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

Cystic Echinococcosis in the Early 2020s: A Review

Cystic echinococcosis (CE) is a zoonosis caused by metacestodes, the larval stage of Echinococcus granulosus. Although the World Health Organization (WHO) has defined CE as a neglected disease, it is the second most important foodborne parasitic disease, and it remains an important public health issue, considering its zonal endemicity and potential morbidity. The control and prevention of CE is a relevant WHO target, especially from a One Health perspective, as the disease affects not only animals and humans but also the food chain. Since not all countries have a CE surveillance strategy or reporting system and specific management guidelines, recent epidemiological data are relatively scarce, and research concerning the specific geographical distribution of the disease is ongoing. To add new information to the subject, we have analyzed and collected data from national guidelines and several medical databases. Out of the 751 research articles that were originally identified, only 52 were included in the investigation after applying specific inclusion and exclusion criteria. Notable international projects that have provided significant contributions and had a positive impact are presented. The available data were correlated with WHO recommendations on the subject, thus showcasing the measures taken and those that are still needed to properly control the disease's spread.

G1 the common Echinococcus granulosus genotype infected domestic cat (Felis catus) in Iraq

BACKGROUND

Infections of cats with Echinococcus granulosus is uncommon because the cat is not part of the parasite life cycle that a carnivorous and another herbivore represent. Nevertheless, it occurs incidentally when eating food or drinking water contaminated with the worm's larva, especially with the presence of the definitive host (dogs), in this case, the infections are concentrated in stray or outside cats. For this reason, this study examined the possibility of cat infection with E. granulosus and diagnosed the common genotype of this infection.

OBJECTIVE

This study examined the possibility of cat infection with E. granulosus and diagnosed the common genotype of this infection.

METHODS

Four of the 37 cats that had died in different accidents developed cystic echinococcosis (CE). The cytochrome c oxidase subunit I (COX1) gene was initially amplified and sequenced to determine if these cysts belonged to E. granulosus, in beginning. The DNA fragments resulting from sequencing were then compared and aligned with other sequences using the Gene Bank database. Finally, a phylogenetic tree was drawn according to the sequence data obtained from cox1 genes sequencing, and the MEGA 7.0 phylogenetic analysis program was utilized.

RESULTS

Four different sequences were deposited in the Gen Bank with accession numbers (ON795961 to ON795964), all of which belong to the G1 genotype. Approximately 84% and 100% of these sequences aligned with G1 (AB622277.1) and G1 (MG722980.1), respectively.

CONCLUSIONS

G1 is the dominant genotype that causes cat infections, even though the cat's EC infection was incidental.

A novel multiplex real-time polymerase chain reaction for the molecular diagnosis of metacestode infections in human patients

OBJECTIVES

The diagnosis of larval cestodiases in humans primarily depends on using imaging techniques in combination with serological tests. However, in case of atypical imaging results, negative serology results due to immunosuppression, or infection with rare taeniid species, traditional diagnostic tools may not provide a definitive species-level diagnosis. We aimed to validate a rapid, reliable, and cost-effective single-step real-time PCR method that can identify and differentiate larval cestodiases from biopsy material.

METHODS

We validated a real-time PCR technique able to distinguish Echinococcus multilocularis, E. granulosus sensu lato (s.l.), and Taenia spp. from biopsy or cytology material in a single-step analysis. Further Sanger sequencing of E. granulosus s.l. and Taenia spp. amplicons enables differentiation of various Echinococcus and Taenia species. The assay was validated on (a) a reference sample collection of 69 clinical and veterinary cases confirmed by imaging, serology, and morphological analysis, (b) 38 routine human patient samples confirmed for aforementioned pathogens by a conventional end-point PCR, and (c) 127 samples from patients with suspected echinococcosis that were submitted to our laboratory for diagnostic analysis.

RESULTS

Compared to a conventional reference end-point PCR approach, the quadruplex real-time PCR exhibited a lower limit of detection in a serial dilution with 5-log dilutions for all three targets (2 log for E. multilocularis, 1 log for E. granulosus s.s., and 1 log for T. saginata). We were able to detect DNA from E. multilocularis, E. granulosus s.l. (E. granulosus s.s., E. canadensis, E. ortleppi, and E. felidis), a wide range of Taenia spp., as well as from non-echinococcal metacestodes such as Hydatigera taeniaformis, Hymenolepis spp., Versteria sp., and Spirometra erinaceieuropaei.

DISCUSSION

We suggest that the presented real-time PCR method is a suitable tool to be routinely used in a clinical microbiology laboratory to rapidly detect and identify larval cestodiases in human tissue.

Sensitive detection of specific cell-free DNA in serum samples from sheep with cystic echinococcosis

BACKGROUND

Developing more sensitive methods for the diagnosis of echinococcosis is essential. In this study PCR assay for sensitive detection of specific cell-free DNA (cfDNA) of Echinococcus granulosus sensu lato in the sera of the sheep naturally infected with echinococcosis was investigated.

METHODS

To extract cfDNA from 35 infected sheep, the modified phenol-chloroform method was used for two different volumes (0.5 and 2 ml) of serum samples. From each extracted sample, two DNA volumes (5 and 10 μl) were amplified using both standard PCR and semi-nested PCR targeting NADH dehydrogenase subunit I.

RESULTS

Standard and semi-nested PCR on 0.5 ml of serum samples detected Echinococcus DNA in 8 and 12 out of 35 sheep, respectively; however, using 2 ml of serum samples, they detected 24 and 27 samples. By increasing the volume of template DNA, the PCRs could detect 29 and 33 out of 35 samples. The results were confirmed by sequencing of randomly selected PCR amplicons and comparing them with GenBank databases.

CONCLUSIONS

Larger volumes of serum for DNA extraction, greater volumes of DNA template for PCR, and employing a semi-nested PCR protocol, increased the sensitivity of PCR to 95%. This approach can also be applied to the diagnosis of echinococcosis in humans.

Update on the genetic diversity and population structure of Echinococcus granulosus in Gansu Province, Tibet Autonomous Region, and Xinjiang Uygur Autonomous Region, Western China, inferred from mitochondrial cox1, nad1, and nad5 sequences

The identification of additional Echinococcus granulosus sensu lato (s.l.) complex species/genotypes in recent years raises the possibility that there might be more variation among this species in China than is currently understood. The aim of this study was to explore intra- and inter-species variation and population structure of Echinococcus species isolated from sheep in three areas of Western China. Of the isolates, 317, 322, and 326 were successfully amplified and sequenced for cox1, nad1, and nad5 genes, respectively. BLAST analysis revealed that the majority of the isolates were E. granulosus s.s., and using the cox1, nad1, and nad5 genes, respectively, 17, 14, and 11 isolates corresponded to Elodea canadensis (genotype G6/G7). In the three study areas, G1 genotypes were the most prevalent. There were 233 mutation sites along with 129 parsimony informative sites. A transition/transversion ratio of 7.5, 8, and 3.25, respectively, for cox1, nad1, and nad5 genes was obtained. Every mitochondrial gene had intraspecific variations, which were represented in a star-like network with a major haplotype with observable mutations from other distant and minor haplotypes. The Tajima's D value was significantly negative in all populations, indicating a substantial divergence from neutrality and supporting the demographic expansion of E. granulosus s.s. in the study areas. The phylogeny inferred by the maximum likelihood (ML) method using nucleotide sequences of cox1-nad1-nad5 further confirmed their identity. The nodes assigned to the G1, G3, and G6 clades as well as the reference sequences utilized had maximal posterior probability values (1.00). In conclusion, our study confirms the existence of a significant major haplotype of E. granulosus s.s. where G1 is the predominant genotype causing of CE in both livestock and humans in China.

Diagnosis of echinococcosis by detecting circulating cell-free DNA and miRNA

INTRODUCTION

Diagnosis of echinococcosis is difficult and usually performed based on clinical findings, imaging, and serological test. However, all of them have limitations, especially in follow-up approaches.

AREAS COVERED

Detection of cell-free DNA (cfDNA) and micro-RNA (miRNA) is currently a hot topic for diagnosis of echinococcosis diseases. For detecting cell-free DNA in echinococcosis patient's samples such as sera, some techniques are based on next-generation sequencing (NGS), DNA-deep sequencing, some are based on PCR-based methods, and a few works related to the detection of miRNA for the diagnosis of human echinococcosis.

EXPERT OPINION

In the detection of cell-free DNA in echinococcosis patient' samples, NGS and DNA-deep sequencing have shown high level of sensitivity, but are not suitable for routine clinical examination as they are expensive and inaccessible in the majority of endemic areas. However, PCR-based methods have shown a sensitivity of about 20-25%. To improve the sensitivity of these tests, improving the DNA extraction method, designing appropriate primers for detecting short-length fragments of circulating DNA, using a higher volume of a serum sample, and application of more sensitive PCR methods are recommended. In the field of miRNA detection, further works are recommended.

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.

A survey of intestinal helminths in domestic dogs in a human-animal-environmental interface: the Oloisukut Conservancy, Narok County, Kenya

Dogs living in a domestic-wildlife interface can serve as reservoirs and sentinels of parasites shared among humans, domestic animals and wildlife. In Kenya, the epidemiology of intestinal parasites of dogs and their role as reservoirs of zoonoses is poorly understood, especially in domestic-wildlife interfaces. This study aimed to determine the occurrence of intestinal helminths in domestic dogs in the Oloisukut Conservancy. One hundred dog faecal samples were collected per rectum and examined microscopically following zinc chloride flotation and formal-ether concentration techniques. Genotyping of helminths was achieved by nested polymerase chain reaction of NADH dehydrogenase subunit 1, cytochrome oxidase 1 and partial sequencing. Nine genera were detected by microscopy in 65 (65%) dog faecal samples from 54/76 (71.05%) households. The most frequent helminths were hookworm (39%), Spirometra spp. (17%), taeniids (13%), Toxocara spp. (10%), Trichuris spp. (10%), Spirocerca lupi (5%), Physaloptera spp. (2%), Dipylidium caninum (1%) and Strongyloides spp. (1%). Ancylostoma caninum was the only hookworm species detected in dogs, while Taenia serialis and Taenia madoquae were detected in four and one faecal samples, respectively. This study reports for the first time the molecular detection of the cestodes Spirometra theileri, D. caninum and Mesocestoides sp. in dogs in Kenya. The presence of zoonotic helminths in dogs indicates that the residents of this conservancy are exposed to public health risks. The helminths reported here confirm the interaction of domestic dogs with wildlife. An integrated control programme involving the medical, veterinary and wildlife conservation professionals is needed to avert transmission of infectious diseases to humans, domestic animals and wildlife.

LAMP Assay for the Detection of Echinococcus multilocularis Eggs Isolated from Canine Faeces by a Cost-Effective NaOH-Based DNA Extraction Method

The detection of Echinococcus multilocularis in infected canids and the environment is pivotal for a better understanding of the epidemiology of alveolar echinococcosis in endemic areas. Necropsy/sedimentation and counting technique remain the gold standard for the detection of canid infection. PCR-based detection methods have shown high sensitivity and specificity, but they have been hardly used in large scale prevalence studies. Loop-mediated isothermal amplification (LAMP) is a fast and simple method to detect DNA with a high sensitivity and specificity, having the potential for field-application. A specific LAMP assay for the detection of E. multilocularis was developed targeting the mitochondrial nad1 gene. A crucial step for amplification-based detection methods is DNA extraction, usually achieved utilising silica-gel membrane spin columns from commercial kits which are expensive. We propose two cost-effective and straightforward methods for DNA extraction, using NaOH (method 1A) and InstaGene^TM Matrix (method 1B), from isolated eggs circumventing the need for commercial kits. The sensitivity of both assays with fox samples was similar (72.7%) with multiplex-PCR using protocol 1A and LAMP using protocol 1B. Sensitivity increased up to 100% when testing faeces from 12 foxes infected with more than 100 intestinal stages of E. multilocularis. For dogs, sensitivity was similar (95.4%) for LAMP and multiplex-PCR using protocol 1B and for both methods when DNA was extracted using protocol 1A (90.9%). The DNA extraction methods used here are fast, cheap, and do not require a DNA purification step, making them suitable for field studies in low-income countries for the prevalence study of E. multilocularis.

Animal hydatid cyst genotypes as a potential substitute for human hydatid cyst as a source of antigen for diagnosis of zoonotichydatidosis

The Diagnosis of hydatidosis is still an unsolved issue due to difficulties in obtaining of patient's hydatid cyst appropriate for antigen extraction. This study evaluated the suitability of HC protoscolices somatic antigens (HCPsS-Ag) fractions from animal origin to substitute that extracted from HC of patients in diagnosis of hydatidosis using enzyme-linked immunoelectro-transfer blot and Enzyme-linked immunosorbent assay (ELISA). Eight fractions in HC-G6 from patients react specifically versus HC-G6 infected patient's sera. Five of them (28, 32, 38, 59 and 89 Kilo Dalton (KDa) and two of them (28 KDa and 45 KDa) reacted versus HC-G1 and HC-G4 infected sheep and equine sera, respectively. Six fractions in HCPsS-Ag-G1 of sheep react versus HC-G1 sheep infected sera, four (28, 32, 52 and 58 KDa) and two of them reacted versus HC-G6 and HC-G4 infected patient and equine sera, respectively. Two fractions only in HCPsS-Ag-G4 of equine reacted versus infected human and sheep sera. This fraction displayed the same degree of ELISA value versus different infected sera with a significantly perfect classification for kappa agreement and non-statistically significant difference (p ≥ 0.05) for ELISA Optical density values of the positive samples without cross-reaction versus other parasites antibodies in sera. HCPsS-Ag from HC genotypes that developed in humans and animals as HC-G6 and HC-G1 can substitute each other for diagnosis of infection than antigens extracted from non-zoonotic HC-G4. The fraction at 28 KDa is the only fraction that can be extracted from any animals HC and used in diagnosis of zoonotic hydatidosis.

A validated method to identify Echinococcus granulosus sensu lato at species level

The zoonotic tapeworm Echinococcus granulosus sensu lato (s.l.) represents a species complex encompassing multiple causative agents of cystic echinococcosis, a neglected tropical disease affecting more than one million people in the world. At least eight genotypes, grouped in five species, are currently recognized within this species complex, and they differ in terms of relative public health impact. Here we present a molecular method that first identifies the common E. granulosus sensu stricto (s.s.) (genotypes G1 and G3) based on a PCR-RFLP assay, and can further identify the remaining species based on a multiplex PCR assay. We demonstrate the applicability of the method to DNA extracted from parasitic cyst material of human and animal origin, preserved in ethanol or frozen. The method has been developed and validated at the European Union Reference Laboratory for Parasites (EURLP), according to the ISO/IE 17025.

Species Detection within the Echinococcus granulosus sensu lato Complex by Novel Probe-Based Real-Time PCRs

Infections with eggs of Echinococcus granulosus sensu lato (s.l.) can cause cystic echinococcosis in intermediate host animals and humans. Upon ingestion of viable eggs, oncospheres hatch from the eggs and subsequently develop into fluid-filled larval cysts, most frequently in the liver or the lungs. The slowly growing cysts progressively interfere with organ function. The risk of infection is determined by the host range of the parasite, its pathogenicity and other epidemiologically relevant parameters, which differ significantly among the five species within the E. granulosus s.l. complex. It is therefore essential to diagnose the correct species within E. granulosus s.l. to help understand specific disease epidemiology and to facilitate effective implementation of control measures. For this purpose, simple, fast and cost-effective typing techniques are needed. We developed quantitative real-time polymerase chain reactions (qPCRs) to target polymorphic regions in the mitochondrial genome of E. granulosus s.l. In a single-step typing approach, we distinguished E. granulosus s.l. members in four epidemiologically relevant subgroups. These were E. granulosus sensu stricto, E. equinus, E. ortleppi and the E. canadensis cluster. The technique also allowed identification and differentiation of these species from other Echinococcus or Taenia taxa for samples isolated from cysts or faeces.

Dispersal and molecular characterisation of the Echinococcus granulosus (Batsch, 1786) complex isolated from various intermediate hosts in the Calabria region, southern Italy

Cystic echinococcosis (CE) is a zoonotic disease caused by the tapeworms of the Echinococcus granulosus sensu lato complex, which have worldwide distribution. No data on the circulation of genotypes of the E. granulosus complex in intermediate hosts in endemic areas in Calabria are available. The aims of our study were to evaluate the dispersal of genotypes of the E. granulosus complex in Calabria and to characterise parasite isolates by Sanger sequencing and phylogenetic analysis. We collected 71 animal samples from pigs, wild boars, sheep, cattle and goats. The first PCR screening analysis targeted three partial genomic regions: the cytochrome c oxidase subunit 1 (cox1), calreticulin protein (cal) and NADH dehydrogenase subunit 1 (nad1); this identified 28 parasitic cysts. Bidirectional sequencing of cox1 amplicons and phylogenetic analysis allowed us to characterise all isolates. Molecular analyses of 28 newly generated cox1 sequences revealed that most wild boars (n = 16) and three pigs were parasitised by the larval stage of Taenia hydatidena Pallas, 1766, called cysticercus tenuicollis. Two isolates from wild boars were identified as Echinococcus canadensis Webster and Cameron, 1961 (G7), while five sheep and two goats were infected with E. granulosus G1 (sheep strain) and G1 microvariant (previously reported as G2 genotype or Tasmanian sheep strain), respectively. These molecular findings should prompt further and more extensive studies, to elucidate regional transmission patterns and to guide control programs.

Targeted Sequencing of Genomic Repeat Regions Detects Circulating Cell-free Echinococcus DNA

Background

Echinococcosis is a chronic zoonosis caused by tapeworms of the genus Echinococcus. Treatment of the disease is often expensive and complicated, sometimes requiring extensive surgery. Ultrasonographic imaging is currently the main technique for diagnosis, while immunological analysis provides additional information. Confirmation still needs pathological analysis. However, these diagnostic techniques generally detect infection in late stages of the disease. An accurate, early and non-invasive molecular diagnostic method is still unavailable.

Methodology/Principal findings

We sequenced the cell-free DNA (cfDNA) from plasma of echinococcosis patients and confirmed the presence of Echinococcus DNA. To improve detection sensitivity, we developed a method based on targeted next-generation sequencing of repeat regions. Simulation experiments demonstrate that the targeted sequencing is sensitive enough to detect as little as 0.1% of an Echinococcus genome in 1 mL of plasma. Results obtained using patient plasma shows that the Area Under the Curve (AUC) of the method is 0.862, with a detection sensitivity of 62.50% and specificity of 100%, corresponding to a Youden-index of 0.625.

Conclusions/Significance

This study provides evidence that hydatid cysts release cfDNA fragments into patient plasma. Using the repeat region targeted sequencing method, highly specific detection of Echinococcus infection was achieved. This study paves a new avenue for potential non-invasive screening and diagnosis of echinococcosis.

Echinococcosis is a severe chronic parasitic disease caused by tapeworms of the genus Echinococcus. According to the World Health Organization, there are more than 1 million people living with echinococcosis worldwide. For decades, little progress has been made to develop a molecular diagnosis and specific treatment for the disease. Although imaging and immunological detection are used for diagnosis, these technologies are either only effective for late stages of the disease or hardly conclusive. The detection of cell-free DNA has been a powerful tool for precise diagnosis. In this study, we showed the presence of Echinococcus-derived cell-free DNA in plasma of echinococcosis patients. We further established an assay to detect parasite DNA in blood samples based on amplification of Echinococcus specific repeat regions followed by targeted next-generation sequencing. This technique provides a new method for potential extensive screening and precision diagnosis of echinococcosis with high specificity.

A multiplex PCR for the identification of Echinococcus multilocularis, E. granulosus sensu stricto and E. canadensis that infect human

Echinococcus granulosus sensu stricto (s.s.), Echinococcus multilocularis and Echinococcus canadensis are the common causes of human echinococcosis in China. An accurate species identification tool for human echinococcosis is needed as the treatments and prognosis are different among species. The present work demonstrates a method for the simultaneous detection of these three Echinococcus species based on multiplex polymerase chain reaction (mPCR). Specific primers of this mPCR were designed based on the mitochondrial genes and determined by extensive tests. The method can successfully detect either separated or mixed target species, and generate expected amplicons of distinct size for each species. Sensitivity of the method was tested by serially diluted DNA, showing a detection threshold as less as 0.32 pg for both E. granulosus s.s. and E. canadensis, and 1.6 pg for E. multilocularis. Specificity assessed against 18 other parasites was found to be 100% except weakly cross-react with E. shiquicus. The assay was additionally applied to 69 echinococcosis patients and 38 healthy persons, confirming the high reliability of the method. Thus, the mPCR described here has high application potential for clinical identification purposes, and can further provide a useful tool for evaluation of serology and imaging method.

A multiplex PCR for differential detection of Echinococcus granulosus sensu stricto, Echinococcus multilocularis and Echinococcus canadensis in China

BACKGROUND

Echinococcosis caused by Echinococcus is one of the most major infectious diseases in north-west highland of China. E. granulosus sensu strict, E. multilocularis, and E. canadensis are known to be the only three species related to human health transmitting in the areas. To achieve targeted treatment and control of echinococcosis, the accurate identification and discrimination of the species are important. However, currently the available diagnostic approaches do not present ideal results either in accuracy or efficiency.

METHODS

In the study, a set of primers were designed to aim at the three human-pathogenic Echinococcus species in China. The one-step multiplex PCR assay was developed and evaluated for the specificity and sensitivity. A total of 73 parasitic lesions and 41 fecal materials obtained from human and various animals collected in the clinic and the field were tested to assess the applicability of this method.

RESULTS

The multiplex PCR effectively detected the individual DNA from the targeted species and their random mixtures generating with distinguishable expected size of products. The detection limit of the assay for each of the three species was 5 pg/μl when they were tested separately. When DNA mixtures of the targeted species containing the same concentration were used as templates, the lowest amount of DNA which can be detected was 50 pg/μl, 10 pg/μl and 5 pg/μl for E. granulosus s. s., E. multilocularis, and E. canadensis respectively. No cross-reactivity was observed when DNA from eight genetically close species was used as control templates. The multiplex PCR identifications of all samples were in line with the original sequencing results except for those infected with E. shiquicus, which showed negative signals in the developed assay. Of all the tested stool materials, 16 were previously found positive for Echinococcus by visual and microscopic examination. Among these 16 samples, 13 were confirmed by the multiplex PCR, and the other three tested negative. Additionally, the multiplex PCR identified another 14 positive feces from the remained 25 stool samples which absence of worms.

CONCLUSIONS

The developed multiplex PCR shows advantages in fast diagnosis and large-scale epidemiological investigation, which proven to be a promising tool utilized in clinic and surveillance system.

Genetic survey of cystic echinococcosis in farm animals in Oman

Echinococcus granulosus sensu lato (s.l.) is the causative agent of cystic echinococcosis (CE) in animals and humans with a worldwide distribution affecting pastoral and agro-pastoral communities. Little is known about the genetic diversity and public health significance of E. granulosus s.l. among animals and human in Oman. This study was undertaken to investigate the circulating genotypes of E. granulosus s.l. in farm animals (camels, cattle, goats and sheep) by using multiplex PCR (mPCR) and sequence analysis of a fragment of the NADH dehydrogenase subunit 1 (NADH-1) gene. In this study, 39 hydatid cyst isolates from dromedary camels (n = 17), cattle (n = 12), goats (n = 9) and sheep (n = 1) from five governorates in Oman were collected. These isolates were analysed genetically to classify E. granulosus s.l. using a single-tube mPCR and further subjected to sequence analysis of mitochondrial NADH-1 gene. The results of mPCR revealed that most of the cyst isolates (71.8%) belonged to E. granulosus sensu stricto G1/G2/G3 genotypes, whereas 28.2% were linked to E. canadensis G6/G7 genotypes. However, sequencing of these isolates has confirmed the existence of the two genotypes E. canadensis G6 and E. granulosus sensu stricto G1 genotype. This study provides a molecular evidence of E. granulosus s.l. genotypes in Oman and confirms the predominance of the sheep and camel strains and their role in the transmission dynamics of CE in animals. The study will serve as a foundation for future planning and implementation for CE control program in Oman.

Analysis of nad2 and nad5 enables reliable identification of genotypes G6 and G7 within the species complex Echinococcus granulosus sensu lato

The larval stages of tapeworms in the species complex Echinococcus granulosus sensu lato cause a zoonotic disease known as cystic echinococcosis (CE). Within this species complex, genotypes G6 and G7 are among the most common genotypes associated with human CE cases worldwide. However, our understanding of ecology, biology and epidemiology of G6 and G7 is still limited. An essential first step towards this goal is correct genotype identification, but distinguishing genotypes G6 and G7 has been challenging. A recent analysis based on complete mitogenome data revealed that the conventional sequencing of the cox1 (366 bp) gene fragment mistakenly classified a subset of G7 samples as G6. On the other hand, sequencing complete mitogenomes is not practical if only genotype or haplogroup identification is needed. Therefore, a simpler and less costly method is required to distinguish genotypes G6 and G7. We compared 93 complete mitogenomes of G6 and G7 from a wide geographical range and demonstrate that a combination of nad2 (714 bp) and nad5 (680 bp) gene fragments would be the best option to distinguish G6 and G7. Moreover, this method allows assignment of G7 samples into haplogroups G7a and G7b. However, due to very high genetic variability of G6 and G7, we suggest to construct a phylogenetic network based on the nad2 and nad5 sequences in order to be absolutely sure in genotype assignment. For this we provide a reference dataset of 93 concatenated nad2 and nad5 sequences (1394 bp in total) containing representatives of G6 and G7 (and haplogroups G7a and G7b), which can be used for the reconstruction of phylogenetic networks.

Genotyping of human Echinococcus granulosus cyst in Morocco

Echinococcus granulosus is the etiological agent of cystic echinococcosis (CE), also commonly called hydatidosis. This is a zoonotic infection endemic worldwide, including the Mediterranean basin and Morocco. The genetic variability of Echinococcus granulosus is known to influence development of parasitic cysts in different intermediate hosts, and therefore the epidemiology of infection. Molecular studies have identified nine genotypes of Echinococcus granulosus, eight of them affect humans, grouped today in four distinct species. In Morocco, molecular studies on CE cysts from animals showed the presence, for the large majority of cases, of the G1 genotype (« sheep strain » or Echinococcus granulosus sensu stricto), which is also the cause of the majority of human infections worldwide, and to a lesser extent of the other genotypes (G2 and G3) within Echinococcus granulosus sensu stricto complex. However, so far no genotyping of echinococcal cysts in Morocco has been carried out. We collected CE cysts material from 15 patients diagnosed with abdominal CE in the Meknès-Tafilalt region, Middle Atlas of Morocco, and an endemic area and genotyped by multiplex PCR. The only five cysts from which it was possible to successfully amplify the DNA were all belonging to the G1-G3 genotype, in line with the epidemiology of CE in animals in the same area. Our results add new information, on the human side, to the epidemiological picture of CE in the region, which are important in the context of any control plan for the infection.

Validation of a one-step PCR assay for the molecular identification of Echinococcus granulosus sensu stricto G1-G3 genotype

The Italian National Reference Center for Echinococcosis (CeNRE, Sassari, Italy) set up a diagnostic protocol of "one-step-PCR" useful for the detection of E. granulosus sensu stricto (E.g.s.s.) and the identification of its genotype (G1-G3). The purpose of this work was to perform the validation of the "PCR E.g.s.s." method. The procedures were performed employing the criteria of the World Organization for Animal Health as well as of the Italian Accreditation Body (ACCREDIA) based on the Regulation UNI CEI EN ISO/IEC 17025. Positive DNA samples belonging to E. granulosus, E. ortleppi, E. multilocularis, E. canadensis species were used for the experiments. Analytical specificity evidenced primer pairs Cal (Calreticulin l gene of 1001 bp) with an specificity higher respect to Ef1 (Elongation-Factor 1 Alpha gene of 706 bp) and NAD (Dehydrogenase-subunit 1 gene of 219 bp). The analytical sensitivity presented the capability to detect a very low amount of parasite DNA corresponding to a concentration of 12.5 pg/µl; accuracy and precision related to the operator performance, along with repeatability and reproducibility, evidenced high concordance among results and demonstrated an excellent κ values of Cohen. According to the good performance related to the evaluated parameters, the method "PCR E.g.s.s." was suitable for the validation procedure, and consequently, to be undergone to the accreditation process. In conclusion, the results demonstrated an elevated robustness and reliable features of the "PCR E.g.s.s." able to perform a rapid diagnosis of E. granulosus in only "one step", hence, it is likely to avoid the sequencing step.

Genetic Diversity of Echinococcus granulosus Genotype G1 in Xinjiang, Northwest of China

Cystic echinococcosis (CE) caused by E. granulosus is a serious helminthic zoonosis in humans, livestock and wildlife. Xinjiang is one of high endemic province for CE in China. A total of 55 sheep and cattle livers containing echinococcal cysts were collected from slaughterhouses in Changji and Yining City, northern region of Xinjiang. PCR was employed for cloning 2 gene fragments, 12S rRNA and CO1 for analysis of phylogenetic diversity of E. granulosus. The results showed that all the samples collected were identified as G1 genotype of E. granulosus. Interestingly, YL5 and CJ75 strains were the older branches compared to those strains from France, Argentina, Australia. CO1 gene fragment showed 20 new genotype haploids and 5 new genotype haplogroups (H1-H5) by the analysis of Network 5.0 software, and the YLY17 strain was identified as the most ancestral haplotype. The major haplotypes, such as CJ75 and YL5 strains, showed identical to the isolates from Middle East. The international and domestic trade of livestock might contribute to the dispersal of different haplotypes for E. granulosus evolution.

Distinguishing Echinococcus granulosus sensu stricto genotypes G1 and G3 with confidence: A practical guide

Cystic echinococcosis (CE), a zoonotic disease caused by tapeworms of the species complex Echinococcus granulosus sensu lato, represents a substantial global health and economic burden. Within this complex, E. granulosus sensu stricto (genotypes G1 and G3) is the most frequent causative agent of human CE. Currently, there is no fully reliable method for assigning samples to genotypes G1 and G3, as the commonly used mitochondrial cox1 and nad1 genes are not sufficiently consistent for the identification and differentiation of these genotypes. Thus, a new genetic assay is required for the accurate assignment of G1 and G3. Here we use a large dataset of near-complete mtDNA sequences (n = 303) to reveal the extent of genetic variation of G1 and G3 on a broad geographical scale and to identify reliable informative positions for G1 and G3. Based on extensive sampling and sequencing data, we developed a new method, that is simple and cost-effective, to designate samples to genotypes G1 and G3. We found that the nad5 is the best gene in mtDNA to differentiate between G1 and G3, and developed new primers for the analysis. Our results also highlight problems related to the commonly used cox1 and nad1. To guarantee consistent identification of G1 and G3, we suggest using the sequencing of the nad5 gene region (680 bp). This region contains six informative positions within a relatively short fragment of the mtDNA, allowing the differentiation of G1 and G3 with confidence. Our method offers clear advantages over the previous ones, providing a significantly more consistent means to distinguish G1 and G3 than the commonly used cox1 and nad1.

The benefits of analysing complete mitochondrial genomes: Deep insights into the phylogeny and population structure of Echinococcus granulosus sensu lato genotypes G6 and G7

Cystic echinococcosis (CE) is a zoonotic disease caused by the larval stage of the species complex Echinococcus granulosus sensu lato. Within this complex, genotypes G6 and G7 have been frequently associated with human CE worldwide. Previous studies exploring the genetic variability and phylogeography of genotypes G6 and G7 have been based on relatively short mtDNA sequences, and the resolution of these studies has often been low. Moreover, using short sequences, the distinction between G6 and G7 has in some cases remained challenging. The aim here was to sequence complete mitochondrial genomes (mitogenomes) to obtain deeper insight into the genetic diversity, phylogeny and population structure of genotypes G6 and G7. We sequenced complete mitogenomes of 94 samples collected from 15 different countries worldwide. The results demonstrated that (i) genotypes G6 and G7 can be clearly distinguished when mitogenome sequences are used; (ii) G7 is represented by two major haplogroups, G7a and G7b, the latter being specific to islands of Corsica and Sardinia; (iii) intensive animal trade, but also geographical isolation, have likely had the largest impact on shaping the genetic structure and distribution of genotypes G6 and G7. In addition, we found phylogenetically highly divergent haplotype from Mongolia (Gmon), which had a higher affinity to G6.

Molecular phylogeny based on six nuclear genes suggests that Echinococcus granulosus sensu lato genotypes G6/G7 and G8/G10 can be regarded as two distinct species

Tapeworms of the species complex of Echinococcus granulosus sensu lato (s. l.) are the cause of a severe zoonotic disease - cystic echinococcosis, which is listed among the most severe parasitic diseases in humans and is prioritized by the World Health Organization. A stable taxonomy of E. granulosus s. l. is essential to the medical and veterinary communities for accurate and effective communication of the role of different species in this complex on human and animal health. E. granulosus s. l. displays high genetic diversity and has been divided into different species and genotypes. Despite several decades of research, the taxonomy of E. granulosus s. l. has remained controversial, especially the species status of genotypes G6-G10. Here the Bayesian phylogeny based on six nuclear loci (7387 bp in total) demonstrated, with very high support, the clustering of G6/G7 and G8/G10 into two separate clades. According to the evolutionary species concept, G6/G7 and G8/G10 can be regarded as two distinct species. Species differentiation can be attributed to the association with distinct host species, largely separate geographical distribution and low level of cross-fertilization. These factors have limited the gene flow between genotypic groups G6/G7 and G8/G10, resulting in the formation of distinct species. We discuss ecological and epidemiological differences that support the validity of these species.

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

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

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

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

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

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

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

BACKGROUND

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

RESULTS

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

CONCLUSIONS

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

Human cystic echinococcosis in Morocco: Ultrasound screening in the Mid Atlas through an Italian-Moroccan partnership

Background

Cystic echinococcosis (CE) is a neglected parasitic zoonosis with considerable socioeconomic impact on affected pastoral communities. CE is endemic throughout the Mediterranean, including Morocco, where the Mid Atlas is the most prevalent area for both human and animal infection. The highest hospital annual incidence of human CE is recorded in the provinces of Ifrane and El Hajeb. However, hospital-based statistics likely underestimate the real prevalence of infection, as a proportion of cases never reach medical attention or official records.

Methodology/Principal findings

In 2012, a project on clinical management of CE in Morocco was launched with the aims of estimating the prevalence of human abdominal CE in selected rural communes of the above mentioned provinces using ultrasound (US) screening and training local physicians to implement US-based focused assessment and rational clinical management of CE according to the WHO-IWGE Expert Consensus. A total of 5367 people received abdominal US during four campaigns in April-May 2014. During the campaigns, 24 local general practitioners received >24 hours of hands-on training and 143 health education sessions were organized for local communities. We found an overall CE prevalence of 1.9%, with significantly higher values in the rural communes of Ifrane than El Hajeb (2.6% vs 1.3%; p<0.001). CE cysts were predominantly in inactive stage, especially in older age groups. However, active cysts were present also in adults, indicating acquisition of infection at all ages. Province of residence was the only risk factor consistently associated with CE infection.

Conclusions/Significance

Our results show a high prevalence and on-going, likely environmental transmission of CE in the investigated provinces of Morocco, supporting the implementation of control activities in the area by national health authorities and encouraging the acceptance and divulgation of diagnosis and treatment algorithms based on imaging for CE at both national and local level.

Cystic Echinococcosis (CE) is a parasitic infection whose natural domestic cycle develops between dogs and sheep (and other livestock). Human infection is endemic in pastoral communities, where close contact with the dog-sheep cycle occurs. In humans, as well as in livestock, the parasite develops as fluid-filled cyst mainly in the liver. CE is a neglected disease, as it is a disabler without high mortality, it affects mainly poor communities, and requires complex and expensive clinical management and long-term integrated public health control strategies. The prevalence of infection in an area is often unknown or largely underestimated, therefore the problem is perceived as not important. In Morocco, the Mid Atlas is the most prevalent area for human and animal infection. We performed an ultrasound survey on 5,367 people in Ifrane and El Hajeb provinces, and found an overall prevalence of 1.9%. CE cysts were predominantly inactive, however, active cysts were present also in adults. Our results show a high prevalence and on-going transmission of CE, encouraging the prompt strengthening and complete implementation of control activities envisaged by Moroccan health authorities in the area and the adoption of diagnosis and treatment algorithms based on imaging at both national and local level, to avoid a risk-associated and expensive treatment of inactive cysts.

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

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

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

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

Global Distribution of Alveolar and Cystic Echinococcosis

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

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

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

Cystic echinococcosis: Future perspectives of molecular epidemiology

Human cystic echinococcosis (CE) has been considered to be caused predominantly by Echinococcus granulosus sensu stricto (the dog-sheep strain). Molecular approaches on CE, however, have revealed that human cases are also commonly caused by another species, Echinococcus canadensis. All indices for classification and standardization of CE pathology including available images, epidemiology, diagnostics and treatment are currently based largely on a mixture of infections which include at least E. granulosus s.s. and E. canadensis. Involvement of other species of Echinococcus in CE including E. ortleppi or otherwise cryptic diversity demonstrated recently in Africa requires further elucidation. Molecular identification of the causative species in CE cases is essential for better understanding of pathogenesis and disease. This article stresses the importance of molecular species identification of human CE as a foundation for re-evaluation of evidence-based epidemiology.

Norway rat (Rattus norvegicus) as a potential reservoir for Echinococcus granulosus: A public health implication

Cystic hydatidosis is a re-emerging parasitic zoonosis with worldwide distribution. The current study was carried out to investigate the possible role of rats in the epidemiology of such disease in urban and suburban areas. For this purpose, a total of 50 feral Norway rats (Rattus norvegicus) were collected from urban and suburban settings, Cairo, Egypt. Rats were examined to be infected with cystic hydatidosis through serological examination by IHA test as well as post-mortem examination of internal organs, histopathological or molecular identification of the collected cysts. Moreover, 42 persons inhabiting suburban areas were tested for cystic hydatidosis by IHA. The overall seroprevalence rates of cystic hydatidosis in the examined rats and persons were 36% and 11.9% respectively. Cysts from 3 rats were identified as E. granulosus hydatid cysts (one via histopathological examination while the others by molecular technique and genotyped as G6 strain). The results of the current study highlight the possible role of Norway rat in the epidemiological cycle of E. granulosus especially in urban and suburban settings.

Genetic diversity and phylogeography of highly zoonotic Echinococcus granulosus genotype G1 in the Americas (Argentina, Brazil, Chile and Mexico) based on 8279bp of mtDNA

Echinococcus granulosus is a taeniid cestode and the etiological agent of an infectious zoonotic disease known as cystic echinococcosis (CE) or hydatid disease. CE is a serious public health concern in many parts of the world, including the Americas, where it is highly endemic in many regions. Echinococcus granulosus displays high intraspecific genetic variability and is divided into multiple genotypes (G1-G8, G10) with differences in their biology and etiology. Of these, genotype G1 is responsible for the majority of human and livestock infections and has the broadest host spectrum. However, despite the high significance to the public and livestock health, the data on genetic variability and regional genetic differences of genotype G1 in America are scarce. The aim of this study was to evaluate the genetic variability and phylogeography of G1 in several countries in America by sequencing a large portion of the mitochondrial genome. We analysed 8279bp of mtDNA for 52 E. granulosus G1 samples from sheep, cattle and pigs collected in Argentina, Brazil, Chile and Mexico, covering majority of countries in the Americas where G1 has been reported. The phylogenetic network revealed 29 haplotypes and a high haplotype diversity (Hd=0.903). The absence of phylogeographic segregation between different regions in America suggests the importance of animal transportation in shaping the genetic structure of E. granulosus G1. In addition, our study revealed many highly divergent haplotypes, indicating a long and complex evolutionary history of E. granulosus G1 in the Americas.

Identification of <i>Echinococcus granulosus</i> strains using polymerase chain reaction-restriction fragment length polymorphism amongst livestock in Moroto district, Uganda

A descriptive study was conducted to identify the different strains of Echinococcus granulosus occurring in livestock in Moroto district, Uganda. Echinococcus cysts from 104 domestic animals, including cattle, sheep, goats and camels, were taken and examined by microscopy, polymerase chain reaction with restriction fragment length polymorphism and Sanger DNA sequencing. Echinococcus granulosus genotypes or strains were identified through use of Bioinformatics tools: BioEdit, BLAST and MEGA6. The major finding of this study was the existence of a limited number of E. granulosus genotypes from cattle, goats, sheep and camels. The most predominant genotype was G1 (96.05%), corresponding to the common sheep strain. To a limited extent (3.95%), the study revealed the existence of Echinococcus canadensis G6/7 in three (n = 3) of the E. granulosus–positive samples. No other strains of E. granulosus were identified. It was concluded that the common sheep strain of Echinococcus sensu stricto and G6/7 of E. canadensis were responsible for echinococcal disease in Moroto district, Uganda.

A dual PCR-based sequencing approach for the identification and discrimination of Echinococcus and Taenia taxa

Reliable and rapid molecular tools for the genetic identification and differentiation of Echinococcus species and/or genotypes are crucial for studying spatial and temporal transmission dynamics. Here, we describe a novel dual PCR targeting regions in the small (rrnS) and large (rrnL) subunits of mitochondrial ribosomal RNA (rRNA) genes, which enables (i) the specific identification of species and genotypes of Echinococcus (rrnS + L-PCR) and/or (ii) the identification of a range of taeniid cestodes, including different species of Echinococcus, Taenia and some others (17 species of diphyllidean helminths). This dual PCR approach was highly sensitive, with an analytical detection limit of 1 pg for genomic DNA of Echinococcus. Using concatenated sequence data derived from the two gene markers (1225 bp), we identified five unique and geographically informative single nucleotide polymorphisms (SNPs) that allowed genotypes (G1 and G3) of Echinococcus granulosus sensu stricto to be distinguished, and 25 SNPs that allowed differentiation within Echinococcus canadensis (G6/7/8/10). In conclusion, we propose that this dual PCR-based sequencing approach can be used for molecular epidemiological studies of Echinococcus and other taeniid cestodes.

Novel PCRs for differential diagnosis of cestodes

Cestodes or tapeworms belong to a diverse group of helminths. The adult Taenia saginata and Taenia solium tapeworm can infest the human gut and the larval stage of Echinococcus spp. and T. solium can infect tissues of the human body, causing serious disease. Molecular diagnostics can be performed on proglottids, eggs and on cyst fluids taken by biopsy. Detection of cestodes when a helminthic infection is suspected is of vital importance and species determination is required for appropriate patient care. For routine diagnostics a single test that is able to detect and type a range of cestodes is preferable. We sought to improve our diagnostic procedure that used to rely on PCR and subsequent sequencing of the Cox1 and Nad1 genes. We have compared these PCRs with novel PCRs on the 12S rRNA and Nad5 gene and established the sensitivity and specificity. A single PCR on the 12S gene proved to be very suitable for detection and specification of Taenia sp. and Echinococcus sp. Both targets harbour enough polymorphic sites to determine the various Echinococcus species. The 12S PCR was most sensitive of all tested.

Discrimination between E. granulosus sensu stricto, E. multilocularis and E. shiquicus Using a Multiplex PCR Assay

BACKGROUND

Infections of Echinococcus granulosus sensu stricto (s.s), E. multilocularis and E. shiquicus are commonly found co-endemic on the Qinghai-Tibet plateau, China, and an efficient tool is needed to facilitate the detection of infected hosts and for species identification.

METHODOLOGY/PRINCIPAL FINDINGS

A single-tube multiplex PCR assay was established to differentiate the Echinococcus species responsible for infections in intermediate and definitive hosts. Primers specific for E. granulosus, E. multilocularis and E. shiquicus were designed based on sequences of the mitochondrial NADH dehydrogenase subunit 1 (nad1), NADH dehydrogenase subunit 5 (nad5) and cytochrome c oxidase subunit 1 (cox1) genes, respectively. This multiplex PCR accurately detected Echinococcus DNA without generating nonspecific reaction products. PCR products were of the expected sizes of 219 (nad1), 584 (nad5) and 471 (cox1) bp. Furthermore, the multiplex PCR enabled diagnosis of multiple infections using DNA of protoscoleces and copro-DNA extracted from fecal samples of canine hosts. Specificity of the multiplex PCR was 100% when evaluated using DNA isolated from other cestodes. Sensitivity thresholds were determined for DNA from protoscoleces and from worm eggs, and were calculated as 20 pg of DNA for E. granulosus and E. shiquicus, 10 pg of DNA for E. multilocularis, 2 eggs for E. granulosus, and 1 egg for E. multilocularis. Positive results with copro-DNA could be obtained at day 17 and day 26 after experimental infection of dogs with larval E. multilocularis and E. granulosus, respectively.

CONCLUSIONS/SIGNIFICANCE

The multiplex PCR developed in this study is an efficient tool for discriminating E. granulosus, E. multilocularis and E. shiquicus from each other and from other taeniid cestodes. It can be used for the detection of canids infected with E. granulosus s.s. and E. multilocularis using feces collected from these definitive hosts. It can also be used for the identification of the Echinococcus metacestode larva in intermediate hosts, a stage that often cannot be identified to species on visual inspection.

Echinococcus granulosus: Epidemiology and state-of-the-art of diagnostics in animals

Diagnosis and detection of Echinococcus granulosus (sensu lato) infection in animals is a prerequisite for epidemiological studies and surveillance of echinococcosis in endemic, re-emergent or emergent transmission zones. Advances in diagnostic approaches for definitive hosts and livestock, however, have not progressed equally over the last 20 years. Development of laboratory based diagnostics for canids using coproantigen ELISA and also coproPCR, have had a huge impact on epidemiological studies and more recently on surveillance during hydatid control programmes. In contrast, diagnosis of cystic echinococcosis (CE) in livestock still relies largely on conventional post-mortem inspection, despite a relatively low diagnostic sensitivity especially in early infections, as current serodiagnostics do not provide a sufficiently specific and sensitive practical pre-mortem alternative. As a result, testing of dog faecal samples by coproantigen ELISA, often combined with mass ultrasound screening programmes for human CE, has been the preferred approach for monitoring and surveillance in resource-poor endemic areas and during control schemes. In this article we review the current options and approaches for diagnosis of E. granulosus infection in definitive and animal intermediate hosts (including applications in non-domesticated species) and make conclusions and recommendations for further improvements in diagnosis for use in epidemiological studies and surveillance schemes.

First report of highly pathogenic Echinococcus granulosus genotype G1 in dogs in a European urban environment

Background

Echinococcus granulosus and E. multilocularis are tapeworm parasites of major medical and veterinary importance, causing cystic and alveolar echinococcosis, respectively. Both diseases are listed among the most severe parasitic diseases in humans, representing 2 of the 17 neglected diseases prioritised by the World Health Organisation. However, little is known about the role of urban animals in transmission of both parasite species.

Findings

A sensitive non-invasive genetic method was used to monitor E. granulosus and E. multilocularis infection among dog faecal samples collected from an urban area in Estonia in 2012–13. Out of 181 dog faecal samples analysed, 2.2% tested positive for E. granulosus, determined by sequencing as genotype G1. None of the samples tested positive for E. multilocularis.

Conclusions

We report contamination of an urban environment with highly pathogenic E. granulosus G1 disseminated by dogs, and a potential risk to human health.

Human Cystic Echinococcosis in the Nalut District of Western Libya: A Clinico-epidemiological Study

Human cystic echinococcosis (CE) is an endemic disease in the Mediterranean area that has not yet been fully documented in western Libya. The present study describes the clinico-epidemiologic profile of CE in western Libya’s Nalut district. From April 2008 to July 2011, 36 cases of CE were confirmed following surgical removal of cysts. The cysts were most frequently found in the liver (61.1%), followed by the lungs (19.4%), kidneys (11.1%), peritoneal cavity (11.1%), and spleen (5.6%). Among the 36 patients, 6 possessed plural cysts and 3 had cysts in 2 organs. Blood samples from this group were examined for the presence of serum anti-hydatid IgG antibodies, which revealed positivity in 25 patients (69.4%). An additional 300 blood samples were collected randomly from the inpatient and outpatient clinics at Nalut Hospital. Twenty-seven samples (9%) were found to be positive for the anti-hydatid IgG antibody among which the prevalence of infection tended to be higher in men (12%) than in women (6%). This study demonstrates that CE is a major parasitic infectious disease of public health significance in Libya, notably in the western part of the country, and that disease awareness needs to be raised nationwide.

Medical treatment versus "Watch and Wait" in the clinical management of CE3b echinococcal cysts of the liver

Background

Available treatments for uncomplicated hepatic cystic echinococcosis (CE) include surgery, medical therapy with albendazole (ABZ), percutaneous interventions and the watch-and-wait (WW) approach. Current guidelines indicate that patients with hepatic CE should be assigned to each option based on cyst stage and size, and patient characteristics. However, treatment indications for transitional CE3b cysts are still uncertain. These cysts are the least responsive to non-surgical treatment and often present as indolent, asymptomatic lesions that may not warrant surgery unless complicated. Evidence supporting indications for treatment of this stage is lacking. In the attempt to fill this gap before the implementation of randomized clinical trials, we compared the clinical behavior of single hepatic CE3b cysts in 60 patients followed at the WHO Collaborating Centre for Cystic Echinococcosis of the University of Pavia.

Methods

We analyzed retrospectively data of 60 patients with hepatic CE3b cysts seen at our clinic over 27 years, who either received ABZ or were monitored with WW. Univariate and multivariate analysis were performed to investigate the effect on outcome (inactivation or relapse) of variables such as age, sex, origin, treatment, cyst size and presence of other echinococcal hepatic cysts using a multiple failure Cox proportional hazard model.

Results

ABZ treatment was positively associated with inactivation (p < 0.001), but this was not permanent, and no association was found between therapeutic approach and relapse (p = 0.091). No difference was found in the rate of complications between groups.

Conclusions

In conclusion, our study shows that ABZ treatment induces temporary inactivation of CE3b cysts, while during WW cysts remain stable over time. As the rate of adverse events during periods of ABZ treatment and WW did not differ significantly in the follow-up period considered in this study (median 43 months, IQR 10.7-141.5), expectant management might represent a valuable option for asymptomatic CE3b cysts when strict indication for surgery is absent and patients comply with regular long-term follow-up.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-492) contains supplementary material, which is available to authorized users.

Genetic diversity of Echinococcus granulosus in center of Iran

Hydatid cyst caused by Echinococcus granulosus is one of the most important parasitic diseases around the world and many countries in Asia, including Iran, are involved with this infection. This disease can cause high mortality in humans as well as economic losses in livestock. To date, several molecular methods have been used to determine the genetic diversity of E. granulosus. So far, identification of E. granulosus using real-time PCR fluorescence-based quantitative assays has not been studied worldwide, also in Iran. Therefore, the aim of this study was to investigate the genetic diversity of E. granulosus from center of Iran using real-time PCR method. A total of 71 hydatid cysts were collected from infected sheep, goat, and cattle slaughtered in Isfahan, Iran during 2013. DNA was extracted from protoscolices and/or germinal layers from each individual cyst and used as template to amplify the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) (420 bp). Five cattle isolates out of 71 isolates were sterile and excluded from further investigation. Overall, of 66 isolates, partial sequences of the cox1 gene of E. granulosus indicated the presence of genotypes G1 in 49 isolates (74.2%), G3 in 15 isolates (22.7%), and G6 in 2 isolates (3.0%) in infected intermediate hosts. Sixteen sequences of G1 genotype had microgenetic variants, and they were compared to the original sequence of cox1. However, isolates identified as G3 and G6 genotypes were completely consistent with original sequences. G1 genotype in livestock was the dominant genotype in Isfahan region, Iran.