Genetic diversity and transmission patterns of Echinococcus granulosus sensu stricto among domestic ungulates of Sardinia, Italy

Cystic echinococcosis (CE), a parasitic zoonosis of public health and economic concern, is highly endemic in Sardinia, Italy. The study involved examining the intraspecific variability and demographic structure of Echinococcus granulosussensu stricto (s.s.) in common hosts of this parasite. Molecular surveillance included the fragment amplification of a partial mitochondrial gene, cox1 (750 bp), for a total of 69 isolates derived from sheep (n = 52), cattle (n = 11), pigs (n = 4), and goats (n = 2). It was ascertained that E. granulosus s.s. was the primary agent of infection among these ungulates and G1 genotype was highly prevalent (79.71%). Considerable intraspecific variation was found, revealing the existence of 22 haplotypes with relatively high haplotype (0.8555 ± 0.033) and low nucleotide diversities (0.00281 ± 0.00030). Population demographics indicated an expanding parasitic population signifying negative deviation from neutrality indices. Little genetic differentiation was found between the subpopulations of E. granulosus s.s. in the island. Moreover, the geographic dispersal of genotypes G1 and G3 also indicated similarity between Sardinian and mainland Echinococcus granulosus s.s. populations reaffirming the sympatric occurrence and efficient transmission of G1 and G3 genotypes. Molecular survey of CE has the potential to yield baseline information on the infective genotypes among the intermediate hosts and helps in devising suitable control strategies for curtailing the disease.

Genetic diversity of Echinococcus multilocularis and Echinococcus granulosus sensu lato in Kyrgyzstan: The A2 haplotype of E. multilocularis is the predominant variant infecting humans

Alveolar and cystic echinococcosis (AE, CE) caused by E. multilocularis and E. granulosus s.l., respectively, are considered emerging zoonotic diseases in Kyrgyzstan with some of the world highest regional incidences. Little is known regarding the molecular variability of both species in Kyrgyzstan. In this study we provide molecular data from a total of 72 parasite isolates derived from humans (52 AE and 20 CE patients) and 43 samples from dogs (23 infected with E. multilocularis and 20 with E. granulosus s.l.).Genetic variability in E. multilocularis was studied using the concatenated complete sequences of the cob, nad2 and cox1 mitochondrial genes adding a total of 3,558bp per isolate. The cob/nad2/cox1 A2 haplotype was identified in 63.4% of the human and in 65.2% of the dog samples. This haplotype was originally described in samples from Kazakhstan and St. Lawrence Island (Alaska, USA). We also describe here 16 non-previously defined variants of E. multilocularis (called A11-A26). All haplotypes cluster together within the Asian group in the haplotype network. Based on Fst values, low level of genetic differentiation was found between the populations of E. multilocularis isolated from different regions within the country. However, high degree of differentiation was found when all the concatenated sequences from Kyrgyzstan are considered as a single population and compared with the population of the parasite from the neighbouring country China. In the case of E. granulosus s.l. the analysis was based in 1,609bp of the cox1 gene. One isolate from a dog was identified as E. equinus, while all the other sequences were identified belonging to E. granulosus s.s. In total, 24 cox1 haplotypes of E. granulosus s.s. were identified including the already described variants: Eg01 (in 6 samples), Eg33 (in 4 samples), EgCl04 (in 2 samples), Eg03 (in 1 sample) and Eg32 (in 1 sample). From the twenty-five other isolates of E. granulosus s.s. a total of 19 non-previously described cox1 haplotypes were identified and named as EgKyr1 to EgKyr19. The most common haplotype infecting human is the EgKyr1 which was found in 5 isolates.The cob/nad2/cox1 A2 haplotype of E. multilocularis is responsible for the majority of human infections in Kyrgyzstan and is also found in the majority of dogs included in this study. Further similar studies in different parts of Asia could elucidate if it is also the most common variant infecting humans in other countries. It remains unknown if this particular haplotype presents differences in virulence which could have contributed to the emergency of alveolar echinococcosis in Kyrgyzstan. In the case of E. granulosus s.s. it seems that there is no dominant haplotype infecting humans in Kyrgzstan. Further characterization of biological or antigenic features of dominant mitochondrial haplotypes could help to elucidate if they present differences which could be relevant in the diagnostic, pathogenicity or in the host/parasite interaction when infecting humans.

Analysis of the genetic variability in Echinococcus species from different endemic countries have contributed to the knowledge in the taxonomy and phylogeography of these parasites. The most important species of this genus, Echinococcus granulosus sensu lato and Echinococcus multilocularis, co-exist in Kyrgyzstan causing serious public health issues. E. granulosus s.l. causes cystic echinococcosis and E. multilocularis is the causative agent of alveolar echinococcosis. The most relevant finding of our study is the identification of the cob/nad2/cox1 A2 haplotype of E. multilocularis as the most commonly found in humans and dogs. However, it remains unknown if this variant of E. multilocularis, based on genetic differences in mitochondrial genes, presents differences in virulence which could have contributed to the emergence of alveolar echinococcosis in Kyrgyzstan. The results also show a number of non-previously described genetic variants of E. multilocularis and E. granulosus s.s.

[Phylogenetic analysis of Echinococcus granulosus genotypes based on the GenBank database]

OBJECTIVE

To analyze the sequences of the cytochrome C oxidase subunit I (Cox1) gene of various Echinococcus granulosus genotypes that are currently recorded in the GenBank database, so as to investigate the genetic variation and differentiation of the E. granulosus genotypes across the world.

METHODS

The sequences of the Cox1 gene of various E. granulosus genotypes that are currently recorded in the GenBank database were collected, and the same sequences of the Cox1 gene identified from a region were excluded. The mutation sites among the Cox1 gene sequences were identified and a phylogenetic tree was created based on the Cox1 gene.

RESULTS

Transversion mutation was the predominant type of mutation in the Cox1 gene of E. granulosus. The same Cox1 gene sequence was found in E. granulosus G1, G6 and G7 genotypes isolated from various geographical locations across the world, with the corresponding GenBank accession numbers of KY766891, MH300971 and MH301007, respectively. Phylogenetic analysis revealed that E. granulosus G10 genotype had a remarkable geographical aggregation.

CONCLUSIONS

E. granulosus G1, G6 and G7 genotypes have primitive Cox1 gene sequences. There is a geographical aggregation of the E. granulosus G10 genotype in the phylogenetic tree, which has a tendency towards reproductive isolation.

A novel protocol to isolate, detect and differentiate taeniid eggs in leafy greens and berries using real-time PCR with melting curve analysis

BACKGROUND

Zoonotic taeniid cestodes are amongst the most important food-borne parasites affecting human health worldwide. Contamination of fresh produce with the eggs of Echinococcus granulosus (s.l.), Echinococcus multilocularis, and some Taenia species pose a potential food safety risk. However, very few studies have attempted to investigate the potential contamination of fresh produce with taeniid eggs and the available methods are not standardized for this purpose. Established protocols do exist for testing leafy greens and berries for contamination with protozoan parasites and are used in national surveillance programmes. This methodology could be suitable for the detection of taeniids. The objective of this project was to develop and standardize a sensitive and reliable method to detect contamination of leafy greens and berries with eggs of zoonotic taeniids and to differentiate between E. multilocularis, E. granulosus (s.l.) and Taenia spp.

METHODS

We compared the efficacy of different wash solutions to remove Taenia spp. eggs from spiked produce, assessed two DNA extraction kits for their performance on Taenia spp. eggs, and adapted a published conventional multiplex PCR into a real-time PCR with fluorescence melting curve analysis (MCA) that was optimized for use on produce washes. Analytical specificity of this protocol was assessed using non-spiked produce washes as well as a variety of other potentially contaminating parasites.

RESULTS

The protocol as established in this study had an analytical sensitivity of detecting five eggs per spiked sample for both romaine lettuce and strawberries. Unequivocal identification of E. multilocularis, E. granulosus (s.l.) and Taenia spp. was possible through MCA. Amplicon sequencing allowed identification of Taenia to the species level. The real-time PCR also amplified DNA from Dicrocoelium sp., but with a clearly discernable melting curve profile.

CONCLUSION

The new protocol for screening produce for taeniid contamination was highly sensitive. Melting curve analysis and the possibility of amplicon sequencing made this assay very specific. Once further validated, this method could be employed for surveillance of produce for contamination with taeniid parasites to assess potential risks for consumers.

Variability of the EG95 antigen-coding gene of Echinococcus granulosus in animal and human origin: implications for vaccine development

In the present study, the genetic variability of the EG95 protein-coding gene in several animal and human isolates of Echinococcus granulosus was investigated. A total of 24 isolates collected from cattle, buffalo, sheep, goat, dog and man were amplified by Eg95-coding gene-specific primers. From the generated sequence information, a conceptual amino acid sequence was deduced. Phylogenetically, the Eg95 coding gene belongs to the Eg95-1/Eg95-2/Eg95-3/Eg95-4 cluster. Further confirmation on the maximum composite likelihood analysis revealed that the overall transition/transversion bias was 2.913. This finding indicated thatthere is bias towards transitional and transversional substitution. Using artificial neural networks, a B-cell epitope was predicted on primary sequence information. Stretches of amino acid residues varied between animal and human isolates when hydrophobicity was considered. Flexibility also varied between larval and adult stages of the organism. This observation is important to develop vaccines. However, cytotoxic T-lymphocyte epitopes on primary sequence data remained constant in all isolates. In this study, agretope identification started with hydrophobic amino acids. Amino acids with the same physico-chemical properties were present in the middle. The conformational propensity of the Eg95-coding gene of 156 amino acid residues had α-turns and β-turns, and α-amphipathic regions up to 129, 138-156 and 151-155 residues, respectively. The results indicated potential T-cell antigenic sites. The overall Tajima's D value was negative (-2.404165), indicative of negative selection pressure.

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 relationship between the Echinococcus granulosus sensu stricto cysts located in lung and liver of hosts

G1 genotype of Echinococcus granulosus sensu stricto is the major cause of hydatidosis in Northern Africa, Tunisia included. The genetic relationship between lung and liver localization were studied in ovine, bovine and human hydatid cysts in Tunisia. Allozyme variation and single strand conformation polymorphism were used for genetic differentiation. The first cause of genetic differentiation was the host species and the second was the localization (lung or liver). The reticulated genetic relationship between the liver or the lung human isolates and isolates from bovine lung, is indicative of recombination (sexual reproduction) or lateral genetic transfer. The idea of two specialized populations (one for the lung one for the liver) that are more or less successful according to host susceptibility is thus proposed.

A novel PCR-RFLP assay for molecular characterization of Echinococcus granulosus sensu lato and closely related species in developing countries

Cystic echinococcosis, due to Echinococcus granulosus sensu lato (s. l.), currently affects three million people, especially in low-income countries and results in high livestock production loss. DNA-based methods demonstrated genetic variability of E. granulosus s. l., and five species were recognized to belong to the complex, including E. granulosus sensu stricto (s.s) (genotypes G1-G3), Echinococcus equinus (genotype G4), Echinococcus ortleppi (genotype G5), Echinococcus canadensis (genotypes G6-G10), and the lion strain Echinococcus felidis. The characterization of Echinococcus species responsible for human and animal echinococcosis is crucial to adapt the preventive measures against this parasitic disease. The sequencing approach is the gold standard for genotyping assays. Unfortunately, developing countries do not often have access to these techniques. Based on in silico RFLP tools, we described an accurate PCR-RFLP method for Echinococcus spp. characterization. The double digestion with the HaeIII and HinfI restriction enzymes of the PCR product from nad1 gene (1071 bp) led to a clear discrimination between E. granulosus s. l. and most closely related species (Echinococcus shiquicus and Echinococcus multilocularis).Molecular procedures and phylogenetic analysis confirmed the efficiency and the reproducibility of this simple and fast PCR-RFLP method. This technique is proved useful for fresh/unfixed and FF-PET tissues and enables large-scale molecular epidemiological screening in developing countries.

Molecular characterization of cystic echinococcosis: First record of G7 in Egypt and G1 in Yemen

Few molecular studies have identified the current status of cystic echinococcosis in Egypt. The present study aimed to ascertain the genotype(s) of Echinococcus granulosus responsible for human hydatidosis in different Egyptian governorates (regions). Animal isolates were collected from 40 camels, 5 pigs and 44 sheep. 27 human isolates were included in the present study. Specific PCR was performed and followed by DNA sequencing for mitochondrial 12S ribosomal RNA gene and BLAST analysis.The sheep cysts were not hydatid cysts. G6 genotype (camel starin) predominates in human, camel and pig isolates. G7 genotype (pig strain) was detected in two human isolates and one pig isolate. G1 genotype (sheep strain) was detected in one human isolate from Yemen and in no animal isolates. This is the first record of G7 in Egypt and G1 in Yemen.

Genomic characterization of EmsB microsatellite loci in Echinococcus multilocularis

EmsB is a molecular marker applied to Echinococcus multilocularis genotyping studies. This marker has largely been used to investigate the epidemiology of the parasite in different endemic foci. The present study has lifted the veil on the genetic structure of this microsatellite. By in silico analysis on the E. multilocularis genome the microsatellite was described in about 40 copies on the chromosome 5 of the parasite. Similar structure was found in the relative parasite Echinococcus granulosus, where the microsatellite was firstly described. The present study completes the first investigations made on the EmsB microsatellite origins and confirms the reliability of this highly discriminant molecular marker.

Sequence analysis of cytb gene in Echinococcus granulosus from Western China

Echinococcus granulosus is the causative agent of cystic echinococcosis with medical and veterinary importance in China. Our main objective was to discuss the genotypes and genetic diversity of E. granulosus present in domestic animals and humans in western China. A total of 45 hydatid cyst samples were collected from sheep, humans, and a yak and subjected to an analysis of the sequences of mitochondrial cytochrome b (cytb) gene. The amplified PCR product for all samples was a 1,068 bp band. The phylogenetic analysis showed that all 45 samples were identified as E. granulosus (genotype G1). Ten haplotypes were detected among the samples, with the main haplotype being H1. The haplotype diversity was 0.626, while the nucleotide diversity was 0.001. These results suggested that genetic diversity was low among our samples collected from the west of China based on cytb gene analysis. These findings may provide more information on molecular characteristics of E. granulosus from this Chinese region.

A multiplex PCR for the simultaneous detection and genotyping of the Echinococcus granulosus complex

Echinococcus granulosus is characterized by high intra-specific variability (genotypes G1–G10) and according to the new molecular phylogeny of the genus Echinococcus, the E. granulosus complex has been divided into E. granulosus sensu stricto (G1–G3), E. equinus (G4), E. ortleppi (G5), and E. canadensis (G6–G10). The molecular characterization of E. granulosus isolates is fundamental to understand the spatio-temporal epidemiology of this complex in many endemic areas with the simultaneous occurrence of different Echinococcus species and genotypes. To simplify the genotyping of the E. granulosus complex we developed a single-tube multiplex PCR (mPCR) allowing three levels of discrimination: (i) Echinococcus genus, (ii) E. granulosus complex in common, and (iii) the specific genotype within the E. granulosus complex. The methodology was established with known DNA samples of the different strains/genotypes, confirmed on 42 already genotyped samples (Spain: 22 and Bulgaria: 20) and then successfully applied on 153 unknown samples (Tunisia: 114, Algeria: 26 and Argentina: 13). The sensitivity threshold of the mPCR was found to be 5 ng Echinoccoccus DNA in a mixture of up to 1 µg of foreign DNA and the specificity was 100% when template DNA from closely related members of the genus Taenia was used. Additionally to DNA samples, the mPCR can be carried out directly on boiled hydatid fluid or on alkaline-lysed frozen or fixed protoscoleces, thus avoiding classical DNA extractions. However, when using Echinococcus eggs obtained from fecal samples of infected dogs, the sensitivity of the mPCR was low (<40%). Thus, except for copro analysis, the mPCR described here has a high potential for a worldwide application in large-scale molecular epidemiological studies on the Echinococcus genus.

The dog tapeworm Echinococcus granulosus (E. granulosus) is a cosmopolitan parasite. The adult worms reside in the small intestine of their definitive hosts (dogs). Infective eggs are shed with the feces into the environment and are orally ingested by intermediate hosts where they develop into the metacestode (larval) stage, causing cystic echinococcosis (CE) in humans and livestock. Ten intraspecific genotypes of E. granulosus (G1 to G10) have been reported from different intermediate host species. Based on the recently established molecular phylogeny, E. granulosus is now considered a complex consisting of four species: E. granulosus sensu stricto (G1/G2/G3), E. equinus (G4), E. ortleppi (G5) and E. canadensis (G6–G10). Simple and highly discriminative molecular epidemiological approaches are needed to explore dynamics, life cycle patterns, and the pathogenicity of the members of this complex. We here introduce a one-step multiplex PCR (mPCR) protocol for the genotyping and discrimination of the different members of the E. granulosus complex, allowing three levels of discrimination: (i) Echinococcus genus, (ii) E. granulosus complex, and (iii) genetic variants within the E. granulosus complex. The relatively complicated task of E. granulosus complex speciation and genotyping is clearly simplified by mPCR, and this technique therefore represents a useful tool for routine practice.

Analysis of protoscoleces-specific antigens from Echinococcus granulosus with proteomics combined with Western blot

OBJECTIVE

To establish and optimize the proteomic analysis of protoscoleces-specific antigens from Echinococcus granulosus. To provide a foundation for identifying specific antigens in the soluble proteins of E. granulosus protoscoleces for further research.

METHODS

Brood capsules were collected aseptically from fertile E. granulosus cysts from the livers of an infected patient. The fertile E. granulosus cysts were fractured, and protoscoleces were collected by centrifugation. The soluble proteins of protoscoleces were acquired using the 2D Quant kit according to the manufacturer's instructions. We employed two-dimensional electrophoresis (2-DE) combined with immunoblot assay (Western blot) to analyze the soluble components of E. granulosus protoscoleces antigens. The 2-DE and immunoblot maps obtained were analyzed with PDQuest 8.0 image analysis software.

RESULTS

About 233 soluble protein spots were identified with Coomassie-stained gels. Most of the proteins had a molecular weight of 16,000 Da to 117,000 Da, and an isoelectric point value of 3.0 to 10.0. 2-DE immunoblot was conducted and 57 specific antigen spots were observed, among which 23 spots were identified.

CONCLUSION

2-DE combined with Western blot is the key to successful proteomic analysis and presents a new possibility for searching the specific E. granulosus protoscoleces antigens.

Genotyping Echinococcus granulosus from dogs from Western Iran

Cystic echinococcosis is a zoonotic infection caused by the dog tapeworm, Echinococcus granulosus. In the present study, adults of E. granulosus (n=20) were collected from 71 dogs from Western Iran and were genetically characterized using DNA sequencing of the partial mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase 1 (nad1). Consensus sequences were obtained for cox1 (366) and nad1 (471) genes. Phylogenetic analysis of concatenated nad1 and cox1 nucleotide sequence data was performed using Bayesian Inference approach. Overall, the dog isolates indicated nine different sequences in cox1 and seven in nad1 genes. Three genotypes (G1 [75%], G2 [10%] and G3 [15%]) were identified from the isolates. The G2 sequences indicated 100% homology with reference G2 sequence in both cox1 (Genbank accession number M84662) and nad1 (AJ237633) genes. G3 sequences showed 100% homology with G3 reference sequence in nad1 (AJ237633), but displayed two different cox1 profiles, each having 99% homology with reference G3 sequence (M84663). In the phylogenetic tree all of the isolates were grouped into a distinct cluster corresponding to the G1-G3 complex with relevant reference sequences. The presence of G1 genotype (sheep strain) of E. granulosus sensu stricto as dominant genotype in dogs is emphasized. To the best of our knowledge, this study established the first record of E. granulosus sensu stricto, G2 genotype in Iran.

Morphological and molecular characterisation of Echinococcus granulosus from goat isolates in Iran

Hydatidosis is considered to be an important economic and human public health problem in Iran, where a variety of animals act as intermediate hosts. There is limited information about the genotypes of Echinococcus granulosus in goats. In this study, 20 isolates of E. granulosus obtained from goats were characterised by mitochondrial DNA sequencing and morphology of the metacestode. The mitochondrial cytochrome oxidase 1 sequences were evaluated, and the sequence analysis indicated two genotypes within the isolates. 17 samples were identified as G1 strain, and 3 isolates were identified as G6 strain. The results of the morphological studies support the findings of the molecular studies. Two types of rostellar hooks were observed in the goat isolates, in agreement with the strain identification. Type 1 hooks were morphologically similar to those of the common sheep strains, whereas the dimensions of the hooks in type 2 were similar to those normally found in the camel strain. The morphological results suggest that Echinococcus of goat origin is phenotypically similar to either the sheep (G1) or the camel (G6) strains. Further, these results suggest that the transmission of the G1 genotype between sheep and goats seems to be the predominant mode of transmission, but further work is required to verify this.

Hydatid cyst/cystic echinococcosis: anatomical and surgical nomenclature and method to quantify the cyst content solidification

The terminology related to the hydatid cyst is sometimes inappropriate and wrong designations are used, based on incorrect concepts. "Hydatid cyst" is the larval form of the tapeworms of the genus Echinococcus granulosus, a parasite found in the small intestine of carnivores. The disease, called cystic echinococcosis, is among the most neglected parasitic diseases despite the development of new drugs and other treatment modalities. Although all of us know the vital cycle of the parasite and the different aspects of the disease, the designations around the parasite, its evolution and some therapeutic procedures are not uniform. It would be useful, for all of us, to use the same nomenclature and it is absolutely necessary that the nomenclature is correct and universally accepted. In this paper I remember the correct terms related to all aspects of the hydatid cyst's nomenclature, including especially the anatomical and surgical terminology, as well as the criteria to define the cyst inactivity and the way to know when the cyst range the inactive stage after therapy.

Molecular characterization of human and animal Echinococcus granulosus isolates in Isfahan, Iran

Cystic hydatid disease (CHD) is one of the most important zoonotic diseases in different parts of Iran. While it causes major health problem, there is limited information about its transmission cycles and reservoirs of human infection. Therefore we aimed to characterize the existence Echinococcus granulosus cysts in humans and animals in the province of Isfahan, central region of Iran. We collected hydatid cysts from the liver and lungs of patients who underwent surgery procedure and also cysts were obtained from domestic animals at slaughterhouses. DNA was extracted from the protoscoleces and examined by polymerase chain reaction (PCR) of rDNA internal transcribed spacer1 (ITS1-PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP). In addition, fragments of the genes coding for mitochondrial cytochrome c oxidase subunit 1 (CO1) and NADH dehydrogenase 1 (ND1) were sequenced. Among the two different identified strains/genotypes (sheep and camel), the sheep strain was shown to be the most common genotype of E. granulosus affecting humans, sheep, cattle, goats and occasionally camels. Nine out of 26 camel samples were infected with sheep strain. However the camel genotype was observed in humans, camels and cattle. Seventeen out of 26 camel isolates, 6 out of 31 human and 5 out of 14 cattle samples were infected with the camel genotype. The camel genotypes had PCR and RFLP patterns which were different from the PCR and RFLP patterns of the rest of isolates (sheep strain). The results of this study showed that the 'camel' strain was actual source of infection to humans which circulates between intermediate hosts including camels and cattle, and it confirms the camel-dog transmission cycle in Isfahan.

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

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

[Procedure for identification of G1 genotype in Echinococcus granulosus isolates]

This study was undertaken to analyze the nucleotide sequences of a marker fragment in the mitochondrial cox1 gene in polymorphic variants of G1 strain from the nucleotide sequence bank "Genbank" and to choose conditions for a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to differentiate the G1 genotype in E.granulosus isolates. The analysis indicated that G1 genotype polymorphism was due to impact nucleotide replacements and to the varying length of the marker fragment of the coxl gene (by the presence of absence of the 5' GTGGCT 3' site with the coordinates 10275-10280). The procedure of PCR-RFLP was modified to identify the G1 variants due to the varying coxl length. New primers annealed to the variable coxl site of the following structure: 5' TGTGTTGATTTT-GCCTGG 3' (direct); 5' GCCACCACAAACCAAGTATC 3' (inverse) were chosen. Then the localizations of restriction sites were determined for the endonucleases R.Fok 1, R.Sfa NI, and R.Mael and the restriction fragment length was calculated for the RFLP analysis.

Echinococcus granulosus: biological comparison of cattle isolates from endemic regions of Argentina and Spain

In the present study we have compared cattle isolates of Echinococcus granulosus from Argentina and Spain. The aim was to compare and determine if there exist phenotypic and genetic differences within E. granulosus cattle isolates between an endemic area of Spain (where the disease is mainly restricted to a sheep-dog cycle) and an endemic area of Argentina (where cattle are the most abundant intermediate hosts). The Spanish samples were previously identified as G1 genotype. The Argentinean samples were also identified as G1, but some variants were found for the cytochrome c oxidase-1 (CO1) and NADH dehydrogenase-1 (ND1) mitochondrial genes. When comparing the cyst features and the morphology of the larval rostellar hooks in both regions, some differences were found. The morphometric analyses of the larval rostellar hooks showed the existence of two distinct clearly separated groups (one corresponding to the Argentinean samples and the other to the Spanish ones). In conclusion, there are some genetic and phenotypic differences within E. granulosus cattle isolates from Argentina and Spain. Probably these differences, more important from an epidemiological point of view, are related to different steps in the disease control in both countries. Further studies involving other epidemiological, morphometric and molecular data, including other types of livestock, would contribute to clarify and expand the present work.

Polymorphism and natural selection of antigen B1 of Echinococcus granulosus isolated from different host assemblages in India

Antigen B (AgB) is an excretory-secretory product of larval stage of Echinococcus granulosus. This antigen is abundantly secreted by larval stage of the worm. AgB is encoded by a multigene family and is suggested to be involved in evasion of host immune system. During the present study a total of 110 animal isolates of E. granulosus has been screened by mutation scan screening. A total of 14 conformers were detected on the basis of single strand banding profile of 129 bp fragment of AgB1 subunit. Analysis of sequence information of 14 conformers could cluster the isolates into two different group viz. buffalo-cattle and sheep-goat cluster. Conceptual amino acid sequence information of two clusters could be differentiated in terms of MHCII binding propensity of agretope and B-cell epitope region. This type of analysis of clustering of animal isolates on the basis of binding propensity towards different MHC antigens and B-cell linear epitope is the example of its own kind. Positive Tajima's D value indicated that, AgB1 is under balancing selection pressure which might be considered as heterogeneous selection pressure exerted by the host.

Echinococcus granulosus infection and options for control of cystic echinococcosis in Tibetan communities of Western Sichuan Province, China

Background

Human cystic echinococcosis (CE) is highly endemic in the Tibetan regions of Sichuan where most families keep guard dogs and where there are considerable numbers of ownerless/stray dogs. Strong Buddhist beliefs do not allow for elimination of stray dogs, and many strays are actually fed and adopted by households or monasteries. On account of the high altitude (3900–5000 m), pasturage is the major agricultural activity in this area. The harsh mountainous climate often leads to many grazing animals dying on the pasture at the end of a hard winter. The skin and some meat are taken, and the rest of the animal is left for scavenging birds and animals. The poor sanitation and hygiene, the Buddhist doctrine of allowing old livestock to die naturally, plus the unrestricted disposal of animal viscera post-slaughter may be responsible for the high prevalence of human CE in this setting.

Methods and Findings

As part of a large collaborative control program for CE in Ganzi County, situated in the west of Sichuan Province, surveillance for Echinococcus infection in domestic dogs using a coproantigen method and necropsy of unwanted dogs was carried out prior to (in 2000) and after (in 2005) dog anthelminthic treatment (5 mg/kg oral praziquantal at 6 month intervals) to determine the efficacy of the treatment for control. The prevalence of E. granulosus only in dogs by necropsy was 27% and 22%, and prevalence of both Echinococcus spp. by necropsy was 63% and 38%; prevalence of both Echinococcus spp. by coproantigen analysis was 50% and 17%. Necropsy of sheep/goats (age <1 to 12 years) (prevalence of E. granulosus in 1–6-year-old animals was 38% and in 10–12-year-old animals was 70%) and yaks (age 4 years) (prevalence of E. granulosus was 38%) was undertaken to determine the baseline transmission pressure. Protoscoleces were only found in very old sheep/goats and yaks. Necropsy of dogs in the Datangma district indicated that there was no apparent significant change in the overall prevalence of E. granulosus in unwanted dogs after 5 years of 6-month praziquantel treatment. However, this was likely due to the number of dogs available for necropsy being too small to reflect the real situation prevailing. There was a highly significant decrease in Echinococcus prevalence after the 5-year treatment program shown by coproantigen-ELISA. This indicated a decreasing but continuing risk for re-infection of domestic and stray dogs. Genotyping of E. granulosus samples obtained from necropsied sheep/goats and yaks and from locally infected humans at surgery was carried out to determine the strain of parasite responsible for human infection. DNA genotyping indicated that only the sheep strain (G1) of E. granulosus was present in the study area.

Conclusions

Considerable re-infection rates of E. granulosus among dogs indicated a high infection pressure from infected livestock in this region, most likely from older animals dying on the pasture. A combination of livestock vaccination with the Eg95 vaccine, which is effective against the sheep strain of E. granulosus, and dog anthelmintic treatment, thus targeting two critical points of the parasite life-cycle, would avoid the conflicts of religion or local culture and could achieve the goal of hydatid control in the long term.

Human cystic echinococcosis (CE) is highly endemic in Tibetan regions of Sichuan. As part of a control program for CE in Datangma district, Ganzi County, necropsy of strays and coproantigen-ELISA of all dogs was carried out prior to and post-drug treatment to determine the efficacy of the treatment for control. Examination of sheep/goats and yaks was undertaken to determine the baseline transmission pressure to dogs. The necropsy results indicated no apparent significant change in the overall prevalence of E. granulosus in unwanted dogs after 5 years of 6-month treatment. In contrast, there was a highly significant decrease in Echinococcus prevalence in domestic/stray dogs after the 5-year treatment program shown by coproantigen-ELISA. This indicated a decreasing but continuing risk for re-infection of dogs resulting from high infection pressure from the numerous infected domestic animals. DNA genotyping indicated the presence only of the sheep strain (G1) of E. granulosus in the study area. A combination of livestock vaccination with the highly effective Eg95 vaccine and dog drug treatment, targeting two critical points of the parasite life-cycle, would avoid the conflicts of religion or local culture and achieve the goal of hydatid control in the long term in the area.

Human hydatid disease in Peru is basically restricted to Echinococcus granulosus genotype G1

A molecular PCR study using DNA from 21 hydatid cysts was performed to determine which strain type is responsible for human infection in Peru. The mitochondrial cytochrome c oxidase subunit 1 (CO1) gene was amplified in 20 out of 21 samples, revealing that all but 1 sample (19/20, 95%) belonged to the common sheep strain (G1). The remaining samples belonged to the camel strain (G6). The G1 genotype was most frequently found in human cases of cystic hydatid disease (CHD) in Peru. Local control measures should focus primarily on decreasing dog and sheep infection rather than intermediate reservoirs.

[Associations of the genotypes of the CYP1A1 gene with predisposition to hydatid disease caused by Echinococcus granulosus strain G1]

DNA samples isolated from peripheral venous blood lymphocytes in 73 children with hydatid disease were studied. The polymorphism of exon 7 (A4889G) of the CYP1A1 gene was analyzed by polymerase chain reaction, followed by hydrolysis with restriction endonuclease HincII. The material for E. granulosus genotypes to be studied was obtained from the germinal layer of larvocysts. The fragment of the mitochondrial gene encoding for the first subunit of cytochome-C-oxidase was as a DNA marker. The amplified E. granulosus DNA fragments underwent direct sequencing and a genotype was identified. The findings have led to the conclusion that carriage of polymorphic allele Val of exon 7 (A4889G) of the CYP1A1 gene in those infested with E. granulosus genotype G1 (common, sheep strain) is a risk factor of the development of the clinical form of echinococcosis granulosus.

Echinococcus granulosus antigen B gene family: Further studies of strain polymorphism at the genomic and transcriptional levels

Echinococcus granulosus AgB gene family is constituted by five gene loci. In a previous study, we analyzed the strain variation of EgAgB2/B4 sequences. Here, we have analyzed, by SSCP and sequencing, 250 genomic clones of EgAgB1/B3/B5 gene cluster from five E. granulosus strains. Several new EgAgB genomic variants were found. EgAgB1 and EgAgB3 genomic sequences grouped E. granulosus strains by phylogenetic tools in two clusters: one formed by G1/G2 and the other by G5, G6/G7 strains, in accordance with other molecular markers. EgAgB5 genomic and cDNA sequences were only found in G1/G2 cluster. Reverse transcription-PCR analysis using subunit specific primers revealed that all the EgAgB genes were transcribed in G1 and G7 strains with the exception of EgAgB5 transcripts that were not detected in G7 strain. Interestingly, AgB2 transcripts that were probably processed by an aberrant splicing mechanism leading to a non-functional B2 protein were found in G7 strain.

Molecular characterization of Echinococcus granulosus in Tunisia and Mauritania by mitochondrial rrnS gene sequencing

Cystic hydatid disease is a zoonotic parasitic disease caused by the cestode Echinococcus granulosus and represents a major public health problem in many countries around the world, including North Africa. E. granulosus exists as a series of genetic variants or strains which differ in a wide variety of criteria that impact on the epidemiology, pathology and control of cystic hydatid disease. Nucleotide sequencing of the mitochondrial rrnS gene was here used to characterize 38 E. granulosus isolates collected from different regions and hosts in Tunisia and Mauritania. The results obtained reveal a significant genetic differentiation between E. granulosus hydatid cysts identified as belonging to the G1 genotype and to the G6/G7 cluster using the rrnS gene as marker, and indicate the circulation of the common sheep strain (G1) in all host species from Tunisia and the camel/pig strain cluster (G6/G7) in camel from Mauritania. Other investigations, using this method, are necessary for further genetic analysis of a wider range of isolates from different host species in order to more fully understand the genetic structure of E. granulosus populations and their transmission dynamics in this and neighbouring African countries.

Molecular characterization of a novel gene encoding an 8-kDa-subunit of antigen B from Echinococcus granulosus genotypes 1 and 6

Antigen B in hydatid cyst fluid of Echinococcus granulosus is a polymeric lipoprotein of 160 kDa, and is an aggregate of several different but homologous small proteins with approximately 8 kDa which are encoded by a multigene family. Four genes encoding 8-kDa-subunit monomers of the antigen B have been identified from E. granulosus. Recently, we have isolated another novel gene from Echinococcus multilocularis encoding a fifth 8-kDa-subunit of AgB (named EmAgB8/5), predominantly transcribed in the adult worm, but not in vesicles of metacestodes. In this study, we cloned and characterized two EmAgB8/5 homologue genes from E. granulosus genotypes 1 and 6 by PCR, and named as EgG1AgB8/5 and EgG6AgB8/5, respectively. The phylogenetic relationship of these genes with other genes encoding the antigen B 8-kDa-subunit monomers was also discussed.

Occurrence of the G3 Indian buffalo strain of Echinococcus granulosus in cattle

During a survey carried out to define the occurrence of Echinococcus granulosus in cattle bred in the province of Rieti (Central Italy), molecular diagnostics (PCR amplification and sequencing of a partial region of the mitochondrial CO1 gene) showed that 6/10 positive bovines harboured hydatid cysts (No.=16) genetically identical (95.8-100%) to the Indian buffalo genotype G3. As far the location of the 16 cysts, 11 of them were found in the lungs of three animals, whereas 5 cysts were in the liver of three parasitized hosts. The occurrence of genotype G3 in 60% of parasitized bovines living in an area never studied before provides more definite evidence about the existence of the strain in this region, and proves that cattle have to be considered a non-accidental host.

[Identification of the causative agent of echinococcosis in the population of the South Urals]

The topicality of the problem associated with echinococcosis granulosus in the South Urals is determined by its wide spread and a considerable economic damage made to this region by this invasion. The study was undertaken to reveal the intraspecific affiliation of Echinococcus granulosus that induces hydatid disease in the population of the South Urals. Samples for studies were taken from the fertile larval cysts obtained during intraoperative intervention in patients with hydatid disease. As morphological criteria for differentiation, the authors examined the proboscis uncuses of protoscolexes. For E. granulosus genomic typing, polymerase chain reaction (PCR) of DNA synthesis was used, as described by Gasser (1998). As a DNA marker, the authors used a fragment of the mitochondrial gene encoding for the first subunit of cytochome-C-oxidase. The DNA fragments obtained by PCR from 9 isolated underwent the direct enzyme dideoxy-sequencing test (Senger, 1977). As a result, the causative agent of echinococcosis granulosis was first identified in the patient of the South Urals. In children and adults, the clinical form of the disease is caused by E. granulosus with the genotype G - common, that of domestic sheep. Comparative analysis of molecular data revealed the presence of genotype G1 variations circulating in the South Urals homologous to the sequences recorded in the GenBank under numbers U50464 and DQ109036.

Echinococcus granulosus from Mexican pigs is the same strain as that in Polish pigs

Samples of Echinococcus granulosus from seven pigs from Mexico were compared with isolates of the parasite from pigs in Poland and representative strains and species of Echinococcus. Isolates from pigs in Mexico were found to be genetically identical to E. granulosus from Polish pigs and distinct from other major genotypes by sequencing part of the mitochondrial cytochrome c oxidase I (COI) mtDNA locus, restriction fragment length polymorphism (RFLP) of the polymerase chain reaction (PCR) amplified rDNA internal transcribed spacer (ITS) 1 using five different enzymes, and random amplified polymorphic DNA (RAPD) analysis. These results were complemented by data on hook morphology and together strengthen the view that Echinococcus maintained in a cycle involving pigs and dogs is a distinct strain that is conserved genetically in different geographical areas. The present study supports the close relationship of the cervid, camel and pig strains and raises the question of their taxonomic status.

Molecular characterization of Echinococcus granulosus in sheep and goats of Peloponnesus, Greece

Although cystic echinococcosis (CE) has been a recognized public health problem in Greece, molecular data are lacking regarding the types and prevalences of infecting strains of the etiological agent Echinococcus granulosus. Therefore, we investigated the prevalence of CE and determined the infecting genotypes in sheep and goats in Peloponnesus, a large region of southern Greece. Liver and lung samples were obtained from 210 sheep and 190 goats slaughtered between January and December 2005, and the number, morphology, and fertility of hydatid cysts were determined. Protoscoleces or germinal layers were collected from individual cysts (20 sheep and 20 goats), and DNA was extracted. A polymerase chain reaction (PCR)/seminested PCR system was used to distinguish the G1, G5, and G6/G7 strains, and a specific molecular diagnosis was obtained by sequencing PCR-amplified mitochondrial DNA encoding cytochrome c oxidase subunit 1 and NADH dehydrogenase I genes. The prevalence of CE was 30.4% in sheep and 14.7% in goats; fertile cysts were found in 16.2 and 7.4%, respectively. Overall, 18 of 20 sheep harbored the G1 genotype (common sheep strain), while the remaining two animals had the G3 (buffalo) strain. All 20 goats were infected with the G7 (pig) strain. These results document the prevalence of E. granulosus infection in food animals in this geographical area and reveal for the first time the presence of, at least, three parasite genotypes.

Genotypic characterisation of Indian cattle, buffalo and sheep isolates of Echinococcus granulosus

Twelve isolates of Echinococcus granulosus, collected from domestic animals, including cattle, buffalo and sheep were analysed for DNA nucleotide sequence variation within mitochondrial cytochrome c oxidase I (coxI), NADH dehydrogenase subunit I (nadI) and internal transcribed spacer gene I (ITS1). After analysis of sequence information this was found that the fragment size of ITS1 of buffalo isolate was more in comparison to cattle and sheep isolates. Based on the nadI genotype this was found that Indian cattle, buffalo and sheep isolates could be grouped into E. granulosus sensu stricto. Based on coxI genotype two sheep isolates and one buffalo isolate were homologous to G2 genotype. Rests of the isolates were microvariants of G2 genotype. Presence of G2 genotype in buffalo is the first report of this genotype from this host.

Taxonomic position and geographical distribution of the common sheep G1 and camel G6 strains of Echinococcus granulosus in three African countries

The taxonomic and phylogenetic status of Echinococcus granulosus strains are still controversial and under discussion. In the present study, we investigated the genetic polymorphism of E. granulosus isolates originating from three countries of Africa, including a region of Algeria, where the common G1 sheep and the camel G6 strains coexist sympatrically. Seventy-one hydatid cysts were collected from sheep, cattle, camels, and humans. Two mitochondrial markers (cox1 and nad1) were used for strain identification. Two nuclear markers (actII and hbx2) were used to study the possible occurrence of cross-fertilization. Despite the heterogeneity observed among the G1 isolates, they were all localized within one robust cluster. A second strong cluster was also observed containing all of the G6 isolates. Both strains appeared as two distinct groups, and no cases of interbreeding were found. Thus, the attribution of a species rank can be suggested. We also found the Tasmanian sheep G2 strain for the first time in Africa. Because of the slight variations observed between the common sheep and the Tasmanian sheep strains, further studies should be carried out to elucidate the epidemiological relevance of this genetic discrimination.

Genetic differences between Tunisian camel and sheep strains of the cestodeEchinococcus granulosusrevealed by SSCP

Ovine and dromedary Echinococcus granulosus isolates from Tunisia were identified as G1 and G6 strains based on polymorphism of the mitochondrial cytochrome C oxydase CO1. Single strand conformation polymorphism (SSCP) was used in order to examine the genetic variation within and between Tunisian G1 and G6 strains and to estimate the extent of selfing. The dromedary isolates are genetically distinct from sheep isolates (high value of genetic variation between populations: Fst= 0.46). No significant deficiency in heterozygotes was found in sheep isolates, whereas heterozygote deficiency (suggesting selfing) was found in a limited number of camel isolates.

Echinococcus granulosus (Cestoda, Taeniidae) in the Iberian wolf

The intestinal contents of 27 Iberian wolves (Canis lupus signatus) from Spain were screened for the presence of the taenid cestode Echinococcus granulosus. Four animals were found positive (15% prevalence). The intensity of parasitation was variable (mean 71, range 1-147 E. granulosus per host). Gravid individuals were found in all wolves positive with the parasite. Molecular characterization of the parasite material showed that the wolf strain belongs to the G1 genotype. According to the results, we conclude that the Iberian wolf takes part in the maintenance of the life cycle of this zoonotic parasite in Spain and that this fact could have public health relevance.

Epidemiological surveillance of ovine hydatidosis in Tierra del Fuego, Patagonia Argentina, 1997–1999

Cystic echinococcosis is the most prevalent zoonosis in Tierra del Fuego province, Argentina, with important economic, productive and public health consequences. The present work was performed to determine the ovine prevalence in Tierra del Fuego, Argentina, as well as to evaluate the quality of diagnostic systems in slaughterhouses. Moreover, genetic analyses to characterize the strain of Echinococcus granulosus involved in the region were done. The first actions to perform a diagnosis of the epidemiological situation of hydatidosis in Tierra del Fuego were done between 1976 and 1977. A canine prevalence of 80% and an ovine prevalence of 55% results were obtained. Since 1979 the control program of Hydatidosis of Tierra del Fuego was implemented. It was based on semiannual canine anthelmintic treatment with praziquantel at dose of 5mg/kg, and complemented with sanitary education and canine and ovine epidemiological surveillance. During May 1997-January 1999: 5,916 sheep coming from 20 farms of the programmatic area were evaluated. In the lamb category, hydatid cysts were not found. In the adults category, 62 infected animals were found (3.2%). The ovine prevalence was 1.1% and there was 100% of coincidence between diagnosis in the slaughterhouse, re-inspection in the laboratory and histopathological study. The marked decrease in the prevalence observed for sheep infection evidenced a destabilization of the biological cycle of the parasite. This could be explained by the application of a control program with uninterrupted systematic actions. Polymerase chain reaction-ribosomal ITS-1 DNA (rDNA) restriction fragment length polymorphism (PCR-RFLP) analysis and partial sequencing of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene were used to characterize E. granulosus isolates collected from different regions of Tierra del Fuego to determine which genotypes occurred in this region. The results revealed the presence of the G1 genotype (sheep-dog strain). This is the first time that a molecular analysis was performed for the E. granulosus isolates from Tierra del Fuego.

Morphological and molecular characteristics of Echinococcus multilocularis and Echinococcus granulosus mixed infection in a dog from Xinjiang, China

The Xinjiang plateau of western China has been shown to have a high prevalence for human cystic echinococcosis (CE) caused by Echinococcus granulosus, and human alveolar echinococcosis (AE) caused by Echinococcus multilocularis. The domestic dog is suspected to be the primary definitive host for the transmission of both E. granulosus and E. multilocularis to humans in this locality. Seventeen of 30 stray dogs from Hejing County of Xinjiang were found positive for E. granulosus post mortem, and one double infection was suspected. Worm samples were collected, dyed by carmine, and observed microscopically. Carmine staining examination clearly revealed the differences in number of proglottids and appearance of uterine branches and lateral genital pore for those two species of Echinococcus. Furthermore, gene target DNA fragments were amplified for formal identification of the two parasite species, based on 12s rRNA mitochondrial gene. The PCR products were purified and sequenced. Compared with NCBI GenBank, the DNA sequences demonstrated 100% identity with E. granulosus (sheep strain, G1 genotype) and E. multilocularis.

Molecular study of Echinococcus in west-central China

West-central China is an important endemic focus of both alveolar and cystic echinococcosis where several species of intermediate host are commonly infected with Echinococcus granulosus and E. multilocularis . Isolates of E. granulosus were collected from humans and other animals from different geographical areas of Qinghai, Ningxia, Gansu and Sichuan, and genotyped using the mitochondrial DNA marker ATP synthase subunit 6 gene (atp6). The sheep strain (G1 genotype) of E. granulosus was shown to be the only genotype present in sheep, cattle, goats, yaks and humans in the study areas. However, some heterogeneity in the atp6 sequence was evident in a number of the isolates with the most frequent change being a silent substitution (G/A) at position 360 compared with the G1 reference sequence representing isolates collected from the majority of hosts except humans. Two E. multilocularis isolates examined also had sequences that varied from each other and from the reference E. multilocularis atp6 sequence. The genotypic variation we report may reflect phenotypic differences with important consequences in terms of increased host infectivity for hosts by local Echinococcus strains, possibly impacting on the epidemiology and control of echinococcosis. Such adaptations may also result in different sensitivity to drugs or increased virulence for hosts that will impede control efforts and even affect vaccination strategies against Echinococcus.

Present situation of echinococcosis in the Middle East and Arabic North Africa

Echinococcosis is one of the major zoonotic parasitic diseases in the Middle East and Arabic North Africa from Morocco to Egypt. Both cystic and alveolar echinococcosis has been reported from these areas. However, cystic echinococcosis is more prevalent and has been reported from all countries in the Middle East and Arabic North Africa. Alveolar echinococcosis is less prevalent and has been reported only from Iran, Turkey, Iraq and Tunisia. Present situation of echinococcosis in dogs and other definitive hosts, animal intermediate hosts and humans in the Middle East and Arabic North Africa has been reviewed. Echinococcus granulosus is highly prevalent in Iran, Turkey, Iraq, Morocco, Tunisia, and Libya. In the Levant countries, the cystic echinococcosis is also highly endemic. In Oman, it is endemic with low prevalence and a very low level in Cyprus. Various surveys have indicated that hydatid cysts are commonly found in sheep, cattle, goats and camels throughout the Middle East and Arabic North Africa. Sheep are the most infected animals of these regions. Most of studies on human have been focused on surgical reports although several population studies have been performed using serological and imaging techniques. Human cystic echinococcosis (CE) is prevalent in the Middle East and Arabic North Africa. It is hyper endemic in Iran, Turkey, Iraq, Jordan, Morocco, Libya, Tunisia, and Algeria, and endemic in Egypt. Studies on the strain specificities of E. granulosus in the Middle East revealed sheep strain (G1) present in sheep, goats, cattle, camels and humans, and the camel strain (G6) in camels, sheep, cattle as well as humans. Dog/sheep strain seems to be more prevalent in the foregoing regions in documented reports from Iran and Jordan. However, a strain of E. granulosus, which resembles the horse strain (G4) strain, has been reported from Jordan. Strain specifications of E. granulosus in Arabic North Africa showed that sheep/dog strain (G1) have been reported from Tunisia and Libya both from humans and animals. However, in Egypt the human cases reported are of camel/dog strain.

Genetic typing of Echinococcus granulosus in Romania

In Romania, cystic echinococcosis is endemic and affects, besides humans, various animal species including sheep, cattle, and swine. As yet, no molecular-genetic typing has been carried out to clearly identify the putative strains being transmitted there. Parasite samples (protoscoleces or germinal layers) were collected from infected intermediate hosts and subsequently analyzed by comparing the PCR-amplified DNA sequences of three targets: one nuclear (BG1/3) and two mitochondrial (cox1 and nadI). Three strains were identified with the mitochondrial sequences: (i) the common sheep strain (G1) which circulates between sheep and cattle and is infective for humans, (ii) the Tasmanian sheep strain (G2) infecting sheep and cattle, and (iii) the pig strain (G7) predominantly found in swine. To our knowledge, this is the first report which demonstrates the occurrence of the Tasmanian sheep strain in cattle and the sympatric occurrence of these three strains (G1, G2, and G7) in Europe.

Molecular evidence of ovine (G1) and camel (G6) strains of Echinococcus granulosus in Tunisia and putative role of cattle in human contamination

Three hundred and seventy-two cysts coming from 50 humans, 166 cattle, 153 sheep and 3 camels were collected in order to establish some epidemiological molecular information in Tunisia for the first time. The analysis by PCR-RFLP of ITS1 sequence showed that all the human, ovine and bovine cysts were due to the common sheep strain of Echinococcus granulosus. The sequencing of the CO1 gene of 37 isolates confirm the G1 genotype of this strain. For seven of these isolates, we found the mutation C56T which is present in the three principal intermediate hosts: human (three cysts), cattle (three cysts) and sheep (one cyst). With regard to the G1 genotype, we identified three other point mutations. The camel strain G6 is uniquely found in the three camels isolates and not in the other intermediate hosts analysed. The fertility of the bovine cyst represents 48% that means that this host is involved in a bovine-dog cycle and consequently represents a reservoir of sheep strain in Tunisia. Our results confirm the importance of the prophylaxis measures in order to disrupt the cycle of transmission sheep-dog in Tunisia. Nevertheless, the supervision of bovine infection should be reinforced because this intermediate host may constitute an important link with the human contamination.

Strain characterization of Echinococcus granulosus protoscoleces of cattle origin using the in vitro vesicular development

The aim of this work was to characterize the strain of protoscoleces of E. granulosus of cattle origin using the in vitro vesicular development. The in vitro development of these samples was compared to samples of sheep origin determined previously by genetic analyses as common sheep strain (G1). There were similarities between sheep and cattle samples not only in the time of microcysts formation, but also in the development process. Vesiculated protoscoleces and protoscoleces with posterior bladders appeared during the first week of incubation. After 14 days of culture, a laminated layer appeared like a fine membrane in one of the extremes of the protoscoleces. In the sheep samples, microcysts were observed between 19 and 20 days. In the cattle samples, microcysts appeared between 20 and 23 days. The coincidence between the development times and physiological characteristics found in the present study may indicate that the parasites from cattle and sheep were of the same strain.

Echinococcus granulosus cattle strain identification in an autochthonous case of cystic echinococcosis in central Mexico

Echinococcosis is a frequent hepatic parasitic disease in several countries but it is practically absent in Mexico. A cattle strain of Echinococcus granulosus was identified by RAPD, PCR-RFLP and mitochondrial CO1 gene analysis in an autochthonous case. The parasite was obtained after a laparoscopic excision of a liver cyst from a patient that was symptomatic for 6 years but mis-diagnosed before hospitalization.