Echinococcus granulosus sensu lato genotypes infecting humans--review of current knowledge

Global phylogeography and genetic diversity of the zoonotic tapeworm Echinococcus granulosus sensu stricto genotype G1

Echinococcus granulosus sensu stricto (s.s.) is the major cause of human cystic echinococcosis worldwide and is listed among the most severe parasitic diseases of humans. To date, numerous studies have investigated the genetic diversity and population structure of E. granulosus s.s. in various geographic regions. However, there has been no global study. Recently, using mitochondrial DNA, it was shown that E. granulosus s.s. G1 and G3 are distinct genotypes, but a larger dataset is required to confirm the distinction of these genotypes. The objectives of this study were to: (i) investigate the distinction of genotypes G1 and G3 using a large global dataset; and (ii) analyse the genetic diversity and phylogeography of genotype G1 on a global scale using near-complete mitogenome sequences. For this study, 222 globally distributed E. granulosus s.s. samples were used, of which 212 belonged to genotype G1 and 10 to G3. Using a total sequence length of 11,682 bp, we inferred phylogenetic networks for three datasets: E. granulosus s.s. (n = 222), G1 (n = 212) and human G1 samples (n = 41). In addition, the Bayesian phylogenetic and phylogeographic analyses were performed. The latter yielded several strongly supported diffusion routes of genotype G1 originating from Turkey, Tunisia and Argentina. We conclude that: (i) using a considerably larger dataset than employed previously, E. granulosus s.s. G1 and G3 are indeed distinct mitochondrial genotypes; (ii) the genetic diversity of E. granulosus s.s. G1 is high globally, with lower values in South America; and (iii) the complex phylogeographic patterns emerging from the phylogenetic and geographic analyses suggest that the current distribution of genotype G1 has been shaped by intensive animal trade.

First description of Echinococcus ortleppi and cystic echinococcosis infection status in Chile

Cystic echinococcosis (CE), a parasitic disease caused by the cestode Echinococcus granulosus sensu lato (s.l.), is a worldwide zoonotic infection. Although endemic in Chile, information on the molecular characteristics of CE in livestock remains scarce. Therefore we aimed to describe the status of infection with E. granulosus s.l. in cattle from central Chile and also to contribute to the study of the molecular epidemiology of this parasite. According to our results, the prevalence of CE is 18.84% in cattle, similar to previous reports from Chile, suggesting that the prevalence in Santiago Metropolitan area has not changed in the last 30 years. Most of the cysts were found only in lungs (51%), followed by concurrent infection in liver and lungs (30%), and only liver (19%). Molecular characterization of the genetic diversity and population structure of E. granulosus s.l. from cattle in central Chile was performed using a section of the cytochrome c oxidase subunit 1 (cox1) mitochondrial gene. E. granulosus sensu stricto (s.s.) (G1-G3 genotypes) was confirmed by RFLP-PCR to be the dominant species affecting cattle (284 samples/290 samples); we also report for the first time in Chile the presence of E. ortleppi (G5 genotype) (2 samples/61 samples). The Chilean E. granulosus s.s. parsimony network displayed 1 main haplotype. Additional studies using isolates from many locations across Chile and different intermediate hosts will provide more data on the molecular structure of E. granulosus s.s. within this region. Likewise, investigations of the importance of E. ortleppi in human infection in Chile deserve future attention.

Human cystic echinococcosis in Hungary (2000-2014): a retrospective case series analysis from a single-center study

PURPOSE

Cystic echinococcosis (CE) is a parasitic disease caused by the tapeworm Echinococcus granulosus sensu lato. Although in Hungary the disease is listed among reportable infections, inadequacies in the reporting practice of CE by clinicians and pathologists have resulted in underscoring of this disease. The aim of this study was to describe the epidemiological and clinical characteristics of CE in Hungary using a datasource other than the official records that are based mainly on serological data.

METHODS AND RESULTS

This retrospective case series study included a total of 45 CE patients confirmed by histopathology in a single Hungarian center between 2000 and 2014.

CONCLUSION

 Although CE is the most prevalent reportable endemic helminthosis in Hungary, to date this is the first study on the clinical epidemiology of the disease in this country.

Cerebral cystic echinococcosis in Mongolian children caused by Echinococcus canadensis

Recent molecular re-evaluation of Echinococcus granulosus, which causes cystic echinococcosis (CE), has revealed that it is not a single species, but instead consists of 5 cryptic species. Among them, E. granulosus (dog-sheep strain) is predominant (75%) followed by Echinococcus canadensis (22%). The major affected organs, in humans, are the liver (88%) and lungs (11%). Primary cerebral CE comprises less than 1% of all cases. As cerebral CE cases are rare, there are few reports with molecular confirmation of the causative species. This study reports mitochondrial gene analysis from 4 Mongolian pediatric cerebral CE cases. Molecular confirmation was obtained for 3 of the 4 cases, with all 3 cases determined to be due to E. canadensis (G6/G7) infection. None of the cases had other organ involvement. This is only the third report on the molecular identification of the Echinococcus species responsible for cerebral CE, and only the second report of E. canadensis (G6/G7) being the causative agent of cerebral CE.

Echinococcus ortleppi, the cattle strain in a crested porcupine (Hystrix cristata): A new host record

Echinococcus granulosus sensu lato, a dog tapeworm is a species complex causing cystic echinococcosis or hydatid disease in a great variety of mammalian intermediate hosts, including humans. This complex comprises five species including Echinococcus ortleppi (G5 genotype or cattle strain). In the present paper, we report the first case of infection with the larval stage of latter cestode in a captive crested porcupine (Hystrix cristata), molecularly confirmed by PCR and sequencing of the cox1 and nad1 genes. The food contaminated with the parasite's eggs is the most likely source of the infection. Our data broaden the knowledge on the host range and geographical distribution of this rarely reported species of Echinococcus in Europe.

Prevalence and genotyping of Echinococcus granulosus in sheep in Narok County, Kenya

Cystic echinococcosis (CE) is a zoonotic disease caused by the larval stage of Echinococcus granulosus species (sensu lato, s.l.). In East Africa, several species/strains occur in livestock, wildlife, and humans, but there is limited information on frequencies of infection by different genotypes in the various mammalian hosts. We have obtained data on E. granulosus infection prevalence in sheep sampled from abattoirs in Narok County, southern Kenya. We inspected carcasses for the presence of hydatid cysts in 180 sheep randomly selected in five sub-locations. The overall prevalence was 16.0% (144/900 animals), with the majority of cysts (50.7%) found in the liver, followed by the lungs (36.8%), while infections involving the liver and lungs were detected in 12.5% of the sheep. PCR-RFLP genotyping of the mitochondrial nad-1 gene in all the 343 cysts identified E. granulosus G1-G3 (sensu stricto, s.s.) as the only genotype. The majority of the cysts (62.1%) were fertile, and 35.2% were sterile, while 2.7% were calcified. Considering cyst fertility, 73.02% of lung cysts were fertile compared to 53.4% in liver cysts. Our data extends previous CE studies in livestock and indicates a high level of CE infection of sheep in Narok, with a predominance of E. granulosus s.s., which is highly pathogenic and commonly infects humans. Given the high fertility rates observed in the cysts, there is an urgent need to determine whether there is a significant incidence of human infection in Narok, and initiate "One Health" control measures.

Antigen B from Echinococcus granulosus enters mammalian cells by endocytic pathways

Background

Cystic hydatid disease is a zoonosis caused by the larval stage (hydatid) of Echinococcus granulosus (Cestoda, Taeniidae). The hydatid develops in the viscera of intermediate host as a unilocular structure filled by the hydatid fluid, which contains parasitic excretory/secretory products. The lipoprotein Antigen B (AgB) is the major component of E. granulosus metacestode hydatid fluid. Functionally, AgB has been implicated in immunomodulation and lipid transport. However, the mechanisms underlying AgB functions are not completely known.

Methodology/Principal findings

In this study, we investigated AgB interactions with different mammalian cell types and the pathways involved in its internalization. AgB uptake was observed in four different cell lines, NIH-3T3, A549, J774 and RH. Inhibition of caveolae/raft-mediated endocytosis causes about 50 and 69% decrease in AgB internalization by RH and A549 cells, respectively. Interestingly, AgB colocalized with the raft endocytic marker, but also showed a partial colocalization with the clathrin endocytic marker. Finally, AgB colocalized with an endolysosomal tracker, providing evidence for a possible AgB destination after endocytosis.

Conclusions/Significance

The results indicate that caveolae/raft-mediated endocytosis is the main route to AgB internalization, and that a clathrin-mediated entry may also occur at a lower frequency. A possible fate for AgB after endocytosis seems to be the endolysosomal system. Cellular internalization and further access to subcellular compartments could be a requirement for AgB functions as a lipid carrier and/or immunomodulatory molecule, contributing to create a more permissive microenvironment to metacestode development and survival.

Antigen B (AgB) is an oligomeric lipoprotein highly abundant in Echinococcus granulosus hydatid fluid. AgB has already been characterized as an immunomodulatory protein, capable of inducing a permissive immune response to parasite development. Also, an important role in lipid acquisition is attributed to AgB, because it has been found associated to different classes of host lipids. However, the mechanisms of interaction employed by AgB to perform its functions remain undetermined. In this study, we demonstrate that mammalian cells are able to internalize E. granulosus AgB in culture and found that specific mechanisms of endocytosis are involved. Our results extend the understanding of AgB biological role indicating cellular internalization as a mechanism of interaction, which in turn, may represent a target to intervention.

Cystic echinococcosis in a domestic cat (Felis catus) in Italy

Echinococcus granulosus sensu lato is a zoonotic agent with a life cycle consisting of definitive hosts (dogs and wild carnivores), and intermediate hosts (usually ungulates). Other animals and humans may accidentally ingest eggs and contract cystic echinococcosis, acting as aberrant hosts. A 3-year-old neutered female cat was brought to a veterinary practice in Sassari (Italy) with abdominal distension. Ultrasound showed multiple intraperitoneal vesicles, which on laparotomy were found to be metacestodes of E. granulosus. Videos of the extraction of cysts are provided. Phylogenetic analysis based on a fragment of the cytochrome oxidase subunit 1 (cox1) mitochondrial gene identified the isolate as E. granulosussensu stricto genotype G1, the most common genotype circulating in Europe and the Mediterranean basin. This is the first case report of cystic echinococcosis in domestic cats from Italy.

Gene-based molecular analysis of COX1 in Echinococcus granulosus cysts isolated from naturally infected livestock in Riyadh, Saudi Arabia

The diversity and importance of Echinococcus species in domesticated animals in Saudi Arabia are poorly understood. In this study, 108 singular (hydatid) cysts were collected from goats (n = 25), sheep (n = 56) and camels (n = 27). DNA was extracted from the protoscoleces of individual fertile cysts and used for polymerase chain reaction (PCR) amplification of mitochondrial subunit 1 of the cytochrome c oxidase 1 (cox1) gene. Amplicon sequencing results revealed the presence of Echinococcus granulosus sensustricto (s.s.) (genotypes G1–G3) in 16 of the17 sheep cysts and 2 of the 27 camel cysts.of these samples, 18 (2 camel and 16 sheep) were divided into genotypes G1, G2, and G3.

Genetic diversity and phylogeography of the elusive, but epidemiologically important Echinococcus granulosus sensu stricto genotype G3

Cystic echinococcosis (CE) is a severe parasitic disease caused by the species complex Echinococcus granulosus sensu lato. Human infections are most commonly associated with E. granulosus sensu stricto (s.s.), comprising genotypes G1 and G3. The objective of the current study was to provide first insight into the genetic diversity and phylogeography of genotype G3. Despite the epidemiological importance of the genotype, it has remained poorly explored due to the ambiguity in the definition of the genotype. However, it was recently demonstrated that long sequences of mitochondrial DNA (mtDNA) provide a reliable method to discriminate G1 and G3 from each other. Therefore, we sequenced near-complete mtDNA of 39 G3 samples, covering most of the known distribution range and host spectra of the genotype. The phylogenetic network revealed high genetic variation within E. granulosus s.s. G3 and while G3 is significantly less prevalent worldwide than G1, the genetic diversity of both of the genotypes is equally high. We also present the results of the Bayesian phylogeographic analysis, which yielded several well-supported diffusion routes of genotype G3 originating from Turkey and Iran, suggesting the Middle East as the origin of the genotype.

First detection of Echinococcus granulosus sensu stricto (G1) in dogs in central Sudan

Eighty-four stray dogs shot as a part of a governmental rabies control program in two neighboring towns of central Sudan were examined for the presence of Echinococcus spp. and other intestinal helminths. Echinococcus worms were identified to species level by PCR and gene sequencing. For comparative reasons, rectal content of the necropsied dogs was examined for helminth eggs and subjected to copro-PCR for Echinococcus. At necropsy, 51.2% (43/84) of the dogs harbored Echinococcus canadensis (G6/7) worms with worm burdens ranging from 22,000 to 80,000. Dipylidiun caninum was found in 53.6% of the dogs. At coproscopy, taeniid eggs were found in 37 of the 43 dogs which were positive for Echinococcus at necropsy, but none in the 41 necropsy-negative dogs. In addition, 58% of the rectal samples contained eggs of Toxocara spp., 34.5% eggs of Trichuris spp. (34.5%), and 26% eggs of Ancylostoma caninum. Copro-PCR gave positive results for E. canadensis with 97.5% (39/40) of nonhibiting samples from the necropsy positive dogs; the one remaining dog tested positive for E. granulosus sensu stricto (G1), whose partial cox1 and nad1 sequences showed a 100% identity with various reference sequences of the G1 genotype. 100% of 38 non-inhibited samples taken from the necropsy-negative dogs were also negative in copro-PCR. This is the first study which combines prevalence and genetic identification of Echinococcus spp. in dogs of Sudan. Together with a recent report from cattle, it confirms the autochthonous presence, at low level, of E. granulosus sensu stricto in Central Sudan.

Molecular characterization of Echinococcus species in dogs from four regions of Kenya

Cystic echinococcosis is endemic both in livestock and humans in many parts of Kenya. However, very little data exists on Echinococcus infections in dogs, and therefore their role in maintaining the transmission cycles and environmental contamination with eggs of Echinococcus species is unknown. The study aimed to establish the prevalence and distribution of Echinococcus granulosus sensu lato causing infection in dogs in Kenya. A total of 1621 dog faecal samples were collected from the environment in four different regions and examined microscopically for the presence of taeniid eggs. Up to 20 individual taeniid eggs per faecal sample were picked, lysed and genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing of the NADH dehydrogenase subunit 1 (nad1) gene. Eleven percent (178/1621) of faecal samples had taeniid eggs, while 4.4% (71/1621) contained Echinococcus spp. eggs. Area-wise, the faecal prevalence of Echinococcus spp. was 9.2% (48/524) in Turkana, 4.0% (20/500) in Maasai Mara, 0.7% (2/294) in Isiolo and 0.3% (1/303) in Meru. E. granulosus sensu stricto (s. s.) was the dominant Echinococcus taxon, followed by E. canadensis (G6/7) that was detected in 51 and 23 faecal samples, respectively. E. ortleppi was detected in only 5 faecal samples. We report for the first time the presence of E. felidis eggs in two dog faecal samples (from Maasai Mara region). Mixed infections of these taxa were also found in faecal samples, including: E. granulosus s. s. and E. canadensis (G6/7) (n = 7), E. granulosus s. s. and E. ortleppi (n = 1) and all three species (n = 1). The dog data presented here confirm the differences in diversity and abundance of Echinococcus spp. between regions of Kenya, correspond well with previously published data from livestock, and tentatively suggest a role of domestic dogs as a link between domestic and sylvatic cycles of Echinococcus spp.

Echinococcus granulosus genotypes in Iran: a systematic review

Cystic echinococcosis (CE) caused by Echinococcus granulosus sensu lato (s.l.) is a significant zoonosis, especially in developing countries of the Middle East, with many studies focusing on CE genotypes in Iran. We performed a systematic review to determine the exact status of E. granulosus genotypes in the country. We explored English (Pubmed, Scopus, ISI Web of Science and Science Direct) and Persian (Magiran, Iran Medex and Scientific Information Database) databases along with Google Scholar. Our review included 73 studies published prior to the end of 2015. In total, 2952 animal (intermediate and definitive) hosts were examined, and the prevalent genotypes comprised G1 (92.75%) and G6 (4.53%) in sheep, cattle, camels, goats and buffaloes; G3 (2.43%) in five herbivore hosts and dogs; G7 (0.2%) in sheep and goats; and G2 (0.06%) in dogs. G1 was mostly dominant in West Azerbaijan, whereas G3 and G6 were identified most frequently in the provinces of Isfahan and Fars, respectively. Regarding human CE infection, 340 cases were reported from Iran, with the identified genotypes G1 (n = 320), G6 (n = 13) and G3 (n = 7). Most CE-infected humans originated from Isfahan province (168 cases), whereas the lowest number of infected persons was noted in Kerman province (two cases). The information obtained from this systematic review is central to better understanding the biological and epidemiological characteristics of E. granulosus s.l. genotypes in Iran, leading to more comprehensive control strategies.

Cystic echinococcosis in Jordan: A review of causative species, previous studies, serological and radiological diagnosis

Cystic echinococcosis (CE)/hydatidosis is a zoonotic disease which occur in human and herbivore animals as a result of infection with the larval stage of the taeniid cestode Echinococcus granulosus sensu lato (s. l.). In human, CE is a serious public health concern in many parts of the world including Jordan. The present review will cover CE causative agent: E. granulosus species/genotypes; life cycle of E. granulosus parasite, all published previous studies on CE in Jordan (humans, intermediate hosts, definitive host) as well as its diagnostic methods in human.

Human cystic echinococcosis in Turkey: a preliminary study on DNA polymorphisms of hydatid cysts removed from confirmed patients

Cystic echinococcosis caused by the larval stages of Echinococcus granulosus sensu lato s.l is endemic in Turkey with a high public health impact particularly in rural areas. The aim of this study was to investigate the genetic variation and population structure of E. granulosus s.s using metacestode isolates removed from surgically confirmed patients originating from several regions in Turkey and to investigate the occurrence of autochthonous transmission. Using DNA extracted from a total of 46 human-derived CE isolates, we successfully analysed an 827-bp fragment within the cox1 mitochondrial gene and confirmed the causative agent of human cystic echinococcosis in patients included in this study to be Echinococcus granulosus s.s (G1 and G3 genotypes). The haplotype parsimony network consisted of 28 haplotypes arranged within three main clusters and the neutrality indices were both negative and significant indicating negative selection or population expansion. The assessment carried out in this study using GenBank nucleotide sequence data from Turkey for sheep and cattle hosts demonstrated the importance of autochthonous transmission with sheep, cattle and humans harbouring the same haplotypes. Further studies are required to investigate the biological significance, if any, of E. granulosus s.s haplotypes and the genetic variability of CE from human patients using longer nucleotide sequences and a larger sample set.

Genotype characterization of livestock and human cystic echinococcosis in Mazandaran province, Iran

Echinococcus granulosus is a helminth from the family Taeniidae, which causes cystic echinococcosis (CE) in humans and diverse livestock around the world. The identification of existing genotypes in different regions is a major step towards the prevention and establishment of control programmes for the disease. This study aimed to detect CE genotypes using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the internal transcribed spacer-1 (ITS1) gene and sequencing of the cytochrome c oxidase subunit 1 (Cox1) gene in isolates from the central part of Mazandaran province, northern Iran. Forty isolates were collected from sheep, 17 from cattle and 6 from human formalin-fixed paraffin-embedded tissues (FFPE). The ITS1 and Cox1 genes were successfully amplified by PCR in 41 and 42 samples, respectively. PCR-RFLP and sequencing showed that all isolates had the G1-G3 genotypes in this study. Out of 31 isolates subjected to sequencing for the Cox1 gene, 80.7% had the G1 genotype. G2 (16.1%) and G3 (3.2%) genotypes were observed in five sheep and one cattle samples, respectively. Five human isolates were also sequenced for the ITS1 gene, which showed that all samples belonged to the G1 genotype. Ten haplotypes were determined among the isolates by alignment analysis of the Cox1 gene. In summary, this study demonstrated that G1 was the dominant genotype circulating between humans and livestock in the studied region. Furthermore, high genotypic diversity among the CE isolates was observed.

The seroprevalence rate and population genetic structure of human cystic echinococcosis in the Middle East: A systematic review and meta-analysis

Cystic echinococcosis (CE) represents an increasing public health concern in many parts of the world, including the Middle East. The present study is the first systematic review and meta-analysis to assess the seroprevalence rate and population genetic structure of human CE in the eastern Mediterranean region. To estimate the population genetic structure, Echinococcus sequences of the cytochrome oxidase subunit 1 (cox1) gene isolated from countries from this geographical area were retrieved from the GenBank database. An electronic search for articles from 1990 until 2015 was performed using databases PubMed, ScienceDirect, and Scopus. A total of 53 articles reporting on CE seroprevalence and genotyping data met our eligibility criteria and were included in a meta-analysis. The overall CE seroprevalence rates in the general population and in individuals at high risk of infection were estimated using the random-effect model at 7.4% (95% CI = 4.8-10.6) and 10.7% (95% CI = 7.6-14.3), respectively. Risk factors including age group (P < 0.001), dog ownership (P = 0.03), residence area (P < 0.001), and educational level (P = 0.04) showed a statistically significant association with CE seroprevalence. A pairwise fixation index (Fst), used as an estimation of gene flow, suggested a moderate level of genetic differentiation between members of the E. granulosus sensu stricto (G1-G3) complex from Iranian and Turkish metapopulations (Fst = 0.171). The finding of common haplotypes may represent an ancestral transfer of alleles among populations probably during the early stages of animal domestication. The high CE seroprevalence rates found highlight the necessity of implementing appropriate public education for preventive and control strategies, particularly in individuals at high risk of infection; furthermore, our genetic findings reveal novel molecular data concerning microevolutionary events of Echinococcus isolates among Middle East countries.

Cystic echinococcosis in Turkana, Kenya: 30 years of imaging in an endemic region

Cystic echinococcosis (CE), a widespread, complex zoonosis, causes chronic disease associated with high morbidity. The pastoral Turkana people of Kenya have one of the highest prevalence rates of CE in the world. Between 1983 and 2015, a CE control program in the Turkana region used ultrasound (US) screening surveys and surgical outreach visits to evaluate CE prevalence and treat those with the disease. As the gold standard modality for diagnosing CE, US reveals a great deal of information about the disease in affected populations. The aim of this study is to discuss the characteristics of untreated CE in the Turkana people as revealed by US data collected during the CE control program and evaluate disease presentation, factors influencing the risk of transmission, and the timeline of disease progression. Data were obtained from written patient notes from US screenings and images; cysts were classified using the World Health Organization (WHO) standardized US classification of CE. Findings include greater prevalence of cysts, later stages of cysts, and multiple cysts in older age groups, with no multiple cysts occurring in patients under six years of age, which are consistent with the assertion that rates of exposure, transmission, and infection increase with age in endemic regions. Findings also raise questions regarding the timeline of disease progression, and factors potentially influencing disease transmission within this and other endemic populations. A comprehensive survey focusing on cultural and community observations (e.g., changing behaviors, hygienic practices, etc.) may provide more detailed information regarding factors that facilitate transmission.

Echinococcus spp. Tapeworms in North America

Alveolar and cystic echinococcosis are emerging and reemerging in Europe, Africa, and Asia. The expansion of Echinococcus spp. tapeworms in wildlife host reservoirs appears to be driving this emergence in some areas. Recent studies suggest a similar phenomenon may be occurring in North America. We describe the context of Echinococcus spp. research in North America, with a specific focus on the contiguous United States. Although studies were conducted in the United States throughout the 1900s on various sylvatic and domestic Echinococcus spp. tapeworm cycles, data are lacking for the past ≈30 years. We review previous research, provide analysis of more recent focal studies, and suggest that Echinococcus spp. tapeworms, in particular E. canadensis, may be underrecognized. As a result, we suggest that additional research and surveillance be conducted for these tapeworms in wildlife host reservoirs across the United States.

First molecular characterization of Echinococcus granulosus (sensu stricto) genotype 1 among cattle in Sudan

Background

Echinococcus granulosus sensu lato (s.l.) is the causative agent of cystic echinococcosis (CE), which is a cosmopolitan zoonotic parasitic disease infecting humans and a wide range of mammalian species including cattle. Currently, little information is available on the genetic diversity of Echinococcus species among livestock in Sudan. In the present study, fifty (n = 50) hydatid cysts were collected from cattle carcasses (one cyst sample per animal) at Al-kadarou slaughterhouse, Khartoum North, Sudan. DNA was extracted from protoscolices and the germinal layer of each cyst and subsequently amplified by PCR targeting the mitochondrial NADH dehydrogenase subunit 1 (NADH-1) gene. The amplified PCR products were purified and subjected to direct sequencing for subsequent construction of phylogenetic tree and net work analysis.

Results

The phylogenetic tree revealed the presence of Echinococcus canadenesis genotype 6 (G6) in 44 cysts (88.0%), Echinococcus ortleppi genotype 5 (G5) in 4 cysts (8.0%) and Echinococcus granulosus sensu stricto (s.s) genotype 1 (G1) in 2 cysts (4.0%). The phylogenetic network analysis revealed genetic variation among the different haplotypes/genotypes. This report has provided, for the first time, an insight of the role of cattle in the transmission of the zoonotic G1 echinococosis.

Conclusions

The results of the study illustrate that Sudanese breeds of cattle may play an important role in the transmission dynamics and the epidemiology of cystic echinococcosis in Sudan. This study reports the first molecular identification of E. granulosus s.s. in cattle in Central Sudan.

Increase of Vascular Endothelial Growth Factor and Decrease of MCP-1 and Some Updated Epidemiology Aspects of Cystic Echinococcosis Human Cases in Calabria Region

We aim to investigate some of the pathogenetic mediators of the human echinococcosis and to obtain updated epidemiological findings on cases of echinococcosis in Calabria, Southern Italy. Echinococcosis diagnosis was based on imaging, serological investigations, and molecular assay. Indeed, real-time PCR indicated the presence of G2/G3 genotypes of Echinococcus granulosus complex. Regarding pathogenesis, a relevant novel tool of immune depression should be deemed the reduced level of serum MCP-1. Also, we found a previously unreported VEGF, possibly associated with neovascularization requested by the parasite cyst metabolism. Cytokine profiles suggest a bias of the immunity toward Th2 and Treg responses. Nitric oxide levels exhibited a significant decrease one week after therapy versus basal level measured before surgery and/or chemotherapy. An increase of serum total IgE class and IgG4 subclass was found in Echinococcus-positive patients versus controls. Our data demonstrated an endemic spreading, at least in the province of Catanzaro and neighboring Calabria territories, for such parasitosis with the novel issue of the number of female overcoming male cases. In conclusion, the novel findings of this study were the increased VEGF and the reduced serum MCP-1 in the studied cases, as well as the number of Echinococcus-infected females overcoming the infected males.

Practical Algorisms for PCR-RFLP-Based Genotyping of Echinococcus granulosus Sensu Lato

Echinococcus granulosus sensu lato (s.l.) is a causative agent of cystic echinococcosis or cystic hydatid disease in humans and domestic and wild animals. The disease is a serious health problem in countries associated with poverty and poor hygiene practices, particularly in livestock raising. We introduced a practical algorism for genotyping the parasite, which may be useful to many developing countries. To evaluate the efficiency of the algorism, we genotyped 3 unknown strains isolated from human patients. We found that unknowns 1 and 3 were included in G1, G2, and G3 genotypes group and unknown 2 was included in G4 genotype (Echinococcus equinus) according to the algorisms. We confirmed these results by sequencing the 3 unknown isolates cox1 and nad1 PCR products. In conclusion, these new algorisms are very fast genotype identification tools that are suitable for evaluating E. granulosus s.l. isolated from livestock or livestock holders, particularly in developing countries.

The echinococcoses in Asia: The present situation

Human alveolar and cystic echinococcosis, caused by the accidental ingestion of eggs of the tapeworms Echinococcus multilocularis and Echinococcus granulosus sensu lato, respectively, are endemic in Asia. Various Echinococcus species are maintained in domesticated and/or wild mammals through predator-prey interactions. Molecular analysis is used to help differentiate infecting parasite species and genotypes, with the goal of better understanding parasite life cycles in order to aid in the planning and implementation of control programs. This paper discusses the various echinococcoses in Asia, with limited reference to neighboring areas, including parts of Central Asia, Russia, Europe and North America.

Limitations of the Echinococcus granulosus genome sequence assemblies for analysis of the gene family encoding the EG95 vaccine antigen

Echinococcus granulosus is an important zoonotic parasite that is distributed worldwide. The EG95 vaccine was developed to assist with control of E. granulosus transmission through the parasite's livestock intermediate hosts. The vaccine is based on a recombinant antigen encoded by a gene which is a member of a multi-gene family. With the recent availability of two E. granulosus draft genomes, we sought to map the eg95 gene family to the genomes. We were unable to map unequivocally any of the eg95 gene family members which had previously been characterized by cloning and sequencing both strands of genomic DNA fragments. Our inability to map EG95-related genes to the genomes has revealed limitations in the assembled sequence data when utilized for gene family analyses. This study contrasts with the expectations expressed in often high-profile publications describing draft genomes of parasitic organisms, highlighting deficiencies in currently available genomic resources for E. granulosus and provides a cautionary note for research which seeks to utilize these genome datasets.

A novel in silico minigene vaccine based on CD4+ T-helper and B-cell epitopes of EG95 isolates for vaccination against cystic echinococcosis

EG95 oncospheral antigen plays a crucial role in Echinococcus granulosus pathogenicity. Considering the diversity of antigen among different EG95 isolates, it seems to be an ideal antigen for designing a universal multivalent minigene vaccine, so-called multi-epitope vaccine. This is the first in silico study to design a construct for the development of global EG95-based hydatid vaccine against E. granulosus in intermediate hosts. After antigen sequence selection, the three-dimensional structure of EG95 was modeled and multilaterally validated. The preliminary parameters for B-cell epitope prediction were implemented such as the possible transmembrane helix, signal peptide, post-translational modifications and allergenicity. The high ranked linear and conformational B-cell epitopes derived from several online web-servers (e.g., ElliPro, BepiPred v1.0, BcePred, ABCpred, SVMTrip, IEDB algorithms, SEPPA v2.0 and Discotope v2.0) were utilized for multiple sequence alignment and then for engineering the vaccine construct. T-helper based epitopes were predicted by molecular docking between the high frequent ovar class II allele (Ovar-DRB1*1202) and hexadecamer fragments of the EG95 protein. Having used the immune-informatics tools, we formulated the first EG95-based minigene vaccine based on T-helper epitope with high-binding affinity to the ovar MHC allele. This designed construct was analyzed for different physicochemical properties. It was also codon-optimized for high-level expression in Escherichia coli k12. Taken all, we propose the present in silico vaccine constructs as a promising platform for the generation of broadly protective vaccines for species and genus-specific immunization of the natural hosts of the parasite.

Genetic characterization of Echinococcus granulosus strains isolated from humans based on nad1 and cox1 gene analysis in Isfahan, central Iran

Cystic echinococcosis (CE) is a medically important parasite-caused human disease. Humans may acquire the infection accidentally by ingestion of E. granulosus eggs. The parasite has a broad range of hosts and genotypes, which may affect its aetiological and biological characteristics. The present study aimed to determine the genetic characteristics of human isolates of E. granulosus in Isfahan, Iran. In this cross-sectional study, 50 surgically removed hydatid cysts were collected from hospitalized patients in Al-Zahra Hospital, Isfahan, Iran, over a period of 2 years (2015-2017). DNA was extracted from cyst material, and polymerase chain reactions (PCR) were performed targeting cox1 and nad1 genes. Amplicons were sequenced directly and the resulting sequences were aligned and analysed. Phylogenetic and genetic diversity analyses were also performed. Among the isolates, 43 (86%), 3 (6%) and 4 (8%) out of 50 were E. granulosus (G1), E. granulosus (G3) and E. intermedius (G6), respectively. In total, nine and eight haplotypes were identified by nad1 and cox1 gene analysis, respectively. The haplotype diversity index was higher by cox1 gene analysis (0.547) in G1 strains compared with nad1 (0.433). The G1 genotype was the most predominant isolate from human cases of CE, and the presence of G6 is indicative of an important role of camels in the development of human CE in Isfahan. This is the first report of the G3 genotype causing human CE in Isfahan. Moreover, cox1 gene analysis enables a higher resolution of the genetic diversity of the E. granulosus population compared with nad1 gene analysis.

Cystic echinococcosis in Poland: genetic variability and the first record of Echinococcus granulosus sensu stricto (G1 genotype) in the country

Cystic echinococcosis is one of the most important zoonotic diseases affecting humans and livestock worldwide, and is endemic in Poland. A set of six isolates on larval stages of Echinococcus granulosus sensu lato tapeworms collected from three humans, two pigs and one sheep from Polish foci of CE was examined by DNA sequencing of two mitochondrial genes (cox1, rrnS). The results demonstrated the presence of E. canadensis and E. granulosus sensu stricto in the investigated hydatid cysts. The former species was found in all five isolates from pigs and humans derived from central Poland. In a sheep hydatid cyst originating from Lesser Poland Voivodeship in southern Poland, E. granulosus s. s. (G1 genotype) was identified. This is the first report of an unambiguously autochthonous infection with E. granulosus s. s. in Poland. The global distribution and host affiliations of the commonly occurring G1 microvariant with nucleotide change 56C/T in cox1, detected here in Polish sheep, are discussed. The finding that sheep harboured E. granulosus s. s. may have important consequences for developing effective hydatid control programmes in Poland due to its longer maturation rate in dogs compared with E. canadensis G7. This may lead to greater expenditures for purchasing anthelmintics to provide an appropriate dosing regime in sheep-raising areas of the country.

Brain hydatidosis: review of the literature

Hydatidosis is a common disease worldwide. The causal agent may compromise any Organ of the body, the cerebral location is infrequent. The infection is caused by the larval form of Cestodo Echinococcus granulosus. The man is an accidental intermediary host for food consumption or water contaminated with eggs present in animal feces. We present a review of the literature. At the imaging level, the disease has a classic characteristic consisting of single, usually unilocular and less frequent multilocular, intra-axial and more frequently hemispheric cerebral lesions, compromising the vascular territory of the middle cerebral artery by the hematogenous dissemination of the parasite.

Genetic differentiation of the G6/7 cluster of Echinococcus canadensis based on mitochondrial marker genes

Among the genotype/species causing cystic echinococcosis, the taxonomic status of Echinococcus canadensis is only partially resolved. Within E. canadensis, four genotypes (G6, G7, G8 and G10) have been described based on short mitochondrial sequences, of which G6 and G7 (the 'camel' and the 'pig' strain, respectively) are closely related and variously regarded as microvariants of a single strain G6/7. Globally, this G6/7 cluster is the second most important agent of human cystic echinococcosis and is the predominant Echinococcus taxon in large parts of sub-Saharan Africa. To add data on the internal structure and the geographical distribution of this cluster, we analysed diversity and population structure of 296 isolates of E. canadensis from sub-Saharan Africa, the Middle East and Europe using the complete mitochondrial cytochrome c oxidase subunit 1 (cox1) (1,608bp) and NADH dehydrogenase subunit 1 (nad1) (894bp) gene sequences. Polymorphism of the mtDNA loci gave 51 (cox1), 33 (nad1) and 73 (cox1-nad1 concatenated) haplotypes. African and Middle Eastern isolates mainly grouped in a star-like structure around a predominant haplotype, while the European isolates produced more diversified networks. Although the cox1 diagnostic sequence for G6 is frequent in the African/Middle Eastern sub-cluster, and that for G7 is common in the European isolates, numerous intermediate variants prevent a clear distinction into 'G6' or 'G7', and the entire taxon is best treated as a common haplotype cluster G6/7. Meanwhile, the G6/7 cluster is clearly distinct from sequences of wildlife isolates of G8 and G10 from the northern hemisphere, and sequences of the latter genotypes were remarkably distant from each other. It is clear from the present study that, based on mitochondrial data, G6/7 is a coherent genotypic entity within E. canadensis that retains substantial intraspecific variance, and sub-populations share common ancestral polymorphisms and haplotypes. This study provides the basis for wider biogeographic comparison and population genetics studies of this taxon.

Genetic survey of alveolar and cystic echinococcoses in Romania: first molecular evidence of Echinococcus multilocularis in humans in the country

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are considered as one of the most important zoonotic diseases in Romania, where they are subject to mandatory reporting. To obtain more knowledge about the genetic diversity of Echinococcus causative agents of these diseases, 11 isolates from humans and ungulate intermediate hosts from the two regions of Romania were genotyped using mitochondrial markers. In clinical samples of five patients from north-eastern Romania (Iasi, Botosani, Vaslui counties), Echinococcus multilocularis was identified as causal agent by cox1 sequence analysis. To the best of our knowledge this finding presents the first molecular evidence of E. multilocularis in humans from Romania. Only two cases of AE in patients were previously documented in the country by serological methods. In our four patients the most widespread European variant E5 of E. multilocularis was recorded, whereas in isolate from Vaslui county three nucleotide substitutions were detected as compared to the most related E5 haplotype. One of these mutations (411T/G) matched N1 and N2 haplotypes described previously from North America. In six CE samples retrieved from western Romania (Caras-Severin and Timis counties), two human isolates were diagnosed as Echinococcus canadensis G7, one as E. granulosus s.s. G1 and one as E. granulosus s.s. G3 using atp6 and rrnS sequencing. In ungulates, the cattle isolate was allocated to E. granulosus s.s. G1 and pig isolate to E. canadensis G7. The two G7 findings in humans reinforced the recent view that G7 was underestimated as compared to the E. granulosus s.s. regarding human CE threat that can be further employed for identifying sources of infections and establishing suitable preventive measures.

Cystic Echinococcosis in Turkana, Kenya: The Role of Cross-Sectional Screening Surveys in Assessing the Prevalence of Human Infection

Cystic echinococcosis (CE) is a neglected zoonotic disease caused by Echinococcus granulosus. Infection leads to formation of cysts within the viscera of the human host. In the 1980s, the transhumant population of northwest Turkana, Kenya, was found to have the highest prevalence of CE in the world. In 1983, AMREF Health Africa and the Kenya Medical and Research Institute launched a CE Control Program in northwest Turkana, screening and treating the local people. This epidemiological study of CE in Turkana analyses approximately 30 years of surveillance and surgical data. Cyst data were categorized using the World Health Organization CE ultrasound classification system before being analyzed for cyst, patient, and population characteristics, and surveillance data from 1985 are compared with more recent surveillance data to assess changes in prevalence in the control region since the commencement of control activities. In 1985, the prevalence of CE among the Turkana was 5.6%. In 2010-2011 and 2011-2012, calculated CE prevalence rates were 1.9% and 3.8%, respectively. Since the 1980s, the age distribution of people with CE in Turkana has shifted: initially, cases of CE appeared predominantly within younger age groups, but recent data reveal a higher prevalence within older age groups. The frequency of infection in females also significantly decreased. The reduction in CE prevalence from 5.6% in the 1980s to 1.9-3.8% in 2010-2012 and the shift in age distribution of CE-infected individuals over time indicate that the prevalence of CE in Turkana has decreased since the control program began.

Genetic characterization of human hydatid cysts shows coinfection by Echinococcus canadensis G7 and Echinococcus granulosus sensu stricto G1 in Argentina

Human cystic echinococcosis caused by the larval stage of Echinococcus granulosus sensu lato (s.l.) is a highly endemic disease in the province of Neuquén, Patagonia, Argentina. Human infections with E. granulosus sensu stricto (s.s.) G1 and Echinococcus canadensis G6 were reported in Neuquén in previous studies, whereas four genotypes were identified in livestock: G1, G3, G6, and G7. The aim of this study was to identify the genotypes of E. granulosus s.l. isolates from humans of Neuquén province, Patagonia, Argentina, through the 2005-2014 period. Twenty six hydatid cysts were obtained from 21 patients. The most frequent locations were the liver and lungs. Single cysts were observed in 81.0% of patients, and combined infection of liver and lungs was detected in 9.5% of cases. Partial sequencing of mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes identified the presence of E. granulosus s.s. G1 (n = 11; 42.3%) including three different partial sequences; E. canadensis G6 (n = 14; 53.8%) and E. canadensis G7 (n = 1; 3.9%). Coinfection with G1 and G7 genotypes was detected in one patient who harbored three liver cysts. Most of the liver cysts corresponded to G1 and G6 genotypes. This study presents the first report in the Americas of a human infection with E. canadensis G7 and the second worldwide report of a coinfection with two different species and genotypes of E. granulosus s.l in humans. The molecular diversity of this parasite should be considered to redesign or improve the control program strategies in endemic regions.

In vitro and in vivo antihydatid activity of a nano emulsion of Zataria multiflora essential oil

In in vitro process of this study, protoscoleces of the hydatid cysts were exposed to two concentrations of nano emulsion (NE) of Zataria multiflora essential oil (ZMEO) (1 and 2mg/mL) for 10 and 20min. Viability of protoscoleces was confirmed using 0.1% eosin staining. For in vivo studies, sixteen laboratory mice were infected intraperitoneally by 1500 live protoscoleces. Five months after infection, the infected mice were divided into treatment and control groups. The mice of treatment group received the NE of ZMEO (20mg/kg) orally via their drinking water while the mice of control group received no treatment. Two months after the start of treatment, all of the mice were necropsied and the hydatid cysts were collected. Subsequently, the numbers, sizes and weights of the collected cysts were compared between the mice of two groups. The results of in vitro scolicidal assays showed that the scolicidal power of NE of a ZMEO at concentration of 1mg/mL was 88.01%, and 100% after 10 and 20min respectively. NE of ZMEO showed 100% scolicidal power at a concentration of 2mg/mL after 10min (comparing to 4.46% for the control group). The results of in vivo studies revealed that the size of the largest cysts as well as the total number of the cysts were significantly lower in the mice treated with NE of ZMEO (P<0.05). In conclusion, NE of ZMEO may be considered as a natural scolicidal agent and a potential therapeutic tool for treatment of hydatid disease.

Evaluation of the impact of 2 years of a dosing intervention on canine echinococcosis in the Alay Valley, Kyrgyzstan

Echinococcosis is a re-emerging zoonotic disease in Kyrgyzstan. In 2012, an echinococcosis control scheme was started that included dosing owned dogs in the Alay Valley, Kyrgyzstan with praziquantel. Control programmes require large investments of money and resources; as such it is important to evaluate how well these are meeting their targets. However, problems associated with echinococcosis control schemes include remoteness and semi-nomadic customs of affected communities, and lack of resources. These same problems apply to control scheme evaluations, and quick and easy assessment tools are highly desirable. Lot quality assurance sampling was used to assess the impact of approximately 2 years of echinococcosis control in the Alay valley. A pre-intervention coproELISA prevalence was established, and a 75% threshold for dosing compliance was set based on previous studies. Ten communities were visited in 2013 and 2014, with 18–21 dogs sampled per community, and questionnaires administered to dog owners. After 21 months of control efforts, 8/10 communities showed evidence of reaching the 75% praziquantel dosing target, although only 3/10 showed evidence of a reduction in coproELISA prevalence. This is understandable, since years of sustained control are required to effectively control echinococcosis, and efforts in the Alay valley should be and are being continued.

Gastrointestinal parasites of canids, a latent risk to human health in Tunisia

BACKGROUND

Although data on the parasite environmental contamination are crucial to implement strategies for control and treatment, information about zoonotic helminths is very limited in Tunisia. Contamination of areas with canid faeces harboring infective parasite elements represents a relevant health-risk impact for humans. The aim of this study was to assess the environmental contamination with eggs and oocysts of gastrointestinal parasites of dogs and wild canids in Tunisia with special attention to those that can be transmitted to humans.

RESULTS

One thousand two hundred and seventy faecal samples from stray dogs and 104 from wild canids (red foxes and golden jackals) were collected from different geographical regions throughout Tunisia. The helminth eggs and protozoan oocysts were concentrated by sucrose flotation and identified by microscopic examination. The most frequently observed parasites in dog samples were Toxocara spp. (27.2%), E. granulosus (25.8%), and Coccidia (13.1%). For wild canid faeces, the most commonly encountered parasites were Toxocara spp. (16.3%) followed by Capillaria spp. (9.6%). The parasite contamination of dog faeces varied significantly from one region to another in function of the climate.

CONCLUSION

To our knowledge, the study highlights for the first time in Tunisia a serious environmental contamination by numerous parasitic stages infective to humans. Efforts should be made to increase the awareness of the contamination risk of such parasites in the environment and implement a targeted educational program.

Presentation of secondary parasitic infection 37 years after primary infection

Echinococcus granulosus (EG) is a neglected pathology that causes cystic echinococcosis and primarily affects the liver and lung. EG infects ~6 million worldwide and mortality is quoted as 2-4% per 100 000 inhabitants. The increase in human traffic from endemic regions demands clinician's awareness. Dogs are the most common definitive host for the EG tapeworm. Human infection requires ingestion of fecal parasitic eggs. Primary infection causes cysts to appear in affected organs, rupture of which leads to secondary infection. Ultrasound remains the mainstay of diagnosis. Treatment can be either; chemotherapeutic, radiological, surgical or a combination depending on the organ affected.

Echinococcus granulosus ss in dog - A report in center-northern Portugal

Routine parasitic control and health care of the dog is lacking in many Portuguese rural communities. Freely roaming and stray dogs are responsible for the maintenance of a permanent parasitic infection pressure, namely of zoonotic importance. Therefore, a good understanding of the epidemiology of Echinococcus granulosus including the transmission to man is of great significance to further the awareness within the rural populations and the local health authorities of this zoonotic parasite. This report aims at a better understanding of the epidemiology of Echinococcus granulosus in the Cantanhede region, located in the Central region of Portugal, through the necropsy of stray dogs. At the Official Veterinary Kennel of this Municipality, 105 stray dogs were studied for the presence of Echinococcus granulosus following the adult cestode recovery with necropsy procedure of the first third part of the small intestine. One dog revealed to be positive (1.05%) and the sampled Echinococcus were genotyped and identified as E. granulosus ss. As this genotype is widely spread and has been reported in different parts of the world, further work is necessary to be conducted in this and other regions of Portugal for a better understanding of E. granulosus epidemiology within the typical small rural farms where pig rearing plays an important economic role.

Is there echinococcosis in West Africa? A refugee from Niger with a liver cyst

BACKGROUND

Italy is presently facing an increase in immigration from sub-Saharan Africa through the Mediterranean Sea. Case reports of human cystic echinococcosis (CE) have been reported from most sub-Saharan countries. Therefore, an increase in the number of patients with CE coming from these areas in the Italian and European centers for infectious diseases is expected. Unfortunately, the epidemiology of CE in sub-Saharan countries is poorly known, which makes clinical suspicion and diagnosis of such infection difficult in patients coming from these areas.

RESULTS

Here we report a case of hepatic CE in a patient from Niger who arrived in Italy through Libya and visited in a Tropical Medicine referral center in Northern Italy. The parasite was identified molecularly as the G6 "camel" strain of Echinococcus granulosus (E. canadensis). The diagnosis and management of a chronic and clinically complex infection like CE in such situation is difficult. Only 40 cases of CE from Niger have been reported; of these, 75% had extra-hepatic localization. To our knowledge, no strain characterization of human isolates from Niger has been reported so far. The CE cyst of the patient was in CE3a stage, indicating active transmission from the area in which the patient came. However, prevalence data from Niger, and from any other country in West Africa, are almost inexistent.

CONCLUSIONS

We argue that population epidemiology surveys with ultrasound are warranted in Sahelian countries, including Niger. These studies could improve the knowledge of CE epidemiology, provide health authorities with important information for public health interventions targeting this zoonosis, and shed light on any difference between tissue tropism and clinical manifestations caused by the different E. granulosus strains.

New mitogenome and nuclear evidence on the phylogeny and taxonomy of the highly zoonotic tapeworm Echinococcus granulosus sensu stricto

Cystic echinococcosis, a zoonotic disease caused by Echinococcus granulosus sensu lato (s. l.), is a significant global public health concern. Echinococcus granulosus s. l. is currently divided into numerous genotypes (G1-G8 and G10) of which G1-G3 are the most frequently implicated genotypes in human infections. Although it has been suggested that G1-G3 could be regarded as a distinct species E. granulosus sensu stricto (s. s.), the evidence to support this is inconclusive. Most importantly, data from nuclear DNA that provide means to investigate the exchange of genetic material between G1-G3 is lacking as none of the published nuclear DNA studies have explicitly included G2 or G3. Moreover, the commonly used relatively short mtDNA sequences, including the complete cox1 gene, have not allowed unequivocal differentiation of genotypes G1-G3. Therefore, significantly longer mtDNA sequences are required to distinguish these genotypes with confidence. The main aim of this study was to evaluate the phylogenetic relations and taxonomy of genotypes G1-G3 using sequences of nearly complete mitogenomes (11,443bp) and three nuclear loci (2984bp). A total of 23 G1-G3 samples were analysed, originating from 5 intermediate host species in 10 countries. The mtDNA data demonstrate that genotypes G1 and G3 are distinct mitochondrial genotypes (separated by 37 mutations), whereas G2 is not a separate genotype or even a monophyletic cluster, but belongs to G3. Nuclear data revealed no genetic separation of G1 and G3, suggesting that these genotypes form a single species due to ongoing gene flow. We conclude that: (a) in the taxonomic sense, genotypes G1 and G3 can be treated as a single species E. granulosus s. s.; (b) genotypes G1 and G3 should be regarded as distinct genotypes only in the context of mitochondrial data; (c) we recommend excluding G2 from the genotype list.

The first report of two cases of cystic echinococcosis in the lung by Echinococcus ortleppi infection, in Vietnam

In 2013, two cases of infection by Echinococcus that caused cystic echinococcosis in the lungs were reported. In the first case, there was a cyst of 6 × 7 cm in diameter, and in the second case, there were four cysts of 5 × 6 cm, 4 × 4 cm, 3.5 × 3 cm and 2.5 × 2 cm in diameter, respectively. In both cases, Echinococcus larvae were collected from the cysts. The larvae were identified as Echinococcus ortleppi by morphology and a molecular method (using reduced nicotinamide adenine dinucleotide hydrogenase [NADH] with 99%-100% homology compared with E. ortleppi in GenBank). This is the first time that this species has been found in humans in Vietnam.

A possible Echinococcus granulosus calcified cyst found in a medieval adult female from the churchyard of Santo Domingo de Silos (Prádena del Rincón, Madrid, Spain)

Calcification, or mineralisation, can occur as part of a natural process, or by pathological processes. The purpose of this work is to examine an unidentified semi-spherical and perforate hollow mass, found near the pelvis of an adult female, dated 12th-13th century AD, exhumed of the Church of Santo Domingo de Silos (Prádena del Ricón, Madrid, Spain). The mass was examined by SEM and Energy Dispersive X-Ray Spectroscopy. These procedures revealed a heterogeneous inner surface with both smooth and irregular areas. A larger spherical and several smaller crescent-shaped perforations were noticed. X-ray microanalysis revealed the presence of the elements C, K, P, Ca, Al, Si, Fe, and Mg. The co-localisation of Ca and P suggests that they may be combined in a mineral matrix, likely formed in vivo. Other minerals probably came from the soil, although Fe could be related to the presence of blood. The macroscopic and microscopic appearances, chemical composition, and location of the calcified mass point to a possible hydatid cyst from Echinococcus granulosus, common in agricultural populations. This study used a suite of analytical techniques that are useful in the diagnosis of unknown calcified masses and can, therefore, be recommended for use in future analytical work.

The Echinococcus canadensis (G7) genome: a key knowledge of parasitic platyhelminth human diseases

BACKGROUND

The parasite Echinococcus canadensis (G7) (phylum Platyhelminthes, class Cestoda) is one of the causative agents of echinococcosis. Echinococcosis is a worldwide chronic zoonosis affecting humans as well as domestic and wild mammals, which has been reported as a prioritized neglected disease by the World Health Organisation. No genomic data, comparative genomic analyses or efficient therapeutic and diagnostic tools are available for this severe disease. The information presented in this study will help to understand the peculiar biological characters and to design species-specific control tools.

RESULTS

We sequenced, assembled and annotated the 115-Mb genome of E. canadensis (G7). Comparative genomic analyses using whole genome data of three Echinococcus species not only confirmed the status of E. canadensis (G7) as a separate species but also demonstrated a high nucleotide sequences divergence in relation to E. granulosus (G1). The E. canadensis (G7) genome contains 11,449 genes with a core set of 881 orthologs shared among five cestode species. Comparative genomics revealed that there are more single nucleotide polymorphisms (SNPs) between E. canadensis (G7) and E. granulosus (G1) than between E. canadensis (G7) and E. multilocularis. This result was unexpected since E. canadensis (G7) and E. granulosus (G1) were considered to belong to the species complex E. granulosus sensu lato. We described SNPs in known drug targets and metabolism genes in the E. canadensis (G7) genome. Regarding gene regulation, we analysed three particular features: CpG island distribution along the three Echinococcus genomes, DNA methylation system and small RNA pathway. The results suggest the occurrence of yet unknown gene regulation mechanisms in Echinococcus.

CONCLUSIONS

This is the first work that addresses Echinococcus comparative genomics. The resources presented here will promote the study of mechanisms of parasite development as well as new tools for drug discovery. The availability of a high-quality genome assembly is critical for fully exploring the biology of a pathogenic organism. The E. canadensis (G7) genome presented in this study provides a unique opportunity to address the genetic diversity among the genus Echinococcus and its particular developmental features. At present, there is no unequivocal taxonomic classification of Echinococcus species; however, the genome-wide SNPs analysis performed here revealed the phylogenetic distance among these three Echinococcus species. Additional cestode genomes need to be sequenced to be able to resolve their phylogeny.

Implementation of new tools in molecular epidemiology studies of Echinococcus granulosus sensu lato in South America

The aim of this work was to determine Echinococcus granulosus sensu lato species and genotypes in intermediate and definitive hosts and in human isolates from endemic regions of Argentina and Brazil including those where no molecular data is available by a combination of classical and alternative molecular tools. A total of 227 samples were isolated from humans, natural intermediate and definitive hosts. Amplification of cytochrome c oxidase subunit I gene fragment was performed and a combination of AluI digestion assay, High Resolution Melting analysis (HRM) assay and DNA sequencing was implemented for Echinococcus species/genotype determination. E. granulosus sensu stricto (G1) was found in sheep (n=35), cattle (n=67) and dogs (n=5); E. ortleppi (G5) in humans (n=3) and cattle (n=108); E. canadensis (G6) in humans (n=2) and E. canadensis (G7) in pigs (n=7). We reported for the first time the presence of E. ortleppi (G5) and E. canadensis (G6) in humans from San Juan and Catamarca Argentinean provinces and E. canadensis (G7) in pigs from Cordoba Argentinean province. In this work, we widened molecular epidemiology studies of E. granulosus s. l. in South America by analyzing several isolates from definitive and intermediate hosts, including humans from endemic regions were such information was scarce or unavailable. The presence of different species/genotypes in the same region and host species reinforce the need of rapid and specific techniques for accurate determination of Echinococcus species such as the ones proposed in this work.

Molecular characterization of Echinococcus granulosus isolates from Bulgarian human cystic echinococcosis patients

Although cystic echinococcosis (CE) is highly endemic in Bulgaria, there is still scarce information about species and/or genotypes of the Echinococcus granulosus complex that infect humans. Our study tackled the genetic diversity of E. granulosus complex in a cohort of 30 Bulgarian CE patients. Ten animal E. granulosus isolates from neighboring Greece were additionally included. Specimens were comparatively analyzed for partial sequences of five mitochondrial (mt) (cox I, nad I, rrnS, rrnL, and atp6) and three nuclear (nc) genes (act II, hbx 2, and ef-1α) using a PCR-sequencing approach. All 30 Bulgarian isolates were identified as E. granulosus sensu stricto (s.s.) and were showing identical sequences for each of the three examined partial nc gene markers. Based upon concatenated sequences from partial mtDNA markers, we detected 10 haplotypes: 6 haplotypes (H1-H6) clustering with E. granulosus s.s. (G1) and 4 haplotypes (H9-H13) grouping with E. granulosus s.s. (G3), with H1 and H10 being the most frequent in Bulgarian patients. The haplotypes H1, H4, and H11 were also present in Greek hydatid cyst samples of animal origin. In conclusion, E. granulosus s.s. (G1 and G3 genotypes) is the only causative agent found so far to cause human CE in Bulgaria. However, further studies including larger sample sizes and other additional geographic regions in Bulgaria will have to be performed to confirm our results.

Global Distribution of Alveolar and Cystic Echinococcosis

Alveolar echinococcosis (AE) and cystic echinococcosis (CE) are severe helminthic zoonoses. Echinococcus multilocularis (causative agent of AE) is widely distributed in the northern hemisphere where it is typically maintained in a wild animal cycle including canids as definitive hosts and rodents as intermediate hosts. The species Echinococcus granulosus, Echinococcus ortleppi, Echinococcus canadensis and Echinococcus intermedius are the causative agents of CE with a worldwide distribution and a highly variable human disease burden in the different endemic areas depending upon human behavioural risk factors, the diversity and ecology of animal host assemblages and the genetic diversity within Echinococcus species which differ in their zoonotic potential and pathogenicity. Both AE and CE are regarded as neglected zoonoses, with a higher overall burden of disease for CE due to its global distribution and high regional prevalence, but a higher pathogenicity and case fatality rate for AE, especially in Asia. Over the past two decades, numerous studies have addressed the epidemiology and distribution of these Echinococcus species worldwide, resulting in better-defined boundaries of the endemic areas. This chapter presents the global distribution of Echinococcus species and human AE and CE in maps and summarizes the global data on host assemblages, transmission, prevalence in animal definitive hosts, incidence in people and molecular epidemiology.

Laboratory Diagnosis of Echinococcus spp. in Human Patients and Infected Animals

Among the species composing the genus Echinococcus, four species are of human clinical interest. The most prevalent species are Echinococcus granulosus and Echinococcus multilocularis, followed by Echinococcus vogeli and Echinococcus oligarthrus. The first two species cause cystic echinococcosis (CE) and alveolar echinococcosis (AE) respectively. Both diseases have a complex clinical management, in which laboratory diagnosis could be an adjunctive to the imaging techniques. To date, several approaches have been described for the laboratory diagnosis and followup of CE and AE, including antibody, antigen and cytokine detection. All of these approaches are far from being optimal as adjunctive diagnosis particularly for CE, since they do not reach enough sensitivity and/or specificity. A combination of several methods (e.g., antibody and antigen detection) or of several (recombinant) antigens could improve the performance of the adjunctive laboratory methods, although the complexity of echinococcosis and heterogeneity of clinical cases make necessary a deep understanding of the host-parasite relationships and the parasite phenotype at different developmental stages to reach the best diagnostic tool and to make it accepted in clinical practice. Standardization approaches and a deep understanding of the performance of each of the available antigens in the diagnosis of echinococcosis for the different clinical pictures are also needed. The detection of the parasite in definitive hosts is also reviewed in this chapter. Finally, the different methods for the detection of parasite DNA in different analytes and matrices are also reviewed.