tools for the detection of E. multilocularis (as well as E. granulosus strain) specific DNA in surgical resected and bioptic materials complete our diagnostic spectrum of methods.

Laparoscopic resection of a primary hydatid cyst of the adrenal gland: a case report

Background

Echinococcosis rates vary in different parts of the world. Italy is regarded as a middle to high risk country with over 1,000 cases requiring surgery each year. Liver (45–75%) and lung (10–50%) are the most frequent locations of this parasitosis.

Case presentation

The authors report a clinical case of a 62 year old woman, admitted to hospital with left flank pain. Plain radiographs of the abdomen, ultrasound, CT and MRI scans were performed and the presence of a 3-cm lesion of the left adrenal gland was demonstrated. A diagnosis of hydatid cyst was made. The patient underwent transabdominal laparoscopic left adrenalectomy. Histopathological examination confirmed the presence of a hydatid cyst in the left adrenal gland.

Conclusion

A hydatid cyst was correctly diagnosed on the basis of radiologic findings. The uncomplicated cyst was successfully resected using a laparoscopic approach. The pathological features of this case are presented in this paper.

Human alveolar echinococcosis after fox population increase, Switzerland

An increase in fox population has led to an increase in incidence of human alveolar echinococcosis.

We analyzed databases spanning 50 years, which included retrospective alveolar echinococcosis (AE) case-finding studies and databases of the 3 major centers for treatment of AE in Switzerland. A total of 494 cases were recorded. Annual incidence of AE per 100,000 population increased from 0.12– 0.15 during 1956–1992 and a mean of 0.10 during 1993–2000 to a mean of 0.26 during 2001–2005. Because the clinical stage of the disease did not change between observation periods, this increase cannot be explained by improved diagnosis. Swiss hunting statistics suggested that the fox population increased 4-fold from 1980 through 1995 and has persisted at these higher levels. Because the period between infection and development of clinical disease is long, the increase in the fox population and high Echinococcus multilocularis prevalence rates in foxes in rural and urban areas may have resulted in an emerging epidemic of AE 10–15 years later.

Assessment of use of microsatellite polymorphism analysis for improving spatial distribution tracking of echinococcus multilocularis

Alveolar echinococcosis (AE)--caused by the cestode Echinococcus multilocularis--is a severe zoonotic disease found in temperate and arctic regions of the northern hemisphere. Even though the transmission patterns observed in different geographical areas are heterogeneous, the nuclear and mitochondrial targets usually used for the genotyping of E. multilocularis have shown only a marked genetic homogeneity in this species. We used microsatellite sequences, because of their high typing resolution, to explore the genetic diversity of E. multilocularis. Four microsatellite targets (EmsJ, EmsK, and EmsB, which were designed in our laboratory, and NAK1, selected from the literature) were tested on a panel of 76 E. multilocularis samples (larval and adult stages) obtained from Alaska, Canada, Europe, and Asia. Genetic diversity for each target was assessed by size polymorphism analysis. With the EmsJ and EmsK targets, two alleles were found for each locus, yielding two and three genotypes, respectively, discriminating European isolates from the other groups. With NAK1, five alleles were found, yielding seven genotypes, including those specific to Tibetan and Alaskan isolates. The EmsB target, a tandem repeated multilocus microsatellite, found 17 alleles showing a complex pattern. Hierarchical clustering analyses were performed with the EmsB findings, and 29 genotypes were identified. Due to its higher genetic polymorphism, EmsB exhibited a higher discriminatory power than the other targets. The complex EmsB pattern was able to discriminate isolates on a regional and sectoral level, while avoiding overdistinction. EmsB will be used to assess the putative emergence of E. multilocularis in Europe.

Emerging zoonoses and vector-borne infections affecting humans in Europe

The purpose of this study was to assess and describe the current spectrum of emerging zoonoses between 2000 and 2006 in European countries. A computerized search of the Medline database from January 1966 to August 2006 for all zoonotic agents in European countries was performed using specific criteria for emergence. Fifteen pathogens were identified as emerging in Europe from 2000 to August 2006: Rickettsiae spp., Anaplasma phagocytophilum, Borrelia burgdorferi, Bartonella spp., Francisella tularensis, Crimean Congo Haemorrhagic Fever Virus, Hantavirus, Toscana virus, Tick-borne encephalitis virus group, West Nile virus, Sindbis virus, Highly Pathogenic Avian influenza, variant Creutzfeldt-Jakob disease, Trichinella spp., and Echinococus multilocularis. Main risk factors included climatic variations, certain human activities as well as movements of animals, people or goods. Multi-disciplinary preventive strategies addressing these pathogens are of public health importance. Uniform harmonized case definitions should be introduced throughout Europe as true prevalence and incidence estimates are otherwise impossible.

Human alveolar echinococcosis in Slovenia

Between January 2001 and December 2005, 1263 patients suspected of having echinococcosis were screened serologically by indirect haemagglutination assay (IHA). IHA-positive patient sera were then retested by western blot for confirmation and differentiation between Echinococcus granulosus and Echinococcus multilocularis infection. Of 43 sera confirmed as Echinococcus-positive, nine appeared to be specific for alveolar echinococcosis (AE) caused by E. multilocularis. AE-positive serological results corresponded to the clinical and/or imaging findings concerning the patients' liver cysts. The detected incidence of AE was 0.45/10(5) inhabitants, which suggests that clinicians and health authorities in Slovenia should give greater attention to AE in the future.

Spatial spreading of Echinococcus multilocularis in Red foxes (Vulpes vulpes) across nation borders in Western Europe

The occurrence of the fox tapeworm Echinococcus multilocularis in Red foxes was studied in Belgium and a neighbouring region in The Netherlands. A total number of 1202 foxes were analysed (1018 in Belgium and 184 in The Netherlands) of which 179 were infected with E. multilocularis (164 in Belgium and 15 in The Netherlands). Further, the spatial distribution of infection among sampled foxes was analysed with an ellipsoidal gradient, demonstrating a decreasing prevalence in northwestern direction. Using this gradient, we showed that the spatial patterns of infection in Belgium and the neighbouring region in The Netherlands correspond, indicating a continuous distribution of E. multilocularis across the nation borders. Part of the Belgian data allowed investigating temporal changes in the spatial distribution of E. multilocularis. This revealed a northwestern spread of E. multilocularis.

Alveolar echinococcosis of the liver in a Tokyo resident with an unknown route of infection: report of a case

We report the case of a 45-year-old Tokyo man who developed alveolar echinococcosis of the liver, which is an extremely rare disorder in Japan, except for Hokkaido, Japan's northernmost island. The findings of multiple clustered cysts on computed tomography were unlike those of any hepatic tumors we had previously encountered. T2-weighted magnetic resonance imaging revealed the characteristic findings of small cysts with a very high signal intensity. The tumors were successfully removed by a hepatic resection. The patient lives in Tokyo, but has visited Hokkaido many times. The exact route of infection in this patient remains unclear. Sliced raw venison, which he reported eating on every visit to Sapporo in Hokkaido, represented the only potential route of infection we could identify. This meat may have somehow become contaminated with embryonated eggs. Nowadays, even city inhabitants are at risk of developing rare diseases due to the rapid development of transportation systems.

Pasture types and Echinococcus multilocularis, Tibetan communities

Our study showed that open pastures had more small mammal burrows than fenced pastures in Tibetan pastoralist communities in 2003. This characteristic was linked to a higher prevalence of Echinococcus multilocularis in dogs and indicates that pasture type may affect E. multilocularis transmission.

Parasitic diseases of the respiratory tract

PURPOSE OF REVIEW

The human pulmonary system can be affected by a variety of parasites. This review focuses on the most common parasitic infestations involving the lung, except for protozoon disease.

RECENT FINDINGS

In many parasitic lung conditions, the clinical manifestations and the imaging findings are non-specific and can make diagnosis challenging. Hydatid disease and paragonimiasis involve the lung directly. Chronic schistosomiasis can lead to pulmonary hypertension. Strongyloides stercoralis infestation is capable of transforming into a fulminant fatal disease. In many types of nematode infestations, the pulmonary phase can cause acute eosinophilic pneumonia. Chest radiographs of patients with paragonimiasis and dirofilariasis can cause diagnostic confusion. Cases of tropical pulmonary eosinophilia typically present with refractory bronchial asthma. Most of these diseases are initially diagnosed by detecting eggs or larvae in stool, sputum, pleural fluid or tissue, and are confirmed by serologic testing. Cystic hydatid disease generally requires surgical treatment, whereas almost all other parasitic lung conditions can be treated medically.

SUMMARY

Although most parasites that affect the lung are endemic to tropical and subtropical regions, immigration and travel practices have resulted in transfer of these diseases to other areas. It is important for physicians to know the epidemiologic characteristics, clinical presentations, and treatments of choice for these conditions.

Emergence/re-emergence of Echinococcus spp.--a global update

This review provides an update of the biological aspects of the genus Echinococcus and focuses on newly recognized endemic areas. Infection with the intermediate cystic stage of all species of Echinococcus causes disease and incapacity in animals and humans, and in the most serious cases, death of the host. Transmission of Echinococcus to new continents has occurred during European colonisation and the parasite has often taken advantage of Echinococcus-naive wildlife populations in these new environments, incorporating them into its transmission pattern. Echinococcus granulosus consists of a complex of 10 strains. Host specificities of these strains have important implications for transmission and control. As a result of human behaviour and/or political instability in a number of countries Echinococcus is re-emerging as an important public health issue. The importance of wildlife reservoirs in perpetuating transmission and as a source of infection for domestic animals and humans is addressed. The review also refers to the transmission pattern of a recently described new species, Echinococcus shiquicus, from China.

Echinococcosis in Tibetan populations, western Sichuan Province, China

This area has the highest prevalences of both forms of this disease in the world.

We screened 3,199 people from Shiqu County, Sichuan Province, China, for abdominal echinococcosis (hydatid disease) by portable ultrasound combined with specific serodiagnostic tests. Both cystic echinococcosis (CE) (Echinococcus granulosus infection) and alveolar echinococcosis (AE) (E. multilocularis) were co-endemic in this area at the highest village prevalence values recorded anywhere in the world: 12.9% were infected with one or the other form (6.8% CE and 6.2% AE). Prevalences of both CE and AE were significantly higher in female than male patients and increased with the age of the person screened. Pastoral herdsmen were at highest risk for infection (prevalence 19.0%). Prevalence of CE varied in 5 townships from 0% to 12.1%, whereas AE prevalence ranged from 0% to 14.3%. Risk factors associated with both infections included the number of owned dogs, frequency of contact with dogs, and sources of drinking water.

Implications of increased susceptibility to predation for managing the sylvatic cycle of Echinococcus multilocularis

The ability to increase the chances that infectious prey are taken by predators is an observed feature of many parasites that rely on one or more predator-prey relationships to complete their life-cycle. In the sylvatic life-cycle of Echinococcus multilocularis - the causative agent of human alveolar echinococcosis-- foxes are the final host, with voles acting as intermediate hosts. Here we review the evidence that E. multilocularis causes increased susceptibility to predation and present a general mathematical model for the sylvatic life-cycle. The ability to increase susceptibility to predation in the intermediate host reduces the sensitivity of the parasite population to adverse conditions. For example, there is no critical density of foxes below which the parasite is expected to die out, even if the effect of the parasite on infected prey is very small. We suggest that increased susceptibility to predation is a plausible explanation for the observed resilience of E. multilocularis during and following field trials of praziquantel baiting.

Imaging aspects and non-surgical interventional treatment in human alveolar echinococcosis

Alveolar echinococcosis (AE) of the liver caused by the metacestode of the fox tapeworm Echinococcus multilocularis is characterized by a multivesicular structure surrounded by an extensive fibro-inflammatory host reaction. The lesions behave like a slow-growing liver cancer, without sharp limits between the parasitic tissue and the liver parenchyma. Invasion of biliary and vascular walls is another hallmark of this severe disease. Moreover, the poor vascularization of the parasitic mass often leads to necrosis in the central part of the lesion. This explains why liver abscess due to superimposed bacterial infection of the necrotic area may occur in this disease. Currently, a range of imaging techniques can be used at the different stages of management of AE. For diagnosis, ultrasonography remains the first line examination. For a more accurate disease evaluation, aiming to guide the surgical strategy, computerized tomography, Magnetic Resonance (MR) imaging, including cholangio-MR imaging are of importance, providing useful complementary information. More recently, Positive-Emission Tomography using [18F] fluoro-deoxyglucose has been developed for the follow-up of inoperable AE patients under long-term benzimidazoles therapy. This approach seems very promising to assess inflammatory activity and thereby to indirectly depict parasitic activity. Non-surgical interventional procedures, mainly percutaneous biliary and/or centro-parasitic abscesses drainages, are currently a major aspect in the care of incurable AE patients and have largely contributed to the improvement of survival in this situation during the past 20 years. They may also be used as a bridge before a curative surgical procedure in symptomatic patients presenting a life-threatening bacterial and/or fungal infection. It is also very useful in inoperable patients to overcome similar infectious episodes.

Progress in diagnosis, treatment and elimination of echinococcosis and cysticercosis

Here I review the current status of geographical occurrence and public health significance of echinococcosis (Echinococcus spp. infections) and cysticercosis (Taenia solium infection) with special emphasis on the remarkable technologic progress achieved in recent decades that has led to greater understanding of the biology and epidemiology of these cestode infections. The greatest remaining challenges are to apply this knowledge and technology to improved medical management and prevention of these infections.

Survival strategy of Echinococcus multilocularis in the human host

As exemplified by "aborted" calcified liver lesions commonly found in patients from endemic areas, Echinococcus multilocularis metacestodes develop only in a minority of individuals exposed to infection with the papasite. Clinical research has disclosed some aspects of the survival strategy of E. multilocularis in human hosts. Clinical observations in liver transplantation and AIDS suggest that suppression of cellular/Th1-related immunity increases disease severity. Most of the studies have stressed a role for CD8+ T cells and for Interleukin-10 in the development of tolerance. A spontaneous secretion of IL-10 by the PBMC seems to be the immunological hallmark of patients with progressive forms of alveolar echinococcosis (AE). IL-10-induced inhibition of effector macrophages, but also of antigen-presenting dendritic cells, may be operating and allowing parasite growth and survival. The genetic correlates of susceptibility to infection with E. multilocularis are clearer in humans than in the mouse model. A significant link between MHC polymorphism and clinical presentation of AE has been shown, and the spontaneous secretion of IL-10 in patients with a progressive AE is higher in patients with the HLA DR3+, DQ2+ haplotype. Clustering of cases in certain families, in communities otherwise exposed to similar risk factors, also points to immuno-genetic predisposition factors that may allow the larva to escape host immunity more easily. The first stage of larval development may be crucial in producing "danger signals" stimulating the initial production of cytokines. Therapeutic use of Interferon alpha is an attempt to foil the survival strategy of E. multilocularis.

WHO classification of alveolar echinococcosis: principles and application

Alveolar echinococcosis is caused by the larval stage of the fox tapeworm (Echinococcus multilocularis) and is frequently diagnosed as a space occupying lesion in the liver. The growth pattern resembles that of a malignant tumor with infiltration throughout the liver, spreading into neighbouring organs and metastases formation in distant organs. Thus, one of the prevailing differential diagnoses is liver cancer. Guided by the Tumor-Node-Metastasis (TNM) system of liver cancer, the European Network for Concerted Surveillance of Alveolar Echinococcosis and the WHO Informal Working Group on Echinococcosis proposed a clinical classification for alveolar echinococcosis. It was designated as PNM system (P = parasitic mass in the liver, N = involvement of neighbouring organs, and M = metastasis). As for TNM in oncology, single PNM categories were combined into four stages, I to IV. The system was developed by a retrospective analysis of 97 patients' records from two treatment centers (Besançon/France and Ulm/Germany). Recently, this WHO classification was applied to 222 patients in 4 clinical centers around the world (Besançon/France, n = 26; Urumqi/China, n = 46; Sapporo/Japan, n = 58; and Ulm/Germany, n = 92). All patients could be classified who had been diagnosed in the period from January 1998 to June 2005. The stage grouping indicated center differences, but appeared to segregate patients according to various treatment regimens. The WHO classification not only serves as a tool for the international standardization of disease manifestation but also aids to evaluate the outcome of a chosen diagnostic and treatment procedure in different treatment centers in Europe and Asia.

The present situation of echinococcosis in Europe

The taxonomy of Echinococcus is presently undergoing major changes, the paraphyletic Echinococcus granulosus being split into several distinct species. In this review, an attempt is made to assess the present epidemiological situation in Europe separately for each species (Echinococcus multilocularis, Echinococcus granulosus sensu stricto, Echinococcus equinus, Echinococcus ortleppi, and Echinococcus sp.). For E. multilocularis, an increasing density of infected host animals is apparent in central Europe, and, possibly, a range increase has occurred. Prevalence rates in foxes have risen in many agriculturally dominated landscapes of France, The Netherlands, Germany, Austria, Slovakia and Poland, but the lifecycle is now also established in many urban areas, where red foxes occur with high population densities. E. granulosus s. s. (the former 'sheep strain') is still frequent and a public health problem in many parts of the Mediterranean region and re-emergence after failed control campaigns is observed or suspected in Bulgaria and Wales. No recent data on the cattle-transmitted E. ortleppi and the horse-transmitted E. equinus are available, but their relevance for human health seems to be minor. The same may apply to the 'pig strain' and the newly described 'European cervid strain', which both belong to a cluster of genotypes whose taxonomy is not yet resolved (Echinococcus sp.).

Brain metastasis of alveolar echinococcosis in a hyperendemic focus of Echinococcus multilocularis infection

An unusual female case, with alveolar echinococcosis (AE) disseminated from the primary hepatic lesion to the brain by metastasis formation, was retrospectively identified during a community survey in Ningxia Hui Autonomous Region, northwest China in 2003. Among possible metastases of hepatic AE, locations to the brain are rare and usually fatal; and they have especially been assigned to concomitant immune suppression. An enhancing role of pregnancy, which may be suspected in this case, the favourable outcome after surgery and chemotherapy, and also a mental disability in a child following long-term intrauterine exposure to mebendazole, make the report particularly unique.

[A probable case of alveolar echinococcosis in Normandy, France]

Echinococcus multilocularis induced liver infection was diagnosed in a Moroccan patient. Diagnosis was based on CT scan results and Western Blot test. Contamination probably occurred in France, in the Cherbourg area where the patient travelled frequently and ate wild berries. This case and other recently reported cases outside the usual endemic areas (Besançon and the Massif Central) suggest that the Echinococcus multilocularis epidemic has moved towards the west of France. French gastroenterologists should be aware of this parasitic disease.

Evaluation of treatment and long-term follow-up in patients with hepatic alveolar echinococcosis

BACKGROUND

Alveolar echinococcosis is a rare disorder, which makes a comparison of different treatment modalities within a clinical trial difficult to perform. Data prospectively recorded over a period of 25 years were used to evaluate three therapeutic strategies: benzimidazole therapy alone, complete 'curative' resection followed by 2 years of adjuvant benzimidazole treatment, and partial debulking resection followed by continuous administration of a benzimidazole.

METHODS

Details of 113 patients with hepatic alveolar echinococcosis treated between 1976 and 2003 were analysed. Kaplan-Meier survival curves were constructed and, using a Cox regression model, patient age, year of initial treatment and PNM stage were entered as co-variates in the analysis.

RESULTS

Kaplan-Meier overall survival curves stratified for treatment strategy indicated an improved long-term survival in patients undergoing the debulking procedure (P = 0.061) or curative resection (P = 0.002) compared with benzimidazole therapy alone. However, when PNM stage, patient age and year of initial treatment were introduced into the analysis, there was a trend for survival advantage only with curative resection (P = 0.07 versus benzimidazole alone). Debulking resulted in a higher rate of progression of hepatic echinococcosis than curative surgery (P = 0.008). The incidence of parasite-related complications was similar for debulking resection and benzimidazole therapy alone (P = 0.706).

CONCLUSION

Debulking hepatic resections do not appear to offer any advantage in the treatment of patients with alveolar echinococcosis.

Neuroparasitic infections: cestodes, trematodes, and protozoans

Parasitic infection of the nervous system can produce a variety of symptoms and signs. Because symptoms of infection are often mild or nonspecific, diagnosis can be difficult. Familiarity with basic epidemiological characteristics and distinguishing radiographic findings can increase the likelihood of detection and proper treatment of parasitic infection of the nervous system. This article discusses the clinical presentation, diagnosis, and treatment for some of the more common infections of the nervous system caused by cestodes, trematodes and protozoans: Echinococcus spp., Spirometra spp. (sparganosis), Paragonimus spp., Schistosoma spp., Trypanosoma spp., Naegleria fowlerii, Acanthamoeba histolytica, and Balamuthia mandrillaris.

Detection of Echinococcus multilocularis in wild boars in France using PCR techniques against larval form

Recently, new data have been collected on the distribution and ecology of Echinococcus multilocularis in European countries. Different ungulates species such as pig, goat, sheep, cattle and horse are known to host incomplete development of larval E. multilocularis. We report a case of E. multilocularis portage in two wild boars from a high endemic area in France (Department of Jura). Histological examination was performed and the DNA was isolated from hepatic lesions then amplified by using three PCR methods in two distinct institutes. Molecular characterisation of PCR products revealed 99% nucleotide sequence homology with the specific sequence of the U1 sn RNA gene of E. multilocularis, 99 and 99.9% nucleotide sequence homology with the specific sequence of the cytochrome oxydase gene of Echinococcus genus and 99.9% nucleotide sequence homology with a genomic DNA sequence of Echinococcus genus for the first and the second wild boar, respectively.

Transmission dynamics of Echinococcus multilocularis; its reproduction number, persistence in an area of low rodent prevalence, and effectiveness of control

On the basis of high prevalences of Echinococcus multilocularis in the growing fox populations in Central Europe, its total biomass may have increased significantly in the past 20 years. E. multilocularis is now also found in areas outside the known endemic area in Central Europe. Therefore, E. multilocularis, the causative agent of a serious parasitic zoonosis, might be of major concern for public health and a challenge to control. Some experimental field trials to control E. multilocularis using an anti-worm drug reduced parasite burden in a contaminated region during the control campaign, but failed to eradicate the parasite completely. It was our aim to develop a mathematical model describing the biomass of egg, larval, and adult worm stages of the E. multilocularis life-cycle, and simulate a hypothetical control campaign. Additionally, we derived the reproduction number of this parasite and explored conditions for the persistence of the parasite's life-cycle. Our model shows that while control campaigns rapidly reduce the worm burden in the definitive host, and consequently eggs in the environment, the pool of larvae in the intermediate host remains large. The parasite's life-cycle persists in a region where prevalence in the intermediate host is low (∼1%). Therefore, we conclude that the parasite is likely to re-emerge if control is discontinued on the basis of reduced worm population. Continued treatment of the definitive host is required to eradicate the larval stage of the parasite from the intermediate host population.

Risk factors for alveolar echinococcosis in humans

A case-control study of alveolar echinococcosis cases in Germany identifies several risk factors for the disease.

We conducted a case-control study to investigate risk factors for acquiring autochthonous alveolar echinococcosis in Germany. Forty cases and 120 controls matched by age and residence were interviewed. Patients were more likely than controls to have owned dogs that killed game (odds ratio [OR] = 18.0), lived in a farmhouse (OR = 6.4), owned dogs that roamed outdoors unattended (OR = 6.1), collected wood (OR = 4.7), been farmers (OR = 4.7), chewed grass (OR = 4.4), lived in a dwelling close to fields (OR = 3.0), gone into forests for vocational reasons (OR = 2.8), grown leaf or root vegetables (OR = 2.5), owned cats that roamed outdoors unattended (OR = 2.3), and eaten unwashed strawberries (OR = 2.2). Sixty-five percent of cases were attributable to farming. Measures that prevent accidental swallowing of possibly contaminated material during farming or adequate deworming of pet animals might reduce the risk for alveolar echinococcosis.