A One-Health evaluation of the burden of cystic echinococcosis and its prevention costs: Case study from a hypo-endemic area in Italy.

An integrated model, based on a One Health approach, was implemented to estimate the epidemiological and economic outcomes of cystic echinococcosis (CE) in Veneto region, an hypo-endemic area of Northern Italy, and the costs for its prevention. Data and information needed to populate the model were retrieved from published literature, official statistics, expert opinions, or actively searched through data mining (i.e., Hospital and slaughterhouse data), when fundamental data were not available. Human-health and animal-health costs, both public and private, were considered. The overall impact of CE in the study area was estimated in an yearly cost of about 0.5 million €, due to an average of 19.5 human hospitalized cases and about 200 infected animals among cattle and sheep, per year. The human:animal costs ratio was about 8:1. Most of the infected animals were autochthonous, while the identification of an autochthonous source of the infection for the human cases was extremely difficult, and unlikely in most cases. No specific action resulted to be in place for human surveillance, while veterinary surveillance accounted for a yearly cost of about 22,000 €. Sheepherders were found to pay privately an overall amount of around 2000 € for the preventive treatment of their dogs every year, but the applied protocol proved to be sub-optimal. The source of most of the human cases was likely external to the study area, and their economic impact accounts for a cost that is far exceeding that of surveillance and preventive actions in place in the veterinary sector. Although autochthonous human cases appeared to be very rare, the strengthening of preventive actions and surveillance systems can reduce the risk of their increment.

Assessment of the global pattern of genetic diversity in Echinococcus multilocularis inferred by mitochondrial DNA sequences.

The aim of this review was to assess our current knowledge on phylogeography and global genetic structure of Echinococcus multilocularis populations originating from rodents, wild canid hosts, and human. Six bibliographic databases were searched from 1990 to 2017, identifying a total of 110 publications. The cytochrome c oxidase subunit 1 (cox1) and cytochrome b (cytb) sequences of E. multilocularis from Asia, Europe, and North Americas were analyzed to estimate the diversity and neutrality indices, and genetic differentiation. A total of 69 (cox1, 36.7%) and 16 haplotypes (cytb, 19.2%) were grouped into various geographical clades. A parsimonious haplotype network demonstrated a star-like feature with haplo-groups Em2 (Asia: 36%), Em105 (Eastern Tibetan plateau: 4.8%), Em46 (Europe: 9.1%), Em73, (Europe: 2.7%) and Em92 (North Americas: 4.3%) as the most common haplotypes. A relatively high level of genetic diversity was detected in rodent-derived E. multilocularis isolates (Haplotype diversity: 0.944), wild canids (Hd: 0.912), and human origin (Hd: 0.704). The highest number of haplotypes (n = 59) and the highest haplotype diversity (0.969) were identified in the Asian and European populations, respectively. Cladistic phylogenetic tree indicated the European clade has a sister relationship with the Asian clade. However, some North American haplotypes were assigned to the European clade together with haplotypes from Poland. The statistically significant Fst values indicated that E. multilocularis populations of Asian-European, Asian-North American, and European-North American origins were genetically differentiated (Fst: 0.22624 to 0.43059). An occurrence of distinct parasite populations suggests that E. multilocularis derived from glacial refugia have been plausibly sustained by indigenous hosts during the Pleistocene Epoch.

Structural and Immunodiagnostic Characterization of Synthetic Antigen B Subunits From Echinococcus granulosus and Their Evaluation as Target Antigens for Cyst Viability Assessment.

Background: Several tools have been proposed for serodiagnosis of cystic echinococcosis (CE), but none seems promising for cyst viability assessment. Antigens with stage-specific diagnostic value have been described, but few studies with well-characterized antigens and human serum samples have been performed. Antigen B (AgB) proteoforms hold promise as markers of viability, due to their differential stage-related expression and immunoreactivity. Methods: Four AgB subunits (AgB1, AgB2, AgB3, AgB4) were synthesized and structurally characterized. Based on the preliminary evaluation of the subunits by western immunoblotting and enzyme-linked immunosorbent assay (ELISA), AgB1 and AgB2 were further tested in two ELISA setups and extensively validated on 422 human serum samples. Results: All subunits showed a high degree of spontaneous oligomerization. Interacting residues within oligomers were identified, showing that both the N-terminal and C-terminal of each subunit are involved in homo-oligomer contact interfaces. No hetero-oligomer was identified. AgB1 and AgB2 ELISAs revealed different sensitivities relative to cyst stage. Of note, besides high specificity (97.2%), AgB1 revealed a higher sensitivity for active-transitional cysts (100% for CE1, 77.8% for CE2, 81.5% for CE3a, and 86.3% for CE3b) than for inactive cysts (41.7% for CE4 and 11.1% for CE5) and postsurgical patients (44%). Interestingly, 19 of 20 patients with spontaneously inactive cysts and 6 of 9 treated with albendazole >5 years earlier were negative on the AgB1 assay. Conclusions: The structural characterization of subunits provides insights into the synthetic antigen conformation. The stage-related sensitivity of synthetic AgB1 holds promise as part of a multiantigen setting and deserves further longitudinal evaluation as marker of cyst viability.