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

Use of the EmsB microsatellite-based next generation sequencing for genotyping of Echinococcus granulosus sensu lato in hydatid cyst tissue samples from animals and humans

Echinococcus granulosus (Batsch, 1786), a cestode of the Teniidae family, causes human cystic echinococcosis (CE) also known as hydatid disease. Echinococcus granulosus sensu lato includes the G1, G3, G4, G5, G6/7 and G8/10 genotypes which are known to cause human CE. This study aimed to differentiate genotypes of E. granulosus s.l. complex by employing EmsB, a tandemly repeated multilocus microsatellite, using next-generation sequencing (MIC-NGS). Human and animal histopathology-confirmed hydatid cyst tissue samples and reference DNA samples of E. granulosus G1, G3, G4, G5, G6/7 and G10 underwent MIC-NGS assay with custom primers amplifying a 151 bp EmsB DNA fragment. NGS data were analysed using online Galaxy analysis pipeline, a phylogenetic tree was constructed by MEGA software, and haplotype networking was performed with PopArt 1.7. All sixty samples (49 from animals and 11 from humans) included were successfully identified and genotyped with a 100 % success rate. The study showed improved discrimination power to distinguish all study samples including closely related E. granulosus s.s. genotypes G1-G3. The maximum likelihood tree reaffirmed the monophyly of E. granulosus s.l. The median-joining haplotype networking revealed 12 distinct haplotypes. In conclusion, MIC-NGS assay was shown to be sensitive, specific and simple to apply to clinical samples offering a powerful discriminatory tool for the genotyping of E. granulosus s.l.

An innovative strategy for deworming dogs in Mediterranean areas highly endemic for cystic echinococcosis

BACKGROUND

Cystic echinococcosis (CE), caused by the larval stage of Echinococcus granulosus sensu lato, is a zoonotic parasitic disease of economic and public health importance worldwide, especially in the Mediterranean area. Canids are the main definitive hosts of the adult cestode contaminating the environment with parasite eggs released with feces. In rural and peri-urban areas, the risk of transmission to livestock as well as humans is high because of the free-roaming behavior of owned/not owned dogs. Collecting data on animal movements and behavior using GPS dataloggers could be a milestone to contain the spread of this parasitosis. Thus, this study aims to develop a comprehensive control strategy, focused on deworming a dog population in a pilot area of southern Italy (Campania region) highly endemic for CE.

METHODS

Accordingly, five sheep farms, tested to be positive for CE, were selected. In each sheep farm, all shepherd dogs present were treated every 2 months with praziquantel. Furthermore, 15 GPS dataloggers were applied to sheep and dogs, and their movements were tracked for 1 month; the distances that they traveled and their respective home ranges were determined using minimum convex polygon (MCP) analysis with a convex hull geometry as output.

RESULTS

The results showed that the mean daily walking distances traveled by sheep and dogs did not significantly differ. Over 90% of the point locations collected by GPS fell within 1500 mt of the farm, and the longest distances were traveled between 10:00 and 17:00. In all the sheep farms monitored, the area traversed by the animals during their daily activities showed an extension of < 250 hectares. Based on the home range of the animals, the area with the highest risk of access from canids (minimum safe convex polygon) was estimated around the centroid of each farm, and a potential scheme for the delivery of praziquantel-laced baits for the treatment of not owned dogs gravitating around the grazing area was designed.

CONCLUSIONS

This study documents the usefulness of geospatial technology in supporting parasite control strategies to reduce disease transmission.

Ultrasonographic verification of hepatic hydatidosis in a female dromedary camel: a case report

This report describes for the first time, the antemortem diagnosis of hydatidosis in dromedary camel based on the WHO informal working groups on echinococcosis guidelines of echinococcosis classification. The case was admitted at the University Veterinary Hospital, Qassim University, Saudi Arabia, with a history of progressive weight loss and decreased appetite for the past 4 months. Alterations in hematobiochemical parameters included leukopenia, neutropenia, decreased hematocrit percent, red blood cells count and hemoglobin concentration, hypoproteinemia, hypoalbuminemia, hyperglobulinemia, hyperglycemia and azotemia. Ultrasonographically, multiple cysts were imaged within the hepatic tissue containing anechoic fluid and fibrin tags. Ultrasound-guided aspiration of a cyst revealed a clear non-turbid fluid. Ultrasonographic diagnostic is recommended for the work-up of cystic lesions of camel liver suspected to be due to Echinococcus granulosus.

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.

High species diversity of Echinococcus spp. in wild mammals of Namibia

An opportunistic survey for Echinococcus spp. in wild mammals was conducted in seven distinct study areas throughout Namibia, representing all major ecosystems, between 2012 and 2021. In total, 184 individually attributable faeces and 40 intestines were collected from eight species of carnivores, and 300 carcasses or organs of thirteen species of ungulates were examined for Echinococcus cysts. Nested PCR and sequencing of the mitochondrial nad1 gene led to the identification of five species of the Echinococcus granulosus sensu lato complex. Echinococcus canadensis G6/7 was found throughout Namibia at low frequency in lions, cheetahs, African wild dogs, black-backed jackals and oryx antelopes. Echinococcus equinus was present only in northern Namibia, locally at high frequency in lions, black-backed jackals and plains zebras. Echinococcus felidis was found only in one small area in the north-east of Namibia, but with high frequency in lions and warthogs. Echinococcus granulosus sensu stricto was identified only in two African wild dogs in the north-east of Namibia, and Echinococcus ortleppi occurred in central and southern Namibia in black-backed jackals and oryx antelopes. The development of fertile cysts indicated active intermediate host roles of oryx antelopes for E. canadensis and E. ortleppi, of warthogs for E. felidis, and of plains zebras for E. equinus. Our data support earlier hypotheses of exclusive or predominant wildlife life-cycles for E. felidis involving lions and warthogs, and - in Namibia - for E. equinus involving lions and/or black-backed jackals and plains zebras. Our data further support an interlink of wild and domestic transmission for E. ortleppi. A possible involvement of livestock and domestic dogs in transmission of E. canadensis G6/7 and E. granulosus s.s., the two parasite species with highest zoonotic potential, is uncertain for Namibia and needs further investigation.

Wild Carnivore Survey of Echinococcus Species in Slovenia

Wild carnivores are definitive hosts and potential reservoirs for the tapeworm Echinococcus sp. which can cause cystic and alveolar echinococcosis. Both are considered neglected and important food-borne pandemics. This study is the first to molecularly test Slovenian wild carnivores for Echinococcus species that can cause disease in humans. Fecal samples from 210 red foxes (Vulpes vulpes), 42 wolves (Canis lupus), 39 golden jackals (Canis aureus), 18 martens (Marten sp.), 2 Eurasian lynx (Lynx lynx), 2 European badger (Meles meles), and 1 Eurasian otter (Lutra lutra) were examined for Echinococcus granulosus sensu lato (EGsl: E. granulosus sensu stricto, E. canadensis) and E. multilocularis (EM) using real-time PCR. Red foxes (29.1%) and golden jackals (18%) were positive for EM. All animals examined were negative for EGsl. Univariate analysis showed no significant differences in EM prevalence with respect to animal species (red fox vs., golden jackal) (p = 0.22), age (p = 0.12), and sex (p = 0.18). Prevalence of EM was associated with the region (p < 0.001), with regions in central and southern Slovenia having higher EM prevalence and risk of infection. Due to the increase in population and expansion of habitat, the golden jackal may soon become as important definitive host for EM as the red fox.

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.

Environmental Contamination by Echinococcus spp. Eggs as a Risk for Human Health in Educational Farms of Sardinia, Italy

Cystic Echinococcosis (CE) is a severe zoonosis caused by the larval stage of the tapeworm Echinococcus granulosus. These parasites are naturally transmitted between canid definitive hosts that harbour the adult stage in the intestine, and mainly ungulate intermediate hosts, with larval cysts developing in their internal organs. The close coexistence between dog and sheep with incorrect hygiene management are the most important factors for the persistence of this parasitic pathology. The Educational Farms (EF) are farms and agritourisms suitably equipped to carry out training activities for people interested in farm practices and agricultural processing, in particular student groups. Public attendance of farms represents a new potential risk factor for the zoonoses transmission. Consumption of contaminated food and water in combination with contact or playing with domestic dogs (Canis familiaris) are possible routes of zoonoses human infection. In fact, Echinococcus spp. eggs may persist in the environment up to several months at low temperatures and moist conditions, having the chance of contaminating different matrices and surfaces. The aim of this investigation was to study environmental contamination by parasitic elements as a risk for zoonoses, such as Echinococcus spp. A total of 116 samples (35 of water, 33 of soil, 23 of vegetables, 25 of dog faeces) were collected in 30 EF in Sardinia. Samples were subjected to biomolecular investigation for the research of specific gene sequences of Echinococcus granulosus, Echinococcus multilocularis and Taenia spp. The study allowed to identify eight positive EF due to the presence of Echinococcusgranulosus in eight dog faeces samples and one positive EF due to the presence of Taenia spp. in a water sample. The work has allowed to develop and harmonise the diagnostic methods and operating protocols essential for controlling the spread of the CE to create “One Health” intervention plans in high endemic areas through the implementation of SOP (standard operating procedures) for monitoring the pathology in animals, humans and environment.

DEVELOPMENT OF A TRIPLEX REAL-TIME PCR ASSAY TO DETECT ECHINOCOCCUS SPECIES IN CANID FECAL SAMPLES

Echinococcosis is a zoonotic disease with great significance to public health, and appropriate detection and control strategies should be adopted to mitigate its impact. Most cases of echinococcosis are believed to be transmitted by the consumption of food and/or water contaminated with canid stool containing Echinococcus spp. eggs. Studies assessing Echinococcus multilocularis, Echinococcus granulosus sensu stricto, and Echinococcus shiquicus coinfection from contaminated water-derived, soil-derived, and food-borne samples are scarce, which may be due to the lack of optimized laboratory detection methods. The present study aimed to develop and evaluate a novel triplex TaqMan-minor groove binder probe for real-time polymerase chain reaction (rtPCR) to simultaneously detect the 3 Echinococcus spp. mentioned above from canid fecal samples in the Qinghai-Tibetan Plateau area (QTPA). The efficiency and linearity of each signal channel in the triplex rtPCR assay were within acceptable limits for the range of concentrations tested. Furthermore, the method was shown to have good repeatability (standard deviation ≤0.32 cycle threshold), and the limit of detection was estimated to be 10 copies plasmid/μl reaction. In summary, the evaluation of the present method shows that the newly developed triplex rtPCR assay is a highly specific, precise, consistent, and stable method that could be used in epidemiological investigations of echinococcosis.

Epidemiology and spatial distribution of Echinococcus granulosus in sheep and goats slaughtered in a hyperendemic European Mediterranean area

Background

Cystic echinococcosis (CE) is a worldwide parasitic zoonosis caused by the larval stage of Echinococcus granulosus sensu lato affecting livestock, particularly sheep and goats. However, often this parasitosis is underestimated. For this reason, this study aimed to evaluate the epidemiological features and spatial distribution of CE in sheep and goats slaughtered in a hyperendemic Mediterranean area.

Methods

A survey was conducted in the Basilicata region (southern Italy) from 2014 to 2019. A total of 1454 animals (1265 sheep and 189 goats) from 824 farms were examined for hydatid cyst detection by visual inspection, palpation and incision of target organs. All the CE cysts were counted and classified into five morphostructural types (unilocular, multiseptate, calcified, caseous and hyperlaminated). Molecular analysis was performed on 353 cysts. For spatial analysis, a kriging interpolation method was used to create risk maps, while clustering was assessed by Moran’s I test.

Results

CE prevalence of 72.2% (595/824) and 58.4% (849/1454) was observed at the farm and animal levels, respectively, with higher values in sheep (62.9%) than goats (28.0%). The liver and lungs were the most frequently infected organs in both sheep and goats. Most of recovered cysts were of the calcified and multiseptate morphotypes. All the isolates were identified as E. granulosus sensu stricto (genotypes G1–G3). Spatial distribution showed a moderate clustering of positive animals.

Conclusion

The findings of this study can be used to better understand the eco-epidemiology of echinococcosis and to improve CE surveillance and prevention programs in regions highly endemic for CE.

Graphical abstract

The First Record of Echinococcus ortleppi (G5) Tapeworms in Grey Wolf (Canis lupus)

The aim of this study is to confirm the presence and molecular identification of Echinococcus tapeworms in wolves from south-eastern Poland. An investigation was carried out on the intestines of 13 wolves from south-eastern Poland. The small intestines were divided into three equal segments. Each segment was separately examined using the sedimentation and counting technique (SCT). The detected Echinococcus tapeworms were isolated and identified by PCRs and sequencing (nad1 and cox1 genes). Additionally, DNA isolated from the feces of wolves positive for Echinococcus tapeworms was examined with two diagnostic PCRs. The intestines of one wolf were positive for E. granulosus s.l. when assessed by SCT; the intestine was from a six-year-old male wolf killed in a communication accident. We detected 61 adult tapeworms: 42 in the anterior, 14 in the middle, and 5 in the posterior parts of the small intestine. The PCRs conducted for cox1 and nad1 produced specific products. A sequence comparison with the GenBank database showed similarity to the deposited E. ortleppi (G5) sequences. An analysis of the available phylogenetic sequences showed very little variation within the species of E. ortleppi (G5), and identity ranged from 99.10% to 100.00% in the case of cox1 and from 99.04% to 100.00% in the case of nad1. One of the two diagnostic PCRs used and performed on the feces of Echinococcus-positive animals showed product specific for E. granulosus. This study showed the presence of adult E. ortleppi tapeworms in wolves for the first time.

Advances in research on echinococcoses epidemiology in China

Echinococcoses are serious zoonotic diseases in China's vast, western and north-western pastoral areas that has one of the highest prevalence in the world. The two most common forms, cystic echinococcosis (CE) and alveolar echinococcosis (AE), are co-epidemic in some areas causing a grave threat to people's health and economic development. Echinococcus spp. are transmitted through domestic, sylvatic and mixed cycles involving many kinds of host. Successful transmission requires a favourable environment for the growth of the parasites and survival of their eggs, while the unique customs and religious beliefs in the endemic areas pose a challenge to the prevention and control of these parasites. Based on previous epidemiological studies, this paper reviews the particular factors affecting the transmission of Echinococcus parasites in China, with a focus on biological (parasite genotype and the species, age, sex and density of hosts), environmental (landscape and climate) and social (age, gender, ethnicity, education, occupation, life style, cultural customs, living conditions and hygiene practices of humans in the endemic areas). These three factors interact with each other and jointly determine the parasites' transmission intensity, the study of which supports the formulation of the strategies and measures that are significant for control of these infections.

An integrated approach to control Cystic Echinococcosis in southern Italy

Cystic echinococcosis (CE) is a severe zoonosis, caused by the larval stage of the tapeworm Echinococcus granulosus. This helminth infection is of increasing public health and socio-economic concern due to the considerable morbidity rates that cause economic losses both in the public health sector and in the livestock industry. Control programmes against E. granulosus are considered long-term actions which require an integrated approach and high expenditure of time and financial resources. Since 2010, an integrated approach to control CE has been implemented in a highly endemic area of continental southern Italy (Campania region). Innovative procedures and tools have been developed and exploited during the control programme based on the following strategies: i) active and passive surveillance in livestock (using geospatial tools for georeferencing), ii) diagnosis in dogs (using the FLOTAC techniques and molecular analysis), iii) targeted treatment of farm dogs (using purpose-built confinement cages), iv) early diagnosis in livestock (by ultrasonography), v) surveillance in humans (through hospital discharge records analysis), vi) monitoring the food chain (analysing raw vegetables), vii) outreach activities to the general public (through dissemination material, e.g. brochures, gadgets, videos, virtual reality). Over eight years, the integrated approach and the new strategies developed have resulted in a noteworthy reduction of the parasite infection rates in livestock (e.g. up to 30 % in sheep). The results obtained so far highlight that using a one health multidisciplinary and multi-institution effort is of pivotal importance in preparing CE control programmes at regional level and could be extended to other endemic Mediterranean areas.