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

Establishment and application of unbiased in vitro drug screening assays for the identification of compounds against Echinococcus granulosus sensu stricto

Echinococcus multilocularis and E. granulosus s.l. are the causative agents of alveolar and cystic echinococcosis, respectively. Drug treatment options for these severe and neglected diseases are limited to benzimidazoles, which are not always efficacious, and adverse side effects are reported. Thus, novel and improved treatments are needed. In this study, the previously established platform for E. multilocularis in vitro drug assessment was adapted to E. granulosus s.s. In a first step, in vitro culture protocols for E. granulosus s.s. were established. This resulted in the generation of large amounts of E. granulosus s.s. metacestode vesicles as well as germinal layer (GL) cells. In vitro culture of these cells formed metacestode vesicles displaying structural characteristics of metacestode cysts generated in vivo. Next, drug susceptibilities of E. multilocularis and E. granulosus s.s. protoscoleces, metacestode vesicles and GL cells were comparatively assessed employing established assays including (i) metacestode vesicle damage marker release assay, (ii) metacestode vesicle viability assay, (iii) GL cell viability assay, and (iv) protoscolex motility assay. The standard drugs albendazole, buparvaquone, mefloquine, MMV665807, monepantel, niclosamide and nitazoxanide were included. MMV665807, niclosamide and nitazoxanide were active against the parasite in all four assays against both species. MMV665807 and monepantel were significantly more active against E. multilocularis metacestode vesicles, while albendazole and nitazoxanide were significantly more active against E. multilocularis GL cells. Albendazole displayed activity against E. multilocularis GL cells, but no effects were seen in albendazole-treated E. granulosus s.s. GL cells within five days. Treatment of protoscoleces with albendazole and monepantel had no impact on motility. Similar results were observed for both species with praziquantel and its enantiomers against protoscoleces. In conclusion, in vitro culture techniques and drug screening methods previously established for E. multilocularis were successfully implemented for E. granulosus s.s., allowing comparisons of drug efficacy between the two species. This study provides in vitro culture techniques for the reliable generation of E. granulosus s.s. metacestode vesicles and GL cell cultures and describes the validation of standardized in vitro drug screening methods for E. granulosus s.s.

Molecular Epidemiology of Cystic Echinococcosis in Rural Baluchistan, Pakistan: A Cross-Sectional Study

Cystic echinococcosis (CE), or hydatid cyst disease (HCD), is a zoonosis of significant importance caused by the cestode of Echinococcus granulosus sensu lato (s. l.) that affects mainly nomadic populations and has substantial economic consequences. Due to the 76% rural and nomadic population, Baluchistan is a highly endemic region in Pakistan for CE; however, it has not yet been investigated for CE. For this purpose, this study was carried out to investigate the molecular epidemiology of CE in this region. In total, 23 human hydatid cyst samples were collected from tertiary health care units in Baluchistan and processed for DNA extraction, which was then followed by sequencing of the cox1 mitochondrial gene of all 23 collected samples, genotyping, and phylogenetic and haplotype analysis. Most subjects were livestock owners (39.13%) in rural settings (73.91%). Most patients (73.19%) were pet owners (dogs) and used water from open sources for drinking. The liver was the most affected organ (52.17%), followed by the lungs (17.39%). Sequence analysis based on the cox1 gene revealed that EG genotype 1 (G1) was the most prevalent (56.52%), followed by G3 (34.78%), while some samples (8.7%) were identified as the Echinococcus canadensis (G6/7) genotype. A total of five haplotypes were detected with high haplotype diversity (0.80) and low nucleotide diversity (0.033). Phylogenetic analysis revealed two diverse sub-clades, each of G1 and G3 isolates from Baluchistan, that were evolutionarily related to previously reported G1 and G3 isolates from Pakistan and China. On the other hand, the G6/7 isolates of this study were evolutionarily identical to the already reported G6/7 isolates from Pakistan, Turkey, and Kazakhstan. This study concludes that diverse G1 and G3 EG isolates are present in this part of Pakistan, while the G6/G7 genotype was reported for the first time from Baluchistan.

Alveolar echinococcosis in nutria (Myocastor coypus), invasive species in Slovenia

The present report describes a case of Echinococcus multilocularis infection in nutria (Myocastor coypus) culled in the central area of Slovenia. Post-mortem exam showed multiple cystic lesions in the liver. Gross examination, as well as parasitological and histopathological examinations, revealed numerous cysts of various sizes, filled with yellow clear fluid and displacing most of the liver parenchyma. The cyst lumina contained numerous protoscolices approximately 100 μm in diameter and calcareous corpuscles. The protoscolices had two visible suckers and a rostellum with birefringent hooks. The lesions were consistent with an E. multilocularis cyst. Molecular analysis confirmed that the nutria was infected with E. multilocularis. To our knowledge, this is the first report of echinococcosis in nutria in Slovenia that presents gross, parasitological, and histological lesions and the result of molecular analysis. Nutrias in Slovenia are dangerous invaders but can also be a relevant bioindicator of the presence of the parasite in the environment.

Species and genotypes belonging to Echinococcus granulosus sensu lato complex causing human cystic echinococcosis in Europe (2000-2021): a systematic review

BACKGROUND

This study aimed to fill a gap of knowledge by providing a quantitative measure of molecularly identified species and genotypes belonging to Echinococcus granulosus sensu lato (s.l.) causing human cystic echinococcosis (CE) in Europe during the period 2000-2021. As these species and genotypes are characterized by genetic, animal host and geographical differences, studying the E. granulosus s.l. complex is epidemiologically relevant.

METHODS

A systematic review (SR) was conducted on the basis of both scientific and grey literature considering primary studies between 2000 and 2021 in four databases. From a total of 1643 scientific papers, 51 records were included in the SR. The main inclusion criterion for this study was the molecular confirmation of E. granulosus s.l. at the genotype/species level as a causative agent of human CE cases in selected European countries.

RESULTS

Relevant data were obtained from 29 out of 39 eligible European countries. This SR identified 599 human molecularly confirmed echinococcal cysts: 460 (76.8%) identified as E. granulosus sensu stricto (s.s.), 130 (21.7%) as E. canadensis cluster (G6/7 and G10), 7 (1.2%) as E. ortleppi (G5), and 2 as E. vogeli (0.3%). Three geographical hotspots of human CE caused by different species of the E. granulosus s.l. complex were identified: (1) E. granulosus s.s. in Southern and South-eastern Europe (European-Mediterranean and Balkan countries); (2) E. canadensis (G6/7) in Central and Eastern Europe; (3) E. ortleppi in Central and Western Europe. This SR also identified data gaps that prevented a better definition of the geographical distribution of the Echinococcus granulosus s.l. species complex in Europe: western Balkan countries, part of Central Europe, and Baltic countries.

CONCLUSIONS

These results mandate longitudinal, multi-centre, intersectoral and transdisciplinary studies which consider both molecular and clinical epidemiology in animals and humans. Such studies would be valuable for a better understanding of the transmission of the E. granulosus s.l. species complex and their potential clinical impact on humans.

Echinococcus granulosus sensu lato Genotypes in Different Hosts Worldwide: A Systematic Review

INTRODUCTION

The aim of this study was to develop a synthesis of the evidence available regarding verified E. granulosus sensu lato (s.l.) genotypes in different species worldwide.

MATERIAL AND METHODS

A systematic review was performed including studies concerning genotypes of E. granulosus s.l. without language or genotyped method restriction, published between 1990 and 2020. A systematic search was carried out in Trip Database, BIREME, SciELO, LILACS, IBECS, PAHO-WHO, EMBASE, PubMed, Scopus, and WoS. Variables of interest were year of publication, country, number of samples, and hosts; genotypes, molecular marker, haplotypes and molecular biology techniques used. Descriptive statistics were applied.

RESULTS

2411 articles were analyzed, however 135 met the selection criteria, representing 8643 liver and lung samples. Of the samples selected 24% were human, the remaining samples pertained to non-human animal hosts; cattle and sheep prevailed with 28.6% and 26.6% of the studied samples, respectively. The reported evidence is mainly from Iran, Turkey, Argentina, China and Chile; with 50, 11, 6, 6 and 5 studies, respectively, published between 1992 and 2020 [most frequently during 2015-2020 (76/135 studies; 56.3%)]. The mitochondrial gene cox1 was generally sequenced and informative (91.8%). Genotypes most frequently identified were E. granulosus sensu stricto (s.s.) (83.2%).

CONCLUSIONS

Based on this overall evidence, it can be concluded that publications related to genotypes of E. granulosus s.l. are heterogeneous. E. granulosus ss accounts for the vast majority of the global burden of E. granulosus s.l. worldwide. Further studies including larger number of cases and adequate internal validity are required to specify the distribution of genotypes in various host species.

TRIAL REGISTRATION

PROSPERO CRD42018099827.

Genetic structure and phylogeography of Echinococcus granulosus sensu stricto genotypes G1 and G3 in Pakistan and other regions of the world based on nad5 gene

Pakistan is a neglected endemic focus for Echinococcus granulosus sensu lato, a zoonotic parasite species complex with the ability to infect wide spectrum of hosts. Wide gaps exist in literature for etiological agents of cystic echinococcosis (CE) in Pakistan due to a very low number of studies on identifying the exact genotypes involved in epidemiological manifestation of this disease. Focusing on transmission patterns and epidemiological dynamics, this study aimed at investigating infective genotypes among the cattle population of south Punjab, Pakistan, employing a mitochondrial marker nad5 (680 bp). Nucleotide sequences retrieved from 28 hydatid cyst isolates displayed considerable intraspecific variation revealing the existence of G3 and G1 strains of Echinococcus granulosus sensu stricto. The G3 genotype emerged as the predominant cause (78.57%) of hydatidosis in cattle. Apart from this, to understand phylogeographical relations, homologous nucleotide sequences of the partial nad5 gene from six major regions of the world were employed in the population genetics analysis to have an insight into genetic variability and demographics of G3 genotype in particular. Diversification of G3 and its haplotypes in Pakistan (n = 11) and other regions of the world (India, Iran, Turkey, Italy and France) was demonstrated. It was further demonstrated that the South Asian population (Pakistan and India) was highly differentiated from the other regions. It could, therefore, be speculated that G3 is diverging and expanding its population with South Asia as the main focal point.

Molecular Characterization of Echinococcus granulosus sensu lato from Humans in Slovenia

The larval form of tapeworms of the Echinococcus granulosus sensu lato species cluster cause an important zoonotic infection, cystic echinococcosis (CE). Molecular characterization of the cluster’s isolates from different hosts greatly contributes to a better understanding of its transmission dynamics. To date, no genetic information is available on CE in Slovenia. In this work, we characterized isolates from human CE cases. Parasite samples from 18 patients were collected, together with the patients’ demographic and clinical data. Genomic DNA was analyzed by conventional PCR and sequencing at four mitochondrial loci (cytochrome c oxidase subunit 1, cox1; NADH dehydrogenase subunit 1, nad1; NADH dehydrogenase subunit 5, nad5; and small ribosomal RNA, rrnS). Thirteen isolates were successfully amplified and sequenced. Seven (58.8%) patients were infected with E. granulosus sensu stricto (s.s.) G1, five (38.5%) with E. canadensis G7 and one (7.7%) with E. granulosus s.s. G3. Echinococcus canadensis G7, the pig genotype, was identified exclusively in autochthonous Slovenes, while the patients originating from the Western Balkans were all infected with E. granulosus s.s. Our findings suggest that pigs are important intermediate hosts for human CE in Slovenia.

Comprehensive study based on mtDNA signature (nad1) providing insights on Echinococcus granulosus s.s. genotypes from Pakistan and potential role of buffalo-dog cycle

Pakistan has long been considered neglected endemic region for Echinococcus granulosus. Limited surveillance studies have failed to epidemiologically draw complete picture on geographical presence and etiological agents of cystic echinococcosis. Amidst such lacunae, current study explored main transmission routes of this disease through molecular characterization of hydatid cyst isolates obtained from sheep (n = 35), goats (n = 26), cattle (n = 30) and buffalo (n = 30) from the four provinces of Pakistan. Two strains of E. granulosus sensu stricto, G1/G3, and their haplotypes were observed to be cycling in sympatry in the domestic ungulate populations. G3 genotype had higher prevalence (66.94%) in the hosts compared to G1 genotype (33.06%) which was not surprising, considering the large buffalo population in Pakistan. Haplotypic analysis revealed presence of 9 different haplotypes configured in a double clustered network with two centrally positioned haplotypes referred to as G3 (PKH1) and G1 (PKH6). Population demographics and genetic variability indices suggested expanding parasitic population in multiple host spectrum. Elucidating local transmission patterns of E. granulosus sensu stricto, buffalo-dog cycle emerged as one of the dominant causes of G3 dispersal in contrary to other global studies. Adaptability of G3 to environmental conditions of Pakistan and high affinity for buffaloes emphasize on heterogeneous nature of this strain in contrast to G1. However, more studies involving larger datasets and mitochondrial sequences could confirm this hypothetically formulated inference.

Genetic characterization of Echinococcus isolates from various intermediate hosts in the Qinghai-Tibetan Plateau Area, China

This study examined Echinococcus spp. genotypes and genetic variants isolated from humans as well as domestic and wild animals from the Qinghai-Tibetan Plateau Area using the cox1 gene. All samples except the pika isolates were identified as the Echinococcus granulosus sensu stricto. Sixteen different haplotypes with considerable intraspecific variation were detected and characterized in mitochondrial cox1 sequences. The parsimonious network of cox1 haplotypes showed star-like features, and the neutrality indexes computed via Tajima's D and Fu's Fs tests showed high negative values in E. granulosus s. s., indicating deviations from neutrality; the Fst values were low among the populations, implying that the populations were not genetically differentiated. The pika isolates were identified as E. multilocularis and E. shiquicus. Only one haplotype was recognized in the pika isolates. E. granulosus s. s. was the predominant species found in animals and humans, followed by E. multilocularis and E. shiquicus, with high genetic diversity circulating among the animals and humans in this area. Further studies are needed to cover many sample collection sites and larger numbers of pathogen isolates, which may reveal abundant strains and/or other haplotypes in the hydatid cysts infecting human and animal populations of the QTPA, China.

Molecular genotyping of Echinococcus granulosus in the North of Iraq

Cystic echinococcosis/hydatidosis is an important cosmopolitan zoonotic disease that causes large economic losses and human suffering. The larval stages of Echinococcus granulosus are the etiological agents of cystic echinococcosis that showed different genotypes in different regions in the world. The present study was aimed at the detection of E. granulosus strains circulating in two cities from north of Iraq (Kirkuk and Sulaimania). A total of 47 specimens of hydatid cysts were collected from patients and from different domestic intermediate hosts including cattle, sheep, goat and buffalo from slaughterhouses. Molecular characterization was performed by direct sequencing of the mitochondrial DNA (mtDNA) genes coding for the cytochrome c oxidase I (cox1) and the small subunit ribosomal RNA (rrnS). The results showed a high prevalence for the sheep strain (G1), an isolated finding of the buffalo strain (G3) and the presence of seven and three different microvariants for cox1 and rrnS, respectively. This is the first contribution on molecular genotyping of E. granulosus in Iraq with the observation of genotypes other than G1.

Epidemiological investigation and risk factors of Echinococcus granulosus in yaks (Bos grunniens), Tibetan pigs and Tibetans on Qinghai Tibetan plateau

Echinococcus granulosus (E. granulosus) is a diverse zoonotic parasite and causes Cystic echinococcosis (CE) disease in humans and livestock. However, scare information is available about the epidemic situation of E. granulosus infection in yaks, Tibetan pigs and native Tibetans on the Qinghai Tibetan plateau. Therefore, a study was carried out to find prevalence and risk factors of E. granulosus in yaks, Tibetan pigs and Tibetans. Serum samples from yaks (1371), Tibetan pigs (454) and Tibetans (600) were collected and assessed by commercial ELISA kits. Multivariable logistic regression model was performed to find the variables possibly associated with exposure of E. granulosus infection in yaks, Tibetan pigs and Tibetan. The overall prevalence of E. granulosus in yaks was 6.49%. In different regions, the prevalence were ranged from 3.43% to 11.79%. In male and female yaks, the prevalence was 5.67% and 7.04%, respectively. In different ages, the prevalence were ranged from 2.20% to 10.9%. While, in different years, the prevalence was 3.61% in 2014, 9.66% in 2015, and 6.33% in 2016. According to the conditional stepwise logistic regression, three factors (region, age and year) were demonstrated to be risk factors influencing the prevalence of E. granulosus in yaks significantly (P<0.05). A total 33/454 of Tibetan pigs were positive for E. granulosus with the distribution of 5.47, 5.70 and 13.27% prevalence in Gongbo'gvamda, Mainling, and Nyingchi region, respectively. In male and female Tibetan pigs, the prevalence was 7.12% and 7.49% respectively, while region was considered as a significant (P<0.05) risk factor influencing the E. granulosus infection in Tibetan pigs. The total prevalence of E. granulosus infection in Tibetans was 1.83%, while in male and female Tibetans, the prevalence was 1.41% and 2.21%, respectively. In different ages, the prevalence were ranged from 0 to 3.21%. In Tibetans contacting animals or not was 2.41% and 0.54% respectively, and breeding dogs or not was 3.0% and 1.09%, respectively. Risk factors (gender age, contact animal and breed dog) were not significant (P>0.05). The present results reported the prevalence and associated risk factors of E. granulosus in yaks, Tibetan pigs and native Tibetans. These findings could have important epidemiological significance and a direct influence on the remote plateau.

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

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