Lectins are carbohydrate-binding proteins that are involved in fundamental intra- and extracellular biological processes. They occur ubiquitously in nature and are especially abundant in plants and fungi. It has been well established that certain higher fungi produce lectins in their fruiting bodies and/or sclerotia as a part of their natural resistance against free-living fungivorous nematodes and other pests. Despite relatively high diversity of the glycan structures in nature, many of the glycans targeted by fungal lectins are conserved among organisms of the same taxon and sometimes even among different taxa. Such conservation of glycans between free-living and parasitic nematodes is providing us with a useful tool for discovery of novel chemotherapeutic and vaccine targets. In our study, a subset of fungal lectins emanating from toxicity screens on Caenorhabditis elegans was tested for their potential to inhibit larval development of Haemonchus contortus.
The effect of Coprinopsis cinerea lectins - CCL2, CGL2, CGL3; Aleuria aurantia lectin – AAL; Marasmius oreades agglutinin - MOA; and Laccaria bicolor lectin – Lb-Tec2, on cultivated Haemonchus contortus larval stages was investigated using a larval development test (LDT). To validate the results of the toxicity assay and determine lectin binding capacity to the nematode digestive tract, biotinylated versions of lectins were fed to pre-infective larval stages of H. contortus and visualized by fluorescent microscopy. Lectin histochemistry on fixed adult worms was performed to investigate the presence and localisation of lectin binding sites in the disease-relevant developmental stage.
Using an improved larval development test we found that four of the six tested lectins: AAL, CCL2, MOA and CGL2, exhibited a dose-dependent toxicity in LDT, as measured by the number of larvae developing to the L3 stage. In the case of AAL, CGL2 and MOA lectin, doses as low as 5 μg/ml caused >95 % inhibition of larval development while 40 μg/ml were needed to achieve the same inhibition by CCL2 lectin. MOA was the only lectin tested that caused larval death while other toxic lectins had larvistatic effect manifesting as L1 growth arrest. Using lectin histochemistry we demonstrate that of all lectins tested, only the four toxic ones displayed binding to the larvae’s gut and likewise were found to interact with glycans localized to the gastrodermal tissue of adults.
The results of our study suggest a correlation between the presence of target glycans of lectins in the digestive tract and the lectin-mediated toxicity in Haemonchus contortus. We demonstrate that binding to the structurally conserved glycan structures found in H. contortus gastrodermal tissue by the set of fungal lectins has detrimental effect on larval development. Some of these glycan structures might represent antigens which are not exposed to the host immune system (hidden antigens) and thus have a potential for vaccine or drug development. Nematotoxic fungal lectins prove to be a useful tool to identify such targets in parasitic nematodes.
Electronic supplementary material
The online version of this article (doi:10.1186/s13071-015-1032-x) contains supplementary material, which is available to authorized users.
Haemonchus contortus; Fungal lectins; Nematotoxicity; Glycan targets; Vaccine development; Larval development test (LDT)
•Wolves are considered as definitive hosts for Echinococcus granulosus in Liguria, Italy.•Scats were examinated and taeniid eggs isolated.•Molecular species identification was performed through PCR analysis and sequencing.•Taeniid species diagnosed document domestic, semi-domestic and wildlife cycles.
Canids are definitive hosts of Taenia and Echinococcus species, which infect a variety of mammals as intermediate or accidental hosts including humans. Parasite transmission is based on domestic, semi-domestic and wildlife cycles; however, little is known of the epidemiological significance of wild large definitive hosts such as the wolf. In this study, 179 scats of wolves (Canis lupus italicus) collected throughout the Italian region of Liguria were analyzed for the detection of taeniid infection. Taeniid egg isolation was performed using a sieving/flotation technique, and the species level was identified by PCR (gene target: 12S rRNA and nad 1) followed by sequence analyses. Based on sequence homologies of ≥99%, Taenia hydatigena was identified in 19.6%, Taenia krabbei in 4.5%, Taenia ovis in 2.2%, Taenia crassiceps in 0.6%, Hydatigera taeniaeformis in 0.6% and Echinococcus granulosus in 5.6% of the samples. According to these results, Canis lupus italicus can be considered as involved in the wild (including cervids and rodents) and semi-domestic cycles (including sheep and goats) of taeniids in this area.
Liguria-Italy; Canis lupus italicus; Echinococcus granulosus; PCR; 12S; nad 1
The protozoan Eimeria tenella is a common parasite of chickens, causing avian coccidiosis, a disease of on-going concern to agricultural industries. The high prevalence of E. tenella can be attributed to the resilient oocyst stage, which is transmitted between hosts in the environment. As in related Coccidia, development of the eimerian oocyst appears to be dependent on completion of the parasite’s sexual cycle. RNA Seq transcriptome profiling offers insights into the mechanisms governing the biology of E. tenella sexual stages (gametocytes) and the potential to identify targets for blocking parasite transmission.
Comparisons between the sequenced transcriptomes of E. tenella gametocytes and two asexual developmental stages, merozoites and sporozoites, revealed upregulated gametocyte transcription of 863 genes. Many of these genes code for proteins involved in coccidian sexual biology, such as oocyst wall biosynthesis and fertilisation, and some of these were characterised in more depth. Thus, macrogametocyte-specific expression and localisation was confirmed for two proteins destined for incorporation into the oocyst wall, as well as for a subtilisin protease and an oxidoreductase. Homologues of an oocyst wall protein and oxidoreductase were found in the related coccidian, Toxoplasma gondii, and shown to be macrogametocyte-specific. In addition, a microgametocyte gamete fusion protein, EtHAP2, was discovered.
The need for novel vaccine candidates capable of controlling coccidiosis is rising and this panel of gametocyte targets represents an invaluable resource for development of future strategies to interrupt parasite transmission, not just in Eimeria but in other Coccidia, including Toxoplasma, where transmission blocking is a relatively unexplored strategy.
Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1298-6) contains supplementary material, which is available to authorized users.
Eimeria tenella; RNA Seq; Microgametocyte; Macrogametocyte; Oocyst; Fertilisation; Transmission
The apicomplexan parasite Toxoplasma gondii is cosmopolitan in nature, largely as a result of its highly flexible life cycle. Felids are its only definitive hosts and a wide range of mammals and birds serve as intermediate hosts. The latent bradyzoite stage is orally infectious in all warm-blooded vertebrates and establishes chronic, transmissible infections. When bradyzoites are ingested by felids, they transform into merozoites in enterocytes and expand asexually as part of their coccidian life cycle. In all other intermediate hosts, however, bradyzoites differentiate exclusively to tachyzoites, and disseminate extraintestinally to many cell types. Both merozoites and tachyzoites undergo rapid asexual population expansion, yet possess different effector fates with respect to the cells and tissues they develop in and the subsequent stages they differentiate into.
To determine whether merozoites utilize distinct suites of genes to attach, invade, and replicate within feline enterocytes, we performed comparative transcriptional profiling on purified tachyzoites and merozoites. We used high-throughput RNA-Seq to compare the merozoite and tachyzoite transcriptomes. 8323 genes were annotated with sequence reads across the two asexually replicating stages of the parasite life cycle. Metabolism was similar between the two replicating stages. However, significant stage-specific expression differences were measured, with 312 transcripts exclusive to merozoites versus 453 exclusive to tachyzoites. Genes coding for 177 predicted secreted proteins and 64 membrane- associated proteins were annotated as merozoite-specific. The vast majority of known dense-granule (GRA), microneme (MIC), and rhoptry (ROP) genes were not expressed in merozoites. In contrast, a large set of surface proteins (SRS) was expressed exclusively in merozoites.
The distinct expression profiles of merozoites and tachyzoites reveal significant additional complexity within the T. gondii life cycle, demonstrating that merozoites are distinct asexual dividing stages which are uniquely adapted to their niche and biological purpose.
Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1225-x) contains supplementary material, which is available to authorized users.
Toxoplasma gondii; Apicomplexa; Coccidia; Cat; Enteroepithelial development; Merozoite; Schizont; Comparative transcriptomics; Surface antigen; Stage-specific gene expression
Following the first finding of Echinococcus multilocularis in Sweden in 2011, 2985 red foxes (Vulpes vulpes) were analysed by the segmental sedimentation and counting technique. This is a labour intensive method and requires handling of the whole carcass of the fox, resulting in a costly analysis. In an effort to reduce the cost of labour and sample handling, an alternative method has been developed. The method is sensitive and partially automated for detection of E. multilocularis in faecal samples. The method has been used in the Swedish E. multilocularis monitoring program for 2012–2013 on more than 2000 faecal samples.
We describe a new semi-automated magnetic capture probe DNA extraction method and real time hydrolysis probe polymerase chain reaction assay (MC-PCR) for the detection of E. multilocularis DNA in faecal samples from red fox. The diagnostic sensitivity was determined by validating the new method against the sedimentation and counting technique in fox samples collected in Switzerland where E. multilocularis is highly endemic.
Of 177 foxes analysed by the sedimentation and counting technique, E. multilocularis was detected in 93 animals. Eighty-two (88%, 95% C.I 79.8-93.9) of these were positive in the MC-PCR. In foxes with more than 100 worms, the MC-PCR was positive in 44 out of 46 (95.7%) cases. The two MC-PCR negative samples originated from foxes with only immature E. multilocularis worms. In foxes with 100 worms or less, (n = 47), 38 (80.9%) were positive in the MC-PCR.
The diagnostic specificity of the MC-PCR was evaluated using fox scats collected within the Swedish screening. Of 2158 samples analysed, two were positive. This implies that the specificity is at least 99.9% (C.I. = 99.7 -100).
The MC-PCR proved to have a high sensitivity and a very high specificity. The test is partially automated but also possible to perform manually if desired. The test is well suited for nationwide E. multilocularis surveillance programs where sampling of fox scats is done to reduce the costs for sampling and where a test with a high sensitivity and a very high specificity is needed.
Echinococcus multilocularis; Surveillance; Red fox; Diagnostic method; Magnetic capture; Real-time PCR; Faecal samples
Infections with larval stages (metacestodes) of a variety of taeniid species have been described in primates, including humans, with partial to severe clinical consequences. Taenia martis is a tapeworm of mustelids, and martens are mainly their definitive hosts in Central Europe. In the rodent intermediate host cysticerci develop in the pleural and peritoneal cavities. The present report describes a case of T. martis peritoneal cysticercosis in a Tonkean macaque.
An abdominal mass was detected in a 3-year-old male Tonkean macaque (Macaca tonkeana) born and raised in a primate colony in France. Examination of the mass after laparotomy showed numerous vesicles identified as cysticerci of T. martis, based on the morphology of scolex and hooks, with confirmation by PCR amplification and sequence analysis of the mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes. Exeresis of the lesion was not possible and praziquantel (5.7 mg/kg) was given twice at an interval of 3 days. The abdominal mass was greatly diminished upon examination 2 months later and no signs of recurrence were noticed during the following 4 years.
This is the first report of T. martis cysticercosis in a monkey. This record and the recent first description of an ocular T. martis cysticercosis in a human show the susceptibility of primates to T. martis and its zoonotic potential. This taeniid species must be considered in the differential diagnosis of cysticercosis in primates.
Taenia martis; Cysticercosis; Zoonosis; Macaca tonkeana; France
Tapeworms cause debilitating neglected diseases that can be deadly and often require surgery due to ineffective drugs. Here we present the first analysis of tapeworm genome sequences using the human-infective species Echinococcus multilocularis, E. granulosus, Taenia solium and the laboratory model Hymenolepis microstoma as examples. The 115-141 megabase genomes offer insights into the evolution of parasitism. Synteny is maintained with distantly related blood flukes but we find extreme losses of genes and pathways ubiquitous in other animals, including 34 homeobox families and several determinants of stem cell fate. Tapeworms have species-specific expansions of non-canonical heat shock proteins and families of known antigens; specialised detoxification pathways, and metabolism finely tuned to rely on nutrients scavenged from their hosts. We identify new potential drug targets, including those on which existing pharmaceuticals may act. The genomes provide a rich resource to underpin the development of urgently needed treatments and control.
HSP70; parasitism; Cestoda; cysticercosis; echinococcosis; Platyhelminthes
Characterizing the force of infection (FOI) is an essential part of planning cost effective control strategies for zoonotic diseases. Echinococcus multilocularis is the causative agent of alveolar echinococcosis in humans, a serious disease with a high fatality rate and an increasing global spread. Red foxes are high prevalence hosts of E. multilocularis. Through a mathematical modelling approach, using field data collected from in and around the city of Zurich, Switzerland, we find compelling evidence that the FOI is periodic with highly variable amplitude, and, while this amplitude is similar across habitat types, the mean FOI differs markedly between urban and periurban habitats suggesting a considerable risk differential. The FOI, during an annual cycle, ranges from (0.1,0.8) insults (95% CI) in urban habitat in the summer to (9.4, 9.7) (95% CI) in periurban (rural) habitat in winter. Such large temporal and spatial variations in FOI suggest that control strategies are optimal when tailored to local FOI dynamics.
Human alveolar echinococcosis (AE) is caused by the fox tapeworm E. multilocularis and has a high fatality rate if untreated. The frequency of the tapeworm in foxes can be reduced through the regular distribution of anthelmintic baits and thus decrease the risk of zoonotic transmission. Here, we estimate the force of infection to foxes using a mathematical model and data from necropsied foxes. The results suggest that the frequency of anthelmintic baiting of foxes can be optimised to local variations in transmission that depend upon season and type of fox habitat.
Angiostrongylus vasorum is a potentially fatal canine nematode. Due to the high variability of clinical signs and the often chronic and subtle course of the infections, the diagnosis is particularly challenging. A rapid in-clinic assay (Angio Detect™ Test, IDEXX Laboratories, Westbrook, Maine, USA) for the serological detection of circulating antigen and intended for routine in-clinic diagnosis has been evaluated.
Sensitivity was calculated with sera from 39 naturally infected dogs confirmed by Baermann-Wetzel analysis, while sera of 38 experimentally infected dogs were used for follow-up analyses, of which 10 were treated with imidacloprid/moxidectin. Cross-reactivity was tested with a total of 123 samples from dogs with proven parasitic infections with Toxocara canis (n = 21), Ancylostoma caninum (n = 4), Crenosoma vulpis (n = 18), Oslerus osleri (n = 3), Eucoleus aerophilus, (n = 6), Dirofilaria immitis (n = 28), Dirofilaria repens (n = 20), Acantocheilonema reconditum (n = 10) or Dipetalonema dracunculoides (n = 10) or multiple infections (n = 3). All sera were tested with the Angio Detect™ Test and with an ELISA for detection of circulating antigen of A. vasorum.
The sensitivity of the Angio Detect™ Test was 84.6% (95% C.I. 69.5 - 94.1%), while specificity was 100% (95% C.I. 97.6 - 100%). The sensitivity of the ELISA (94.9%, 95% C.I. 82.7 – 99.3%) was comparable with previous evaluations. In experimentally infected dogs, earliest positive results with the Angio Detect™ Test were observed 9 weeks post inoculation and 5 weeks later all sera were Angio Detect™ Test positive. After anthelmintic treatment, seropositive dogs turned negative again within 3 to 7 weeks after treatment. The evaluation of the colour intensity of the test strips confirmed the delay of approximately 3-4 weeks for antigen detection by the Angio Detect™ Test compared to the ELISA and its correlation with the time after infection.
This study provided evidence of a good sensitivity and a very high specificity of the rapid device Angio Detect™ Test for detection of circulating A. vasorum antigen in dogs with suspected canine angiostrongylosis, representing a very simple and useful tool to be broadly applied in veterinary practices. The rapid detection of infected dogs is a key point for initiating an indispensable and urgent therapy.
Angiostrongylus vasorum; Dogs; Serological diagnosis; Rapid device test; Antigen detection; Specificity; Sensitivity
Human echinococcosis is a reportable disease in Kyrgyzstan. Between 1995 and 2011, human alveolar echinococcosis increased from <3 cases per year to >60 cases per year. The origins of this epidemic, which started in 2004, may be linked to the socioeconomic changes that followed the dissolution of the former Soviet Union.
Echinococcus multilocularis; emergence; Alveolar echinococcosis; Kyrgyzstan; Central Asia; tapeworms; parasites; zoonoses
Toxoplasmosis is one of the most common food borne zoonoses worldwide, and can be a serious life-threatening disease in the congenitally infected fetus and in immunosupressed patients. Among food animals, sheep along with goats and pigs possess the highest incidence of T. gondii cysts in meat, and play a major role as a source of human infection.
In this study, a new commercial ELISA kit (PrioCHECK® Toxoplasma Ab SR, Prionics Schlieren-Zurich, Switzerland) for the detection of anti-T. gondii antibodies in serum, plasma and meat juice of sheep, was evaluated by comparing it with the indirect fluorescent antibody test (IFAT), indirect haemagglutination test (IHA) and real-time PCR, on samples from experimentally inoculated and naturally exposed sheep.
The commercial ELISA detected the infection status in 50% and 100% of sheep orally inoculated with 10,000 T. gondii oocysts (n = 6), from two or three weeks post infection (wpi), respectively, both on serum and plasma samples. Meat juice from all experimentally inoculated sheep collected at slaughter (12 wpi) showed positive ELISA values. In naturally exposed sheep (n = 396), the ELISA showed a very good agreement with IFAT (kappa = 0.91-1.0) and IHA (kappa = 0.96-1.0) performed on serum; and a positive correlation was observed between ELISA values and IFAT titers. By a Receiver Operating Characteristics (ROC) curve analysis, the commercial ELISA had relative sensitivities between 93.33% and 100%, and relative specificities between 96.87% and 100% respect to IFAT and IHA, depending on the considered cut-off value and animal groups tested. Furthermore, the ELISA correctly recognized all animals reacting positive in real-time PCR. The ELISA results on meat juice agreed with those on serum samples in all experimentally inoculated animals, and in 94 out of 96 (97.9%) naturally exposed sheep, when meat juice was tested at a 1:10 dilution.
The commercial ELISA kit evaluated in this study could represent a valuable tool to improve the surveillance and reporting system for T. gondii in sheep populations at the farm level or for diagnosis at the slaughterhouse, contributing to the control of this widespread zoonosis.
Toxoplasma gondii; Sheep; Diagnosis; ELISA; IFAT; Indirect haemagglutination; Antibodies; Meat juice
Considering the increasing importance of small animals travel medicine and the spread of filariae with zoonotic potential to non-endemic European areas, routine filarial diagnosis in dogs is becoming important. Dirofilaria immitis, D. repens, Acanthocheilonema dracunculoides and A. reconditum are the most common canine filarial nematodes presenting blood circulating microfilariae (mf) which can be differentiated to species level by the acid phosphatase activity patterns or by PCR. Available data on the size of the mf vary considerably in the literature. The aim of this study was to validate morphometric criteria for filarial identification in blood samples of dogs after concentration of mf with the modified Knott’s technique.
Morphometric analysis of 10 mf from samples identified to species level by acid phosphatase activity and partially confirmed by PCR were performed with specimens from 377 dogs.
The mean length and width of D. immitis mf from 60 dogs were 301.77±6.29 μm and 6.30±0.26 μm, of D. repens mf from 171 dogs 369.44±10.76 μm 8.87±0.58 μm, of A. dracunculoides mf from 133 dogs 259.43±6.69 μm and 5.09±0.47 μm and of A. reconditum mf from 13 dogs 264.83±5.47 μm and 4.63±0.52 μm.
For a subset of 30 samples, morphometric analysis was repeated with identical results in two laboratories. Furthermore, the size of mf concentrated and fixed by the Knott’s technique was shown to be stable over 105 days.
The Knott’s test enables to clearly distinguish between D. immitis, D. repens and Acanthocheilonema spp. However, due to the overlapping size ranges of A. dracunculoides and A. reconditum, biochemical or molecular methods are required to distinguish these two species.
Canine blood microfilariae; Laboratory diagnosis; Size of microfilariae
HIV-prevalence, as well as incidence of zoonotic parasitic diseases like cystic echinococcosis, has increased in the Kyrgyz Republic due to fundamental socio-economic changes after the breakdown of the Soviet Union. The possible impact on morbidity and mortality caused by Toxoplasma gondii infection in congenital toxoplasmosis or as an opportunistic infection in the emerging AIDS pandemic has not been reported from Kyrgyzstan.
We screened 1,061 rural and 899 urban people to determine the seroprevalence of T. gondii infection in 2 representative but epidemiologically distinct populations in Kyrgyzstan. The rural population was from a typical agricultural district where sheep husbandry is a major occupation. The urban population was selected in collaboration with several diagnostic laboratories in Bishkek, the largest city in Kyrgyzstan. We designed a questionnaire that was used on all rural subjects so a risk-factor analysis could be undertaken. The samples from the urban population were anonymous and only data with regard to age and gender was available. Estimates of putative cases of congenital and AIDS-related toxoplasmosis in the whole country were made from the results of the serology. Specific antibodies (IgG) against Triton X-100 extracted antigens of T. gondii tachyzoites from in vitro cultures were determined by ELISA. Overall seroprevalence of infection with T. gondii in people living in rural vs. urban areas was 6.2% (95%CI: 4.8–7.8) (adjusted seroprevalence based on census figures 5.1%, 95% CI 3.9–6.5), and 19.0% (95%CI: 16.5–21.7) (adjusted 16.4%, 95% CI 14.1–19.3), respectively, without significant gender-specific differences. The seroprevalence increased with age. Independently low social status increased the risk of Toxoplasma seropositivity while increasing numbers of sheep owned decreased the risk of seropositivity. Water supply, consumption of unpasteurized milk products or undercooked meat, as well as cat ownership, had no significant influence on the risk for seropositivity.
We present a first seroprevalence analysis for human T. gondii infection in the Kyrgyz Republic. Based on these data we estimate that 173 (95% CI 136–216) Kyrgyz children will be born annually to mothers who seroconverted to toxoplasmosis during pregnancy. In addition, between 350 and 1,000 HIV-infected persons are currently estimated to be seropositive for toxoplasmosis. Taken together, this suggests a substantial impact of congenital and AIDS-related symptomatic toxoplasmosis on morbidity and mortality in Kyrgyzstan.
A serological study on toxoplasmosis was undertaken in a rural and urban population in Kyrgyzstan. The observed seroprevalence was adjusted because of differences between age and gender stratifications in the study group compared to population census figures. This gave an estimated seroprevalence in rural and urban populations of 5.1% and 16.4% respectively. In our analysis we determined the risk-factors for infection in the rural population to be age, low social-status and low number of sheep owned. While the seroprevalence in this rural population was relatively low, the seroprevalence found in the urban population of Bishkek correlated better with international data. Extrapolating from our data, about 173 seroconversions during pregnancy may be expected annually in Kyrgyzstan. In addition, considering a prevalence of HIV-Toxoplasma-co-infection between 7/100,000 (official HIV-prevalence data) and 19.4/100,000 (UNAIDS-estimates), 350–1,000 people are at risk for AIDS-related toxoplasmosis. Therefore, in the face of the rising prevalence of HIV infection education of medical personnel on treatment and prevention of toxoplasmosis is recommended.
Echinococcus granulosus is characterized by high intra-specific variability (genotypes G1–G10) and according to the new molecular phylogeny of the genus Echinococcus, the E. granulosus complex has been divided into E. granulosus sensu stricto (G1–G3), E. equinus (G4), E. ortleppi (G5), and E. canadensis (G6–G10). The molecular characterization of E. granulosus isolates is fundamental to understand the spatio-temporal epidemiology of this complex in many endemic areas with the simultaneous occurrence of different Echinococcus species and genotypes. To simplify the genotyping of the E. granulosus complex we developed a single-tube multiplex PCR (mPCR) allowing three levels of discrimination: (i) Echinococcus genus, (ii) E. granulosus complex in common, and (iii) the specific genotype within the E. granulosus complex. The methodology was established with known DNA samples of the different strains/genotypes, confirmed on 42 already genotyped samples (Spain: 22 and Bulgaria: 20) and then successfully applied on 153 unknown samples (Tunisia: 114, Algeria: 26 and Argentina: 13). The sensitivity threshold of the mPCR was found to be 5 ng Echinoccoccus DNA in a mixture of up to 1 µg of foreign DNA and the specificity was 100% when template DNA from closely related members of the genus Taenia was used. Additionally to DNA samples, the mPCR can be carried out directly on boiled hydatid fluid or on alkaline-lysed frozen or fixed protoscoleces, thus avoiding classical DNA extractions. However, when using Echinococcus eggs obtained from fecal samples of infected dogs, the sensitivity of the mPCR was low (<40%). Thus, except for copro analysis, the mPCR described here has a high potential for a worldwide application in large-scale molecular epidemiological studies on the Echinococcus genus.
The dog tapeworm Echinococcus granulosus (E. granulosus) is a cosmopolitan parasite. The adult worms reside in the small intestine of their definitive hosts (dogs). Infective eggs are shed with the feces into the environment and are orally ingested by intermediate hosts where they develop into the metacestode (larval) stage, causing cystic echinococcosis (CE) in humans and livestock. Ten intraspecific genotypes of E. granulosus (G1 to G10) have been reported from different intermediate host species. Based on the recently established molecular phylogeny, E. granulosus is now considered a complex consisting of four species: E. granulosus sensu stricto (G1/G2/G3), E. equinus (G4), E. ortleppi (G5) and E. canadensis (G6–G10). Simple and highly discriminative molecular epidemiological approaches are needed to explore dynamics, life cycle patterns, and the pathogenicity of the members of this complex. We here introduce a one-step multiplex PCR (mPCR) protocol for the genotyping and discrimination of the different members of the E. granulosus complex, allowing three levels of discrimination: (i) Echinococcus genus, (ii) E. granulosus complex, and (iii) genetic variants within the E. granulosus complex. The relatively complicated task of E. granulosus complex speciation and genotyping is clearly simplified by mPCR, and this technique therefore represents a useful tool for routine practice.
► This is the first study on the taeniid species infecting the Portuguese population of Iberian wolf. ► Taeniid species detected are strongly related to the feeding habits of this top carnivore. ► First report of Taenia polyacantha and Echinococcus intermedius in the Iberian wolf. ► A genuine wild cycle for E. intermedius might persist between wolves and wild boars in this region.
Taeniid species represent relevant pathogens in human and animals, circulating between carnivorous definitive hosts and a variety of mammalian intermediate hosts. In Portugal, however, little is known about their occurrence and life cycles, especially in wild hosts. An epidemiological survey was conducted to clarify the role of the Iberian wolf as a definitive host for taeniid species, including Echinococcus spp. Wolf fecal samples (n = 68) were collected from two regions in Northern Portugal. Taeniid eggs were isolated through a sieving-flotation technique, and species identification was performed using multiplex-PCR followed by sequencing of the amplicons. Taenia hydatigena (in 11.8% of the samples), Taenia serialis (5.9%), Taenia pisiformis (2.9%), Taenia polyacantha (1.5%) and Echinococcus intermedius (Echinococcus granulosus ‘pig strain’, G7) (1.5%) were detected. This is the first study to characterize the taeniid species infecting the Portuguese Iberian wolf, with the first records of T. polyacantha and E. intermedius in this species in the Iberian Peninsula. Iberian wolves can be regarded as relevant hosts for the maintenance of the wild and synanthropic cycles of taeniids in Portugal.
Echinococcus intermedius; Taenia spp.; Iberian wolf; Portugal
Dirofilaria immitis and Angiostrongylus vasorum are both important potentially fatal canine nematodes with overlapping endemic areas, especially in Europe. The preadult and adult stages of both species are living in the Arteria pulmonalis and the right heart, and diagnostically detectable circulating parasite antigens have been demonstrated for both species. For the detection of D. immitis infections, a variety of commercial tests have been developed, however, they have not been evaluated for cross-reactions against circulating antigens of A. vasorum.
In this study, potential cross-reactions of sera from 16 dogs, which were experimentally infected with A. vasorum and which had circulating antigens as confirmed by a species-specific ELISA, were evaluated for the detection of A. vasorum antigen in six commercially available D. immitis test kits.
In three fast tests (Witness® Dirofilaria, SensPERT® Canine Heartworm, SNAP® 4Dx® Plus), all sera were negative. One fast membrane ELISA (SNAP® HTWM RT Test) was positive with four sera (25%), and one serum delivered a non-valid result twice. In the PetChek® HTWM PF Test, depending on the interpretation protocol, 5 or 8 dogs (31.2 – 50%) were positive. With the DiroCHEK®-ELISA, a single A. vasorum-infected dog (6.2%) tested positive.
Due to potential cross-reactions with A. vasorum in commercially available test kits for the detection of D. immitis antigen, the simultaneous use of highly specific diagnostic methods for the differentiation of these two canine heart worms is recommended.
Angiostrongylus vasorum; Dirofilaria immitis; Antigen detection; Cross-reactions; Dogs
Alveolar echinococcosis (AE) is caused by the metacestode stage of Echinococcus multilocularis. Differential diagnosis with cystic echinococcosis (CE) caused by E. granulosus and AE is challenging. We aimed at improving diagnosis of AE on paraffin sections of infected human tissue by immunohistochemical testing of a specific antibody.
We have analysed 96 paraffin archived specimens, including 6 cutting needle biopsies and 3 fine needle aspirates, from patients with suspected AE or CE with the monoclonal antibody (mAb) Em2G11 specific for the Em2 antigen of E. multilocularis metacestodes. In human tissue, staining with mAb Em2G11 is highly specific for E. multilocularis metacestodes while no staining is detected in CE lesions. In addition, the antibody detects small particles of E. multilocularis (spems) of less than 1 µm outside the main lesion in necrotic tissue, liver sinusoids and lymphatic tissue most probably caused by shedding of parasitic material. The conventional histological diagnosis based on haematoxylin and eosin and PAS stainings were in accordance with the immunohistological diagnosis using mAb Em2G11 in 90 of 96 samples. In 6 samples conventional subtype diagnosis of echinococcosis had to be adjusted when revised by immunohistology with mAb Em2G11.
Immunohistochemistry with the mAb Em2G11 is a new, highly specific and sensitive diagnostic tool for AE. The staining of small particles of E. multilocularis (spems) outside the main lesion including immunocompetent tissue, such as lymph nodes, suggests a systemic effect on the host.
Echinococcosis is a life-threatening disease in humans that is caused by the larval stages of the tapeworms Echinococcus multilocularis and Echinococcus granulosus. The eggs of the parasites are released with faeces of canids, and humans are aberrantly infected. In humans, the larval stages of the parasites cause tumour-like lesions mainly in the liver and the lungs. Precise diagnosis of the parasite responsible for human disease is of utmost importance since therapy regimens largely differ between cystic and alveolar echinococcosis. Diagnosis is based on serology, imaging and histology, the latter being the gold standard. However, conventional histology cannot always clearly identify the causative parasite because both parasites can cause human tissue to present similar features. Therefore, we have developed the monoclonal antibody Em2G11 and an immunohistological technique that allows a cheap and fast clear-cut diagnosis of E. multilocularis even on aspirates and small archived bioptic tissue samples. Furthermore, this technique disclosed an unknown feature of human alveolar echinococosis we called "small particles of E. multilocularis" (spems). We argue that these small particles represent micro-fragments of E. multilocularis and thus point to a new form of host-parasite interaction.
Taenia taeniaeformis and the related zoonotic cestode Echinococcus multilocularis both infect the water vole Arvicola terrestris. We investigated the effect of age, spatio-temporal and season-related factors on the prevalence of these parasites in their shared intermediate host. The absolute age of the voles was calculated based on their eye lens weights, and we included the mean day temperature and mean precipitation experienced by each individual as independent factors.
Overall prevalences of E. multilocularis and T. taeniaeformis were 15.1% and 23.4%, respectively, in 856 A. terrestris trapped in the canton Zürich, Switzerland. Prevalences were lower in young (≤ 3 months: E. multilocularis 7.6%, T. taeniaeformis 17.9%) than in older animals (>7 months: 32.6% and 34.8%). Only 12 of 129 E. multilocularis-infected voles harboured protoscoleces. Similar proportions of animals with several strobilocerci were found in T. taeniaeformis infected voles of <5 months and ≥5 months of age (12.8% and 11.9%). Multivariate analyses revealed strong spatio-temporal variations in prevalences of E. multilocularis. In one trapping area, prevalences varied on an exceptional high level of 40.6-78.5% during the whole study period. Low temperatures significantly correlated with the infection rate whereas precipitation was of lower importance. Significant spatial variations in prevalences were also identified for Taenia taeniaeformis. Although the trapping period and the meteorological factors temperature and precipitation were included in the best models for explaining the infection risk, their effects were not significant for this parasite.
Our results demonstrate that, besides temporal and spatial factors, low temperatures contribute to the risk of infection with E. multilocularis. This suggests that the enhanced survival of E. multilocularis eggs under cold weather conditions determines the level of infection pressure on the intermediate hosts and possibly also the infection risk for human alveolar echincoccosis (AE). Therefore, interventions against the zoonotic cestode E. multilocularis by deworming foxes may be most efficient if conducted just before and during winter.
Cestodes are unable to synthesize de novo most of their own membrane lipids, including cholesterol, and have to take them up from the host during an infection. The underlying molecular mechanisms are so far unknown. Here we report the identification and characterization of a novel gene, Emabp, which is expressed by larval stages and adults of the fox tapeworm Echinococcus multilocularis. The encoded protein, EmABP, displays significant homologies to apolipoprotein A-I binding protein (AI-BP) of mammalian origin and to metazoan YjeF_N domain proteins. Like mammalian AI-BP, EmABP carries an export-directing signal sequence which is absent in predicted AI-BP orthologs from the related flatworms Schistosoma japonicum and Schmidtea mediterranea. Using a specific antibody and immunoprecipitation techniques, we demonstrate that EmABP is secreted into the extraparasitic environment and into the hydatid fluid of in vitro-cultivated metacestode vesicles. Furthermore, we show that apolipoprotein A-I (apoA-I), a major constituent of cholesterol-transporting high-density lipoproteins, is present in hydatid fluid. By pulldown experiments, we demonstrate that recombinantly expressed, purified EmABP interacts with purified human apoA-I and is able to precipitate apoA-I from human serum. On the basis of these features and the suggested function of AI-BP in cholesterol transport in higher eukaryotes, we propose a role for EmABP in cholesterol and lipid uptake mechanisms of larval E. multilocularis.
Alveolar echinococcosis (AE) is a severe helminth disease affecting humans, which is caused by the fox tapeworm Echinococcus multilocularis. AE represents a serious public health issue in larger regions of China, Siberia, and other regions in Asia. In Europe, a significant increase in prevalence since the 1990s is not only affecting the historically documented endemic area north of the Alps but more recently also neighbouring regions previously not known to be endemic. The genetic diversity of the parasite population and respective distribution in Europe have now been investigated in view of generating a fine-tuned map of parasite variants occurring in Europe. This approach may serve as a model to study the parasite at a worldwide level.
The genetic diversity of E. multilocularis was assessed based upon the tandemly repeated microsatellite marker EmsB in association with matching fox host geographical positions. Our study demonstrated a higher genetic diversity in the endemic areas north of the Alps when compared to other areas.
The study of the spatial distribution of E. multilocularis in Europe, based on 32 genetic clusters, suggests that Europe can be considered as a unique global focus of E. multilocularis, which can be schematically drawn as a central core located in Switzerland and Jura Swabe flanked by neighbouring regions where the parasite exhibits a lower genetic diversity. The transmission of the parasite into peripheral regions is governed by a “mainland–island” system. Moreover, the presence of similar genetic profiles in both zones indicated a founder event.
Echinococcus multilocularis is a tapeworm of the red fox, which represents a considerable health threat to respectively infected humans. Main endemic areas are located in China, Siberia, and central Europe. Alarmed by an emerging or reemerging situation in Europe, the question of how the parasite gets spatially and temporally spread and transmitted becomes essential to prepare appropriate control programs. The question was tackled by using genetic data on a large sample size of E. multilocularis adult stage tapeworms, combined with geographical site location data input. The historically documented endemic area, represented by the northern Alpine arch, was shown to harbour the highest genetic richness and diversity, as compared to surrounding areas in northern and eastern Europe. The spatial and temporal spread of different E. multilocularis genotypes in Europe seems to be ruled by a founder event, linked to exportation of parasites from the central core to newly identified (western and eastern) areas or subregions, where these parasites could subsequently disseminate under geographical separation from the original foci.
Echinococcus multilocularis, the causative agent of zoonotic alveolar echinococcosis, can be controlled effectively by the experimental delivery of anthelminthic baits for urban foxes. Monthly baiting over a 45-month period was effective for long-lasting control. Trimonthly baiting intervals were far less effective and did not prevent parasite recovery.
Control; Echinococcus multilocularis; praziquantel; urbanization; vulpes; dispatch
Public information about prevention of zoonoses should be based on the perceived problem by the public and should be adapted to regional circumstances. Growing fox populations have led to increasing concern about human alveolar echinococcosis, which is caused by the fox tapeworm Echinococcus multilocularis. In order to plan information campaigns, public knowledge about this zoonotic tapeworm was assessed.
By means of representative telephone interviews (N = 2041), a survey of public knowledge about the risk and the prevention of alveolar echinococcosis was carried out in the Czech Republic, France, Germany and Switzerland in 2004.
For all five questions, significant country-specific differences were found. Fewer people had heard of E. multilocularis in the Czech Republic (14%) and France (18%) compared to Germany (63%) and Switzerland (70%). The same effect has been observed when only high endemic regions were considered (Czech Republic: 20%, France: 17%, Germany: 77%, Switzerland: 61%). In France 17% of people who knew the parasite felt themselves reasonably informed. In the other countries, the majority felt themselves reasonably informed (54–60%). The percentage that perceived E. multilocularis as a high risk ranged from 12% (Switzerland) to 43% (France). In some countries promising measures as deworming dogs (Czech Republic, Switzerland) were not recognized as prevention options.
Our results and the actual epidemiological circumstances of AE call for proactive information programs. This communication should enable the public to achieve realistic risk perception, give clear information on how people can minimize their infection risk, and prevent exaggerated reactions and anxiety.