Characterization of Echinococcus granulosus isolates from human, sheep and camel in Iran

Genetic diversity and haplotypes of Echinococcus granulosus isolated from cattle and buffaloes and first report of E. ortleppi (G5) in buffaloes in Pakistan based on mitochondrial cytochrome c oxidase subunit-1 gene (mt-CO1) markers

Cystic echinococcosis (CE) is a parasitic disease that is caused by larval stage of Echinococcus granulosus tapeworm, one of the most important and neglected zoonotic disease. Although the echinococcosis is endemic in the neighboring countries, information regarding circulating genotypes of E. granulosus sensu lato is scarce in Pakistan. Therefore, the main purpose of this report was to contribute in molecular epidemiology and to find genetic variation and haplotypes of E. granulosus s.l. in cattle and buffalo isolates. To identify species circulating in country, parasite samples were collected from different slaughterhouses and butcher shops of two major cities, Rawalpindi and Peshawar located in Punjab and Khyber Pakhtunkhwa (KP) provinces, Pakistan, respectively. A total of 100 CE cyst samples were investigated from buffalo (n = 61), and cattle (n = 39) hosts. After genomic DNA extraction from individual cyst materials, mt-CO1 (875 bp) gene was amplified by PCR. After that, PCR products were electrophoresed on the agarose gel then purified and sequenced using forward primer. The sequences were trimmed (779 bp), aligned and matched with NCBI published sequences. E. granulosus s.s. (G1, G3) (71.4%; n = 20/28) was confirmed as the dominant species in buffalo and cattle. E. ortleppi (G5) (28.6%; n = 8/28) was recorded for the first time in both buffalo and cattle isolates from Rawalpindi. E. granulosus s.l. haplotype network showed single predominant haplotype, which comprised 40% of population. Tajima's D and Fu's Fs were negative and significant for E. ortleppi (G5), suggesting population expansion in Pakistan. Therefore, more studies using isolates of E. granulosus s.l. from various locations and intermediate hosts across Pakistan will add new data on molecular epidemiology and genotyping for effective control strategies of CE in Pakistan.

Report of a two-headed protoscolex of Echinococcus granulosus revealed by phase contrast microscopy in Shiraz, Iran

Echinococcus granulosus sensu lato can produce cystic echinococcosis (CE)/hydatidosis in different hosts. Each CE cyst can produce numerous protoscoleces by its germinal layer in two forms: evaginated and invaginated. Usually, each protoscolex has one head consisting of a rostellum with two rows of hooks and four suckers. During a study of protoscolicidal agents on sheep Echinococcus granulosus protoscoleces, and investigations on their microscopic changes using Phase contrast microscopy, we observed a case of two- headed evaginated protoscolex. Two heads were attached to a unique bigger size of protoscolex body. Morphological observations showed its dimension around two times of usual protoscolex. There was no space between the bodies, hence one fused body was observed which was clearly shown by Phase contrast microscopy. Each head possessed two rows of hooks. Using micrometry all parts of the two-headed protoscolex, especially hooks were measured and photographed showing all aspects of its morphology including tegument, hooks, and two heads. Specific parts of two-headed protoscolex including suckers, hooks, also calcareous corpuscles were measured. The measurements on the two-headed protoscolex showed that the small hook blade length (SBL) and large hook blade length (LBL) were almost langer than one head protoscolex. A total of 120 calcareous corpuscles in two headed-protoscolex is much higher than one head protoscoleces.

Occurrence and genetic characterization of Echinococcus granulosus sensu lato from domestic animals in Central Iran

Background

The species complex of Echinococcus granulosus sensu lato (s.l.) causes cystic echinococcosis distributed worldwide. There is no genotype information from hydatid cysts in the intermediate hosts in Central Iran. Therefore, in this study, we analyzed the hydatid cysts in livestock slaughtered in an abattoir in this region. Six hundred fifty-seven hydatid cysts were isolated from 97 animals, including sheep, cattle, camels, and goats slaughtered in Yazd abattoir from September 2018 to January 2020. The demographic data was collected as well as cyst location, fertility, and viability. Out of 657 samples, 164 samples were genotyped. Then, phylogenetic analysis was performed using MEGAX. Statistical analyses were done using SPSS version 16.0 by chi-square with a significant difference of less than 0.05.

Results

Out of 164 samples, the G1-G3 complex genotype had the most frequency in samples, with 135 cases recognized. The G6/G7 was observed in 19 isolates and G5 was reported in nine samples. One sample was detected as Taenia hydatigena.

Conclusions

This study showed that G1-G3 and G6/G7 genotypes were presented in all animals, but G5 was reported only in cattle, goats, and camels. It is the first molecular identification of cystic echinococcosis in Central Iran. Hence, reporting G5 in livestock in this area should be considered due to transmission to humans.

Prevalence and Molecular Characterization of Cystic Echinococcosis in Livestock Population of the Malakand Division, Khyber Pakhtunkhwa, Pakistan

Cystic echinococcosis (CE) is a neglected zoonotic disease prevalent in Pakistan, but the genetic diversity of the cestode is largely unexplored in the country. This study investigated the molecular epidemiology of CE infecting the livestock population of the Malakand division, Khyber Pakhtunkhwa, Pakistan. A total of 1,200 livestock, including buffaloes, cattle, goats, and sheep, were examined for echinococcosis from November 2017-2018 at different slaughterhouses in the Malakand division. Hydatid cysts were collected from different organs, and hydatid cyst fluid (HCF) was examined microscopically and used for DNA extraction. The LSU (rrnl) and NAD1 genes were amplified and sequenced. The overall prevalence of CE was 17% (204/1,200), including cows (21.7%), buffaloes (17.4%), goats (10%), and sheep (9.6%). The infection was relatively more prevalent among males (17%) than females (16.9%) and animals of older age (>5 years) (p = 0.710). Liver (63.2%) and lungs (25%) were more affected as compared to kidneys (6.8%) and heart (4.9%). HCF analysis indicated that 52.0% of the cysts were sterile and (48.0%) were fertile. Sequencing and phylogenetic analyses confirmed 80.0% of the isolates as Echinococcus granulosus sensu stricto (G1-G3) in all animal species, while Echinococcus equinus (G4) and Echinococcus ortleppi (G5) were present in buffaloes. The present study concluded that CE is prevalent in the livestock population of Malakand. Besides E. granulosus s. s. (G1-G3), E. ortleppi genotype (G5) and E. equinus (G4) in livestock were also reported.

The Molecular Epidemiology of Cystic and Alveolar Echinococcosis in Southeast Turkey

Background

The migration of humans and climatic and environmental changes cause the emergence of infectious diseases. This study aimed to investigate the changes in the molecular epidemiology of the echinococcosis in the southeast region of Turkey after migrations.

Methods

Overall, 159 tissues samples were taken from suspected cases of echinococcosis at the Kilis State Hospital in the southeast region of Turkey. All of the tissues samples were analyzed using histopathology methods, PCR, Real-time PCR methods, DNA sequencing, and phylogenetic analyses in laboratories.

Results

The positivity values of the histopathology, the polymerase chain reaction, and the Real-time PCR methods were found to be 14.5% (23/159),15.7% (25/159), and 16.9% (27/159), respectively. 32.0 % (8/25) E. multilocularis of Echinococcus isolates and 68% (17/25) E. granulosus of Echinococcus isolates were identified using PCR methods. 58.8% (10/17) of the E. granulosus isolates were found to be Genotype 1% and 41.2% (7/17) E. granulosus isolates were found to be Genotype 3.

Conclusion

Molecular methods play an important role in the epidemiology, treatment, and diagnosis of diseases. Increasing immigration in a geographical area may create social, economic, and health problems in that area. For this reason, epidemiological studies of infectious diseases should be updated in areas with immigration.

Echinococcoses in Iran, Turkey, and Pakistan: Old Diseases in the New Millennium

Echinococcosis is considered a cosmopolitan zoonosis caused by different species of small taeniid tapeworms of the genus Echinococcus and is regarded as a neglected zoonosis. Cystic and alveolar echinococcoses are endemic diseases of Tibetan, Pamir, and Iranian plateaus. All of the countries within the Iranian plateau are affected by echinococcosis. Pakistan, Turkey, and Iran are the three most populous countries of the region, in which echinococcosis is highly endemic. The three neighboring countries share strong cultural and socioeconomic ties. The present study aimed to provide a broad review of the status of cystic and alveolar echinococcosis, summarizing the current knowledge about geographical distribution, molecular epidemiology, and transmission dynamics of Echinococcus granulosus sensu lato and Echinococcus multilocularis in this region. Additionally, we aimed to understand disease burden and risk factors as basic requirements for establishing a surveillance system and planning prevention and control programs. A considerable body of information is available on different aspects of echinococcosis in this region; however, several information and research gaps need to be filled before planning control programs. None of the countries in the region have an elaborate echinococcosis control program. Effective control programs require multi/intersectoral coordination within a One Health approach with a long-term political and administrative commitment and enhanced international collaboration among the three countries.

Cystic echinococcosis: an emerging zoonosis in southern regions of Khyber Pakhtunkhwa, Pakistan

Background

Cystic echinococcosis (CE) is one of the principal causes of economic loss to the livestock industry because of its morbidity and mortality of food-producing animals and condemnation of important visceral organs. Pakistan being an agricultural country having an extensive livestock sector, is mostly practiced by poor people, which has a fundamental role in the economy. The present study was aimed to conduct a cross-sectional survey and PCR based confirmation of Echinococcus granulosus in sheep, goats, cows, and buffaloes from southern regions (three districts: Lakki Marwat, Bannu, and Karak) of Khyber Pakhtunkhwa, Pakistan. During the study, a total of 2833 animals were examined randomly including; sheep (n = 529), goats (n = 428), cows (n = 1693), and buffaloes (n = 183). Hydatid cysts were collected and examined for the presence of protoscoleces using microscopy. Detection of DNA was performed by using PCR and two mitochondrial genetic markers namely; NAD-1 and COX-1 were amplified.

Results

The overall prevalence of CE was found to be (9%) among the examined animals. The hydatid cyst infection was highly prevalent in buffaloes (12%), followed by sheep (10%), cows (9%), and goats (5.1%). Cystic echinococcosis was more prevalent (10%; 96/992) in district Lakki Marwat followed by district Bannu (9%; 112/1246) and Karak (7%; 39/595). Female animals were more likely to be infected with CE (11.6%) than male animals (5.3%) (p = 0.001). Similarly, the infection was higher in the older group of animals as compared to younger (p = 0.001). Mostly (52.2%; n = 129) of hydatid cysts were found in the liver, while (64.4%; n = 159) cysts of the infected animals were infertile. PCR based identification confirmed the presence of E. granulosus sensu stricto (s.s) in the study area.

Conclusion

Cystic echinococcosis was found to be highly prevalent in southern regions of Khyber Pakhtunkhwa and could be a potential threat to human health. Moreover, molecular sequencing and phylogenetic analyses should be carried out in future to identify the prevailing genotype (s) of E. granulosus s.s.

The global status and genetic characterization of hydatidosis in camels (Camelus dromedarius): a systematic literature review with meta-analysis based on published papers

Hydatidosis is a potential zoonotic helminthic disease affecting a broad spectrum of mammals, including humans, worldwide. The current review was conducted to investigate the genotypic status and prevalence of hydatid disease in camels across the world. For the purpose of the study, the articles addressing the worldwide prevalence of hydatidosis in camels were searched in several English language databases. The search process resulted in the inclusion of 122 papers. Based on the data presented in the reviewed articles, the pooled prevalence of hydatid disease in camels across the world was measured at 23.75% (95% CI 20.15-27.55). Moreover, the subgroup analysis demonstrated significant differences in the overall prevalence of hydatidosis among camels based on year, geographic area, climate parameters, camel population, gender, infected organ, fertility rate of the cyst and laboratory diagnostic technique. Furthermore, the Echinococcus granulosus genotypes identified in camels with hydatidosis included G1, G2, G3, G1-G3, G5, G6, G7, G6-G7 and G6-G10, with G6 being the most common genotype throughout the world. The data obtained from the current study are central to the better conceptualization of the biological and epidemiological characteristics of E. granulosus s.l. genotypes around the world, which can be helpful in the planning and adoption of more comprehensive control strategies.

Following up of Surgical Treated Human Liver Cystic Echinococcosis: A Proteomics Approach

Background:

Cystic echinococcosis (CE) is one of the most important parasitic zoonosis in the world. Post-surgery follow up in CE patients is an important non-solved problem up to now. Therefore, the investigations on this problematic issue would be very applicable in the view of CE clinical treatment.

Methods:

A total of 24 confirmed liver CE patients sera including eight sera before surgery (BS), eight sera three months post-surgery (3MPS), and eight sera six months post-surgery (6MPS) were used in the present study. Proteomics methods including 2DE and LC-MS/MS were performed on the specimens followed by bioinformatics analysis such as Gene Ontology (GO) and Protein-Protein Interaction (PPI) network analysis.

Results:

A total of 235 proteins were detected of which 12 differentially expressed proteins (DEP) were identified by LC-MS/MS in all sera. The proteins were presented in BS and suppressed after surgery as follows: HPX, SERPINA1, SERPINC1, CP, HBD, and HBA2. Comparisons of the protein expression in sera of patients BS, 3MPS, and 6MPS revealed that GC, IGJ, AHSG, CD5L, FGG, and APOC3 have been overexpressed in 3MPS and 6MPS. PPI network analysis demonstrated that SERPINC1 and AHSG with more connection in the network could be considered as hub proteins and potential prognostic biomarkers in response to surgical treatment of liver CE.

Conclusion:

Application of proteomics methods on patient’s sera could be used as a novel biomarker tool for following-up liver CE patients. In this regards, proteomics and, application of bioinformatics analysis including GO and PPI showed that SERPINC1, AHSG and HPX are of more value as a potential follow up biomarkers in response to surgical treatment.

Genotyping and phylogenetic analysis of hydatid cysts isolated from livestock in Bushehr province, Iran

Hydatid cyst is one of the parasitic zoonoses caused by infection with the larval stage of Echinococcus granulosus tapeworm. The spread of this parasite is global and is of great importance in terms of public health. To date, ten different species of this parasite have been identified that differ in characteristics such as life cycle, epidemiology and pathogenesis. The purpose of this study was to determine the genotype and phylogenetic relationship of hydatid cysts isolated from livestock of Bushehr province, Iran. About 62 samples of hepatic and pulmonary hydatid cysts were collected from slaughtered animals. DNA extracted by phenol-chloroform method was amplified by PCR using primers specific for the cox1 gene. The PCR products of 50 samples were sequenced and analyzed using BioEdit software and compared with sequences in the GenBank. The phylogenetic tree was drawn using Neighbor Joining tree-NJ method, and its reliability was evaluated. Sequencing results showed that out of 50 sequenced samples, 43 samples had the genotype of Echinococcus granulosus and 7 samples had the genotype of Taenia hydatigena. By drawing a phylogenetic tree, all 43 hydatid cyst samples belonged to G1 strain. The predominance of G1 strain of hydatid cyst in livestock of Bushehr province shows the main role of this genotype in establishing the life cycle of parasite in this region and if the genotype of the parasite in dogs and humans is determined, then these findings can be used to disrupt the life cycle of the parasite and reduce the human infections.

Comparison of various methods for DNA extraction from human isolated paraffin-embedded hydatid cyst samples

Successful molecular research with reliable results depends on achieving significant and uniform amounts of genomic DNA from the parasite as the first and most basic step. Therefore, selection of an appropriate method that minimizes damage to the DNA of the parasite, is very important. In this study, we are going to describe a method that can extract DNA from human isolated paraffin-embedded hydatid cysts with a high quality and quantity. Formalin fixed and Paraffin-embedded hydatid cyst samples isolated from human lung and archived in the pathology laboratory were used for this purpose. Several sections of the paraffin blocks were prepared with 5 micron thickness and DNA were extracted by three different methods including; modified boiling, commercial kit and the method described by Larissa A. Pikor et al. The obtained DNA were evaluated by Nanodrop in terms of the yield of DNA and possible contaminations. To compare the quality of DNA prepared, cox1 region was amplified using specific primers. It was found that the DNA extracted by modified boiling had the lowest rate of contamination and the best electrophoretic band on the gel, compared to other two performed methods. Considering the findings of this study, this simple and high throughput DNA extraction method with high yield and quality can be recommended for extraction of DNA from formalin fixed and paraffin-embedded hydatid cysts.

Molecular characterization of Echinococcus granulosus in livestock of Al-Madinah (Saudi Arabia)

Echinococcus granulosus is the causative agent of cystic echinococcosis, which has serious impacts on human and/or animal health, resulting in significant economic losses. Echinococcus granulosus comprises a number of intra-specific variants or strains at the genetic level. In Saudi Arabia, few studies were performed on genetic variations in Echinococcus species. Therefore, the present study aimed to investigate the phenotypic and genetic characterization of hydatid cysts harboured by sheep and camels in Al-Madinah Al-Munawarah. Samples of hydatid cysts were collected from local sheep (n = 25) and camels (n = 8). The morphological criteria of protoscoleces were investigated. To investigate the molecular characterization, random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR), single-stranded conformation polymorphism (SSCP) were carried out. DNA was extracted from individual fertile cysts and subjected to RAPD-PCR analysis (using five arbitrary primers) and PCR amplification of cytochrome c oxidase I (cox1) and 12S ribosomal ribonucleic acid (12S rRNA) genes. The PCR products were subjected to SSCP analysis for genetic discrimination in E. granulosus isolates. In addition, partially sequencing of the mitochondrial DNA cox1 genes was achieved for assessing the phylogenetic positions of collected isolates using some global published sequence data of cox1 genes. The rostellar hooks of camel and local sheep isolates show remarkable variability in their dimensions. Five distinct SSCP patterns were identified in the 12S rRNA gene, showing intraspecific variations in E. granulosus of camels and local sheep. Sequencing of (cox1) genes of both local sheep and camels exhibit high similarity with those of the same gene (E. granulosus sensu stricto) published in NCBI BLAST.

Comparison of molecular and morphological characterization and haplotype analysis of cattle and sheep isolates of cystic echinococcosis

Cystic echinococcosis is a zoonotic disease and the second most common foodborne parasitic infection worldwide. The aim of the present study was to investigate genetic variations in G1 and G3 genotypes of Echinococcus granulosus sensu stricto and determine the morphological differences between two genotypes. In total, 119 cystic samples were collected from 48 cattle and 71 sheep in slaughterhouses in four cities in three geographical regions of Turkey regions (Ankara, Central Anatolio region; Ordu, Black Sea region; and Adana, Mersin, Mediterranean region). For molecular characterization of the G1 and G3 genotypes, two gene regions (the complete mt-cox1 gene sequence and partial mt-nad5 gene sequence) were amplified. Haplotype analysis was conducted to determine the nucleotide differences between the complete sequences of the mt-cox1 gene for 47 samples. In addition, morphological parameters in protoscoleces of fertile cysts were measured to determine the relationship between the genotypes and morphometry. According to the obtained genotype and morphometry results, there were no statistically significant differences between the genotypes in terms of the number of hooks, total lengths of large and small hooks, blade lengths of large and small hooks, and widths of small hooks, although there was a statistically significant difference in large hook width (p > 0.05).

Genetic Diversity of Echinococcus granulosus Isolated from Humans: A Comparative Study in Two Cystic Echinococcosis Endemic Areas, Turkey and Iran

Cystic echinococcosis (CE) is one of the most important zoonotic parasitic diseases caused by the larval stage of Echinococcus granulosus. Based on molecular studies and DNA sequencing, E. granulosus has been classified into 10 different genotypes (G1 to G10). Two neighboring countries, Turkey and Iran, are considered the two main foci of CE in the Middle East. The current study is aimed at examining the genotype diversity of E. granulosus isolated from human clinical samples in Turkey and Iran. Surgically removed human hydatid cysts were collected from East Azerbaijan and Fars provinces in Iran and Van province in Turkey. After extracting DNA, performing PCR, targeting the cox1 gene, the PCR products were purified from the gel and were sequenced from both directions. The sequences were aligned and compared, using BioEdit and also the BLAST program of GenBank. The maximum likelihood tree was constructed based on the Tamura-Nei model, using the MEGAX software. Phylogenetic analysis showed that the human isolated samples were classified into two major clades: G1 (from Iran and Turkey) and G3 (5 samples from northwestern Iran and one sample from Turkey). The mean and degree of genetic divergence (K2P) between the two major clades, G1 and G3, were 0.2% and 0.7 ± 0.4%, respectively. The findings of the current study revealed that the sheep strain (G1) and the less important strain G3 have major roles in the transmission cycle of CE in two neighboring countries, Iran and Turkey. Therefore, it is necessary to interpose the life cycle of this parasite and reduce the disease burden in livestock and humans by adopting common regional preventive and control policies.

Determination of Echinococcus Granulosus Genotypes in Livestock Slaughtered in Shush County, Southwest Iran Using PCR-RFLP

Echinococosis is a zoonotic disease caused by the larval stages of Echinococcus spp. that occurs in most parts of the world. Herein, we aimed to evaluate the genotypes of isolated hydatid cysts from slaughtered animals in Shush county, southwestern Iran. Totally, 96 hydatid cysts were collected, including 11 buffaloes, 13 cattle, 12 goat and 60 sheep. The PCR was done by a primer pair (BDI and 4s) to amplify ITS1 fragment. Four restriction endonucleases including AluI, HpaII, RsaI, and TaqI were used for RFLP products and enzymatic reactions were electrophoresed. Finally, twenty PCR products were sent for sequencing and phylogenetic tree was drawn with MEGA6. Molecular identification of 96 hydatid cysts demonstrated a distinctive 1000 bp fragment in all samples from four animal hosts. RFLP analysis showed similar digestion patterns in all samples. AluI digestion yielded 800 bp and 200 bp fragments, HpaII digestion made 700 bp and 300 bp fragments and RsaI digestion entailed 655 and 345segments. Moreover, TaqI rendered no digestion pattern on rDNA-ITS1 region. Additionally, E. granulosus sensu stricto (G1-3 complex) was the prevailing genotype in all livestock samples, according to PCR-RFLP and sequencing analyses.

An analysis of common foodborne parasitic zoonoses in slaughtered sheep and cattle in Tehran, Iran, during 2015-2018

Background and Aim:

Cystic echinococcosis, Echinococcus granulosus, and liver flukes, such as Fasciola spp. and Dicrocoelium dendriticum, are important parasitic zoonoses, where they able to cause significant veterinary, medical, and economic problems. The present study was carried out to obtain the updated knowledge on the frequency of hydatidosis, fasciolosis, and dicrocoeliosis in the slaughtered sheep and cattle.

Materials and Methods:

Information were collected from meat inspection records using systematically visual inspection, palpation, and incision of the visceral organs in the industrial abattoir in Tehran, the capital of Iran, between February 1, 2015, and January 31, 2018. For an analysis of the data, SPSS version 16 was applied.

Results:

The hydatidosis infection in sheep and cattle was 2.48% and 2.25%, respectively. With respect to liver flukes, 0.62% and 0.25% sheep and cattle were infected by Fasciola spp., respectively; furthermore, 2.86% sheep and 0.79% cattle were positive for D. dendriticum.

Conclusion:

The findings will provide considerable awareness for the future monitoring and control of these potentially important infections.

Prevalence and genotypic characterization of bovine Echinococcus granulosus isolates by using cytochrome oxidase 1 (Co1) gene in Hyderabad, Pakistan

Cystic echinococcosis is an important zoonotic disease; it has serious impacts on animals as well as human health throughout the world. Genotypic characterization of Echinocossus granulosus (E. granulosus) in buffaloes has not been addressed in Pakistan. Therefore, the present study was conducted to evaluate the incidence and genotypic characterization of bovine E. granulosus. Out of 832 buffaloes examined, 112 (13.46%) were found infected. The favorable site for hydatid cyst development was liver (8.65%) followed by lungs (4.80%). The rate of cystic echinococcosis was found higher in females 14.43% than males 9.77%. The females above seven years aged were more infected as compared to the young ones. The partial sequence of mitochondrial cytochrome oxidase 1 (CO1) gene was used for identification and molecular analysis of buffalo's E. granulosus isolates. The alignment of redundant sequences were compared with already identified 10 genotypes available at National Centre for Biotechnology Information (NCBI) GenBank. The sequencing and phylogenetic analysis of all randomly selected buffalo isolates were belong to the G1- G3 complex (E. granulosus sensu stricto). All sequences were diverse from the reference sequence. No one showed complete identity to the buffalo strain (G3), representing substantial microsequence variability in G1, G2 and G3 genotypes. We evaluated the echinococcal infectivity and first time identification of genotypes in buffaloes in Sindh, Pakistan. This study will lead to determine accurate source of this zoonotic disease to humans in Pakistan.

Genetic variability of Echinococcus granulosus complex in various geographical populations of Iran inferred by mitochondrial DNA sequences

To investigate the genetic variability and population structure of Echinococcus granulosus complex, 79 isolates were sequenced from different host species covering human, dog, camel, goat, sheep and cattle as of various geographical sub-populations of Iran (Northwestern, Northern, and Southeastern). In addition, 36 sequences of other geographical populations (Western, Southeastern and Central Iran), were directly retrieved from GenBank database for the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. The confirmed isolates were grouped as G1 genotype (n=92), G6 genotype (n=14), G3 genotype (n=8) and G2 genotype (n=1). 50 unique haplotypes were identified based on the analyzed sequences of cox1. A parsimonious network of the sequence haplotypes displayed star-like features in the overall population containing IR23 (22: 19.1%) as the most common haplotype. According to the analysis of molecular variance (AMOVA) test, the high value of haplotype diversity of E. granulosus complex was shown the total genetic variability within populations while nucleotide diversity was low in all populations. Neutrality indices of the cox1 (Tajima's D and Fu's Fs tests) were shown negative values in Western-Northwestern, Northern and Southeastern populations which indicating significant divergence from neutrality and positive but not significant in Central isolates. A pairwise fixation index (Fst) as a degree of gene flow was generally low value for all populations (0.00647-0.15198). The statistically Fst values indicate that Echinococcus sensu stricto (genotype G1-G3) populations are not genetically well differentiated in various geographical regions of Iran. To appraise the hypothetical evolutionary scenario, further study is needed to analyze concatenated mitogenomes and as well a panel of single locus nuclear markers should be considered in wider areas of Iran and neighboring countries.

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.

Genotype and Phenotype of Echinococcus granulosus Derived from Wild Sheep (Ovis orientalis) in Iran

The aim of the present study is to determine the characteristics of genotype and phenotype of Echinococcus granulosus derived from wild sheep and to compare them with the strains of E. granulosus sensu stricto (sheep-dog) and E. granulosus camel strain (camel-dog) in Iran. In Khojir National Park, near Tehran, Iran, a fertile hydatid cyst was recently found in the liver of a dead wild sheep (Ovis orientalis). The number of protoscolices (n=6,000) proved enough for an experimental infection in a dog. The characteristics of large and small hooks of metacestode were statistically determined as the sensu stricto strain but not the camel strain (P=0.5). To determine E. granulosus genotype, 20 adult worms of this type were collected from the infected dog. The second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA (rDNA) and cytochrome c oxidase 1 subunit (COX1) of the mitochondrial DNA were amplified from individual adult worm by PCR. Subsequently, the PCR product was sequenced by Sanger method. The lengths of ITS2 and COX1 sequences were 378 and 857 bp, respectively, for all the sequenced samples. The amplified DNA sequences from both ribosomal and mitochondrial genes were highly similar (99% and 98%, respectively) to that of the ovine strain in the GenBank database. The results of the present study indicate that the morpho-molecular features and characteristics of E. granulosus in the Iranian wild sheep are the same as those of the sheep-dog E. granulosus sensu stricto strain.

A rare case of cerebral hydatidosis caused by a G1 genotype of Echinococcus granulosus in a cow from Iran

Hydatidosis is a medically and veterinary important parasitic disease that is endemic in many parts of the world. Unilocular hydatid cysts may develop in almost any part of the body. Up to 70% of hydatid cysts are located in the liver, followed by 25% in the lungs. Cerebral hydatidosis is an uncommon manifestation of the disease, occurring in less than 1/1000 infected hosts, yet diagnosis does pose a problem. We have reported an exceptionally rare case of cerebral hydatidosis in cattle. This is the first report to describe the characteristic pathological features of the cerebral hydatidosis in cattle caused by the G1 genotype of Echinococcus granulosus. Genotypic analysis was performed on a hydatid cyst from a cow originating from southern Iran, based on the sequence analysis of the cox1 mitochondrial gene.

The first morphometric and phylogenetic perspective on molecular epidemiology of Echinococcus granulosus sensu lato in stray dogs in a hyperendemic Middle East focus, northwestern Iran

Background

Hydatidosis is considered to be a neglected cyclo-zoonotic disease in Middle East countries particularly northwestern Iran which is caused by metacestode of tapeworm Echinococcus granulosus sensu lato. Human hydatidosis is a high public health priority in the area, however there is little known from a morphometric and phylogenetic perspective on molecular epidemiology of adult Echinococcus spp. in Iranian stray dogs.

Methods

80 dogs (38 males and 42 females) were collected during June 2013 to April 2014 in northwestern Iran. The isolated parasites from each dog were distinguished by morphometric keys including small, large hook length and blade length. Subsequently, isolates were confirmed by sequencing of mitochondrial cytochrome oxidase subunit 1 gene.

Results

16 (8 males and 8 females) (Prevalence 20 %) out of 80 dogs were infected to genus Echinococcus. With regard to demographic factors, the frequency of parasitism in both male, female adults and their age groups showed no difference (P > 0.05). The phylogenetic analyses of cox1 sequences firmly revealed the 13 sheep strains (G1), one buffalo strain (G3), one camel strain (G6) and one mixed infection. The findings of rostellar hook morphology show an intraspecies variation range among G1 isolates. However, hook measurements in Echinococcus derived from G1 (sheep strain) were not a significant difference from those G6 and G3 strains. Six unique haplotypes were identified containing a high range of diversity (Haplotype diversity 0.873 vs. Nucleotide diversity 0.02).

Conclusions

First presence of camel strain (G6) in this region seems to indicate that potential intermediate hosts play a secondary role in the maintenance of camel-dog biology. Current findings have heightened our knowledge about determination of Echinococcus prevalence, strains of taxonomy and genotypic trait of parasite in Iranian stray dogs which will also help in the development of strategies for monitoring and control of infected stray dogs in the area.

Epidemiological Investigations on Cystic Echinococcosis in North-West (Sidi Kacem Province) Morocco: Infection in Ruminants

Despite alarming statistics on cystic echinococcosis (CE) in humans and the importance of dog and ruminant populations, no epidemiological investigations have been performed on CE in Sidi Kacem Province (North-West of Morocco). A part of large research project was devoted to determine the status of CE in ruminants. This paper reports the results of the investigations carried out in the 10 abattoirs of this region, over four successive years (April 2009–March 2013). A total of 1,302 sheep, 652 head of cattle, and 136 goats were postmortem examined and hydatid cysts were collected and examined. The overall CE prevalence of infection was 42.9% in cattle, 11.0% in sheep, and 1.5% in goats. The prevalence shows significant association with age in sheep and cattle; sheep above 3 years and cattle above 5 years are highly infected (64.0% and 72.2%, resp.). Only liver and lungs are found to be infected. Molecular analyses identified G1, G2, and G3 of E. granulosus sensu stricto in liver and lung samples. Cyst fertility was significantly higher in sheep (54.9%) than in cattle (50.3%). These findings suggest that control measures should target not only sheep but also cattle.

Genetic characterization of Echinococcus granulosus from a large number of formalin-fixed, paraffin-embedded tissue samples of human isolates in Iran

Cystic echinococcosis (CE), caused by the larval stage of Echinococcus granulosus, presents an important medical and veterinary problem globally, including that in Iran. Different genotypes of E. granulosus have been reported from human isolates worldwide. This study identifies the genotype of the parasite responsible for human hydatidosis in three provinces of Iran using formalin-fixed paraffin-embedded tissue samples. In this study, 200 formalin-fixed paraffin-embedded tissue samples from human CE cases were collected from Alborz, Tehran, and Kerman provinces. Polymerase chain reaction amplification and sequencing of the partial mitochondrial cytochrome c oxidase subunit 1 gene were performed for genetic characterization of the samples. Phylogenetic analysis of the isolates from this study and reference sequences of different genotypes was done using a maximum likelihood method. In total, 54.4%, 0.8%, 1%, and 40.8% of the samples were identified as the G1, G2, G3, and G6 genotypes, respectively. The findings of the current study confirm the G1 genotype (sheep strain) to be the most prevalent genotype involved in human CE cases in Iran and indicates the high prevalence of the G6 genotype with a high infectivity for humans. Furthermore, this study illustrates the first documented human CE case in Iran infected with the G2 genotype.

Mutation scanning analysis of genetic variation within and among Echinococcus species: implications and future prospects

Adult tapeworms of the genus Echinococcus (family Taeniidae) occur in the small intestines of carnivorous definitive hosts and are transmitted to particular intermediate mammalian hosts, in which they develop as fluid-filled larvae (cysts) in internal organs (usually lung and liver), causing the disease echinococcosis. Echinococcus species are of major medical importance and also cause losses to the meat and livestock industries, mainly due to the condemnation of infected offal. Decisions regarding the treatment and control of echinococcosis rely on the accurate identification of species and population variants (strains). Conventional, phenetic methods for specific identification have some significant limitations. Despite advances in the development of molecular tools, there has been limited application of mutation scanning methods to species of Echinococcus. Here, we briefly review key genetic markers used for the identification of Echinococcus species and techniques for the analysis of genetic variation within and among populations, and the diagnosis of echinococcosis. We also discuss the benefits of utilizing mutation scanning approaches to elucidate the population genetics and epidemiology of Echinococcus species. These benefits are likely to become more evident following the complete characterization of the genomes of E. granulosus and E. multilocularis.

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

Genetic variability in the species group Echinococcus granulosus sensu lato is well recognised as affecting intermediate host susceptibility and other biological features of the parasites. Molecular methods have allowed discrimination of different genotypes (G1-10 and the 'lion strain'), some of which are now considered separate species. An accumulation of genotypic analyses undertaken on parasite isolates from human cases of cystic echinococcosis provides the basis upon which an assessment is made here of the relative contribution of the different genotypes to human disease. The allocation of samples to G-numbers becomes increasingly difficult, because much more variability than previously recognised exists in the genotypic clusters G1-3 (=E. granulosus sensu stricto) and G6-10 (Echinococcus canadensis). To accommodate the heterogeneous criteria used for genotyping in the literature, we restrict ourselves to differentiate between E. granulosus sensu stricto (G1-3), Echinococcus equinus (G4), Echinococcus ortleppi (G5) and E. canadensis (G6-7, G8, G10). The genotype G1 is responsible for the great majority of human cystic echinococcosis worldwide (88.44%), has the most cosmopolitan distribution and is often associated with transmission via sheep as intermediate hosts. The closely related genotypes G6 and G7 cause a significant number of human infections (11.07%). The genotype G6 was found to be responsible for 7.34% of infections worldwide. This strain is known from Africa and Asia, where it is transmitted mainly by camels (and goats), and South America, where it appears to be mainly transmitted by goats. The G7 genotype has been responsible for 3.73% of human cases of cystic echinococcosis in eastern European countries, where the parasite is transmitted by pigs. Some of the samples (11) could not be identified with a single specific genotype belonging to E. canadensis (G6/10). Rare cases of human cystic echinococcosis have been identified as having been caused by the G5, G8 and G10 genotypes. No cases of human infection with G4 have been described. Biological differences between the species and genotypes have potential to affect the transmission dynamics of the parasite, requiring modification of methods used in disease control initiatives. Recent investigations have revealed that the protective vaccine antigen (EG95), developed for the G1 genotype, is immunologically different in the G6 genotype. Further research will be required to determine whether the current EG95 vaccine would be effective against the G6 or G7 genotypes, or whether it will be necessary, and possible, to develop genotype-specific vaccines.

Evidence that the Echinococcus granulosus G6 genotype has an affinity for the brain in humans

The present study investigates the molecular characteristics of cerebral Echinococcus cysts. A total of 10 specimens of cerebral Echinococcus cysts, including six formalin-fixed paraffin blocks and four intact cerebral cysts, were used for this study. The target DNA was successfully amplified from eight samples and sequenced. BLAST analysis indicated that sequenced isolates belong to the Echinococcus granulosus (G6) genotype. All of the eight sampled brain cysts belonged to the G6 genotype, while all of the eight liver cysts belonged to G1. This is a strong indication that G6 has a higher affinity for the human brain than G1.

The optimum cut-off value to differentiate Echinococcus granulosus sensu stricto from other species of E. granulosus sensu lato using larval rostellar hook morphometry

Cystic echinococcosis caused by Echinococcus granulosus sensu lato is one of the most important helminth zoonoses in the world; it affects both humans and livestock. The disease is endemic in Argentina and highly endemic in the province of Neuquén. Considerable genetic and phenotypic variation has been demonstrated in E. granulosus, and ten different genotypes (G1–G10) have been identified using molecular tools. Echinococcus granulosus sensu lato may be considered a species complex, comprised of E. granulosus sensu stricto (G1–G3), E. equinus (G4), E. ortleppi (G5) and E. canadensis (G6–G10). In endemic areas, the characterization of cystic echinococcosis molecular epidemiology is important in order to apply adequate control strategies. A cut-off value for larval large hook total length to distinguish E. granulosus sensu stricto isolates from those produced by other species of the complex was defined for the first time. Overall, 1780 larval hooks of 36 isolates obtained from sheep (n= 11, G1), goats (n= 10, G6), cattle (n= 5, G6) and pigs (n= 10, G7) were analysed. Validation against molecular genotyping as gold standard was carried out using the receiver operating characteristic (ROC) curve analysis. The optimum cut-off value was defined as 26.5 μm. The proposed method showed high sensitivity (97.8%) and specificity (91.1%). Since in most endemic regions the molecular epidemiology of echinococcosis includes the coexistence of the widely distributed E. granulosus sensu stricto G1 strain and other species of the complex, this technique could be useful as a quick and economical tool for epidemiological and surveillance field studies, when fertile cysts are present.

Genotyping of Echinococcus granulosus from domestic animals and humans from Ardabil Province, northwest Iran

Cystic echinococcosis is endemic in Iran, particularly in Ardabil Province, where it causes health and economic problems. The genetic pattern of Echinococcus granulosus has been determined in most parts of Iran, except in this area. In the present investigation, 55 larval isolates were collected from humans (11), sheep (19), goats (4) and cattle (21). For analysis of the genetic characteristics of E. granulosus isolates, DNA sequencing of mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes was applied. Fifty isolates were successfully analysed, with 92% (46) and 8% (4) identified as G1 and G3 genotypes, respectively. The sequence analyses of the isolates displayed nine characteristic profiles in cox1 sequences and eight characteristic profiles in nad1 sequences. Based on these results, the sheep strain (G1 genotype) was the most prevalent in humans, sheep, goats and cattle. The buffalo strain (G3 genotype) was not only demonstrated in sheep (1 isolate) and cattle (1 isolate), but also for the first time in two human isolates. These findings will provide information for local control of echinococcosis.

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.

Molecular characterization of livestock and human isolates of Echinococcus granulosus from south-west Iran

Hydatidosis is an important public health problem in several parts of Iran. The aim of this molecular study is to investigate Echinococcus granulosus genotypes as the causative agents of hydatidosis in the south-west of Iran (Khuzestan province). In this study, isolates of 334 hydatid cysts were collected from the liver and lungs of 141 sheep, 104 cattle, 84 goats and 5 human cases. DNA was extracted and examined by nested polymerase chain reaction (PCR) of ribosomal DNA (rDNA) internal transcribed spacer 1 (ITS1) and restriction fragment length polymorphism (RFLP)-PCR. In addition, fragments of genes coding for ITS1 were sequenced. The results of RFLP-PCR analysis revealed the presence of the G1 genotype in all human, cattle, goat and sheep isolates. Furthermore, no camel strain (G6) was detected among all samples in the regions studied. The molecular findings indicate that the predominant genotype involved in E. granulosus transmission in south-west Iran is the common sheep strain (G1 genotype), which occurs in human, cattle, sheep and goat populations. In conclusion, these results may have important implications for hydatid disease control in the areas studied.

Molecular identification of animal isolates of Echinococcus granulosus from Iran using four mitochondrial genes

Mitochondrial genes have more power than nuclear genes in reconstructing phylogenetic relationships among closely related species because of their faster sequence evolution. The aim of this study was to use the complete or near-complete sequences from three mitochondrial genes (cox1, nad1 and atp6) and partial sequences of the 12S rRNA gene to infer relationships among isolates of Echinococcus granulosus from Iran. Two hundred and twenty-nine isolates of E. granulosus were collected from cattle, camels, sheep, buffalo and goats from different geographical areas. Most individuals were found to possess the G1 genotype but some of the camel samples belonged to the G6 genotype. Newly designed primers for cox1, nad1 and atp6 genes amplified bands of 1830, 708 and 1157 bp for the G1 genotype and 1856, 705, 1054 bp for the G6 genotype, respectively. The result of this survey showed that atp6 and nad1 genes are good molecular markers for identifying E. granulosus isolates from a range of hosts in Iran.

Morphological characteristics of Echinococcus granulosus derived from buffalo in Iran

Cystic echinococcosis is a significant parasitic disease in Iran, where a variety of animals act as intermediate hosts. In this study, 25 isolates of Echinococcus granulosus obtained from water buffalo from various parts of Iran were characterized on the basis of the morphology of the metacestode and the adult worm. The characteristics of protoscoleces from the different studied areas were nearly similar. They showed 2 rows of alternating large and small hooks and their shapes were smooth in outline. In contrast to the protoscoleces, the adult rostellar hooks showed a rough outline. The results showed that the total length, the blade lengths of the large and small hooks and the number of hooks are almost similar to those isolated from sheep but significantly different from those isolated from camels. The growth rates of adult E. granulosus (total worm length, segmentation and maturation) of buffalo origin, at 35 and 41 days post-infection of dogs, were nearly comparable to the common sheep strain. The form of the strobila and the morphology of the reproductive system were also similar to those of sheep origin. This suggests that the common sheep strain (G1) of E. granulosus may also use buffaloes as its intermediate host.

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.

Sequence analysis of cox1 and nad1 genes in Echinococcus granulosus G3 genotype in camels (Camelus dromedarius) from central Iran

Nineteen hydatid cyst isolates collected from camels in central Iran were subjected to sequences analysis of mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes. A consensus sequence obtained containing 366 nucleotides for cox1 and 471 nucleotides for nad1 genes. Overall, the camel isolates indicated five different sequences in cox1 and nine in nad1 genes. The sequences analysis indicated that 26.3%, 42.1%, and 31.6% of isolates belonging to G1, G3, and G6 genotypes of Echinococcus granulosus, respectively. The isolates with G3 genotype indicated one cox1 sequence having 100% homology with reference G3 sequence (AN: M84663) and two different nad1 sequences, one having 100% homology with reference G3 sequence (AN: AJ237634) and the other with a silent mutation (G to A) in position 279. The presence of G3 genotype (buffalo strain) of E. granulosus as dominant genotype in camels is emphasized. As G3 genotype has formerly been reported in human, the epidemiological role of camels is warranted in future surveys.

Rostellar hook morphology of larval Echinococcus granulosus isolates from the Indian buffalo and Iranian sheep, cattle and camel

Isolates of Echinococcus granulosus from the Indian buffalo and Iranian sheep, cattle and camels were characterized on the basis of rostellar hook morphology of the protoscolices. Results obtained indicated phenotypic polymorphism among parasites isolated from different host species. Isolates from buffalo are morphologically quite different from those of the more common sheep and cattle isolates and may represent a different strain, adapted to buffalo. In the Sari region of northern Iran, two morphologically distinct forms of E. granulosus, one in sheep and one in camels, were identified. Total length and handle length of both large and small hooks were considered the most variable characteristics which could be used not only for differentiating parasite isolates from different host species but also the origin of infection in the definitive host. We therefore suggest that larval hook morphology may be considered as a valid criterion for the identification of E. granulosus strains in Iran.