On the geographic genetic variants of the cestode Echinococcus multilocularis with reference to the original descriptions from Bowles et al. (1992) and Bowles and McManus (1993), and their use

Alveolar echinococcosis, caused by the larval stages of the tapeworm Echinococcus multilocularis (Leuckart, 1863), is of increasing concern in the northern hemisphere. Most cases of alveolar echinococcosis (excluding Alaska) appear to be linked with European and Asian genotypes that highlight the need for a more precise delimiting of their actual distribution and tracing historical episodes of their translocations and introductions into new areas. We have herein summarized previous available research studies, which mentioned firstly described geographic M1/M2 variants of E. multilocularis using molecular tools (established by sequencing of mitochondrial genes cox1, 366 bp and nad1, 471 bp), in an attempt to consolidate their correct affiliations with the geographic origin in sense of the original description from the early 1990´s. Since 2009, inverted designations (M1 named as M2 and vice versa) are being prevailing in research literature (we found ten erroneous vs. three correct classifications) that might bias genetic interpretation of comparative data in specific cases. When comparing M1/M2 profiles to those obtained from mitochondrial evidences over the last decades, the phylogenetic analysis revealed that the M1 strain (originally described from China, Alaska, North America) grouped with the Asian clade of E. multilocularis more recently established, whereas the M2 strain (described from the German vole) had a specific structure, in cox1 clustering with the North American clade. It is presumed that events of intercontinental expansion and isolation covering glacial and interglacial periods during the late Pleistocene have likely accounted for the transmission of this discrete genotype from Beringia into endemic area of western and central Europe via circumpolar movements of foxes.

Worldwide literature on epidemiology of human alveolar echinococcosis: a systematic review of research published in the twenty-first century

PURPOSE

Human alveolar echinococcosis (AE) is a potentially lethal zoonosis caused by the cestode Echinococcus multilocularis. The aim of this systematic review is to establish a comprehensive global AE literature overview taking into account the epidemiologically relevant AE research of the twenty-first century.

METHODS

We systematically searched the global literature published from 2001 through 2018 via MEDLINE, EMBASE, the Russian databases eLIBRARY.RU, CyberLeninka, the Chinese databases CNKI, VIP, Journals.

RESEARCH

ac.ir (Farsi language-based), Jordan E-Library (Arab language-based) and supplementary Google Scholar, in accordance with the PRISMA guidelines. QGIS software was used for the mapping of the affected countries.

RESULTS

We have listed 154 relevant publications in the final literature synopsis in consideration of our quality assessment. Including non-autochthonous cases, human AE was reported in 36 countries within the northern hemisphere from 2001 to 2018. The first publication of AE in Tajikistan, Pakistan, South Korea, Belgium, the Netherlands, Slovakia, Hungary, Lithuania, Latvia, Slovenia and Morocco occurred in this century; further first cases in Taiwan, Thailand, and Denmark were considered to be non-autochthonous by the authors. The highest total case numbers (n ≥ 100 in a single article) were reported in France, Germany, Switzerland, Poland, and Lithuania, including China and Kyrgyzstan with by far the highest prevalence figures.

CONCLUSIONS

Our paper emphasises the increasing spread of reported cases and the rise in its numbers in the literature of the twenty-first century, especially in western, northern and eastern Europe, as well as in central Asia. Epidemiological studies on human infections are lacking in many parts of the world.

Molecular identification of cystic echinococcosis in humans and pigs reveals the presence of both Echinococcus granulosus sensu stricto and Echinococcus canadensis G6/G7 in the hyperendemic focus of the Republic of Moldova

Cystic echinococcosis is caused by the parasitic species of the complex Echinococcus granulosus sensu lato. This disease is hyperendemic in the Republic of Moldova. Recent molecular analyses have revealed the exclusive presence of E. granulosus sensu stricto in sheep and cattle. Previous reports of prevalence in pigs suggest the potential presence of Echinococcus canadensis G6/G7, as this species is also reported in neighboring countries. The presence of cystic echinococcosis in pigs was specifically monitored at the slaughterhouse. In the meantime, human cases were genotyped for the first time. E. canadensis G6/G7 was identified in all ten pigs infected by E. granulosus s.l. One human case of infection by E. canadensis G6/G7 was also identified, while E. granulosus sensu stricto was found to be the cause for the 13 others. The description of one human case of E. canadensis G6/G7 has confirmed its zoonotic impact in the country. Future studies will be needed to estimate the relative proportion and distribution of both parasitic species in Moldova.

Prevalence of abdominal cystic echinococcosis in rural Bulgaria, Romania, and Turkey: a cross-sectional, ultrasound-based, population study from the HERACLES project

BACKGROUND

Cystic echinococcosis is a neglected zoonotic infection that is distributed worldwide and prioritised by WHO for control efforts. The burden of human cystic echinococcosis is poorly understood in most endemic regions, including eastern Europe. We aimed to estimate the prevalence of abdominal cystic echinococcosis in rural areas of Bulgaria, Romania, and Turkey.

METHODS

We did a cross-sectional ultrasound-based survey that recruited volunteers from 50 villages in rural areas of Bulgaria, Romania, and Turkey. These villages were in provinces with annual hospital incidence of cystic echinococcosis within the mid-range for the respective countries. All people who attended a session were allowed to participate if they agreed to be screened. Abdominal ultrasound screening sessions were hosted in public community structures such as community halls, primary health-care centres, schools, and mosques. Lesions were classified using an adapted WHO classification. We reported the prevalence of abdominal cystic echinococcosis adjusted by sex and age through direct standardisation, using the country's rural population as a reference.

FINDINGS

From July 1, 2014, to Aug 3, 2015, 24 693 individuals presented to screening sessions and 24 687 underwent ultrasound screening. We excluded a further six indivduals due to missing data, leaving 24 681 people in our analysis. Abdominal cystic echinococcosis was detected in 31 of 8602 people screened in Bulgaria, 35 of 7461 screened in Romania, and 53 of 8618 screened in Turkey. The age and sex adjusted prevalence of abdominal cystic echinococcosis was 0·41% (95% CI 0·29-0·58) in Bulgaria, 0·41% (0·26-0·65) in Romania, and 0·59% (0·19-1·85) in Turkey. Active cysts were found in people of all ages, including children, and in all investigated provinces.

INTERPRETATION

Our results provide population-based estimates of the prevalence of abdominal cystic echinococcosis. These findings should be useful to support the planning of cost-effective interventions, supporting the WHO roadmap for cystic echinococcosis control.

FUNDING

European Union Seventh Framework Programme.

The echinococcoses in Asia: The present situation

Human alveolar and cystic echinococcosis, caused by the accidental ingestion of eggs of the tapeworms Echinococcus multilocularis and Echinococcus granulosus sensu lato, respectively, are endemic in Asia. Various Echinococcus species are maintained in domesticated and/or wild mammals through predator-prey interactions. Molecular analysis is used to help differentiate infecting parasite species and genotypes, with the goal of better understanding parasite life cycles in order to aid in the planning and implementation of control programs. This paper discusses the various echinococcoses in Asia, with limited reference to neighboring areas, including parts of Central Asia, Russia, Europe and North America.