Recovery of Fascioloides magna (Digenea) population in spite of treatment programme? Screening of Galba truncatula (Gastropoda, Lymnaeidae) from Lower Austria

Development of a qPCR Duplex Assay for simultaneous detection of Fascioloides magna and Galba truncatula in eDNA samples: Monitoring beyond boundaries

Parasites constitute a significant economic burden and highly impact environmental, public, and animal health. The emergence of many parasitic diseases is environmentally mediated and they share the same biogeography with humans and both domestic and wild animals. American liver fluke, Fascioloides magna - a trematode parasite of domestic and wild ungulates - is an example of the anthropogenic introduction of an "invasive alien species" in Italy and Europe. Multiple introductions to Europe have led to the biogeographical expansion of the parasite across the Danube region mainly provided by the presence of suitable habitats for all hosts involved in the parasite's life cycle, human-assisted transport, and drastic environmental events such as flooding. In Italy, it was introduced and established in La Mandria Regional Park (LMRP) near Turin in 1865 along with imported wapitis (Cervus elaphus canadensis) from North America (Bassi, 1875), but with no reported expansion to the surrounding areas. LMRP isolated F. magna focus, poses an important threat of possible expansion since the enclosed area is vulnerable to occasional bidirectional passage of roe deer. Additionally, tributary rivers to the Po river system, traversing the enclosed area, could further bolster the possibility of such spread. In this study, we developed a duplex qPCR assay for F. magna and its principal intermediate host Galba truncatula optimized for testing eDNA samples to meet the needs for surveillance of the parasite. Moreover, we validated the developed assay in natura by testing samples derived from filtered water and sediments collected inside and outside LMRP's fenced-off area. Our findings for the first time demonstrate the presence of F. magna's eDNA outside the park's internal fenced-off area.

The giant liver fluke in Europe: A review of Fascioloides magna within cervids and livestock with considerations on an expanding snail-fluke transmission risk

The giant liver fluke, Fascioloides magna, common in North America and introduced into Europe in the 19th century, is an underappreciated model system for epidemiological studies on biological invasions, interactions with other native parasites and for health impact assessments within both definitive and intermediate snail host populations. Owing to its first contemporary appearance in Europe and then its subsequent spread, fascioloidosis has become a fluke-livestock/wildlife-snail combination of increasing interest for veterinarians, parasitologists and population geneticists. Here, we present a description of its recent epidemiology, biogeography and biology, inclusive of host species lists. Special emphasis is placed upon known definitive hosts of F. magna within Europe and considerations upon this fluke's local intermediate snail hosts. This helps us envisage plausible future epidemiological scenarios for further expansion across Europe, potentially even invasion into the UK. In line with others who draw attention upon needs for better systematic monitoring of putative risk-areas of fluke transmission, we close by highlighting why better surveillance of F. magna across continental Europe, and neighbouring territories, is justified.

Infectious Wildlife Diseases in Austria-A Literature Review From 1980 Until 2017

This literature review examines infectious wildlife disease research in Austria. We analyzed 226 research papers, published between 1980 and 2017. We determined that wildlife disease papers increased significantly from 0.8 ± 0.8 publications per year in the first decade (1980–1989) when compared to 2008–2017 with an average of 12.9 ± 4.1 publications per year. We illustrate information about the most investigated diseases and highlight the lack of research into certain wildlife pathogens. A special emphasis was given to diseases with zoonotic potential. The review showed that research focused on a few select species like the red fox (Vulpes vulpes), red deer (Cervus elaphus), and wild boar (Sus scrofa), all game species. Moreover, diseases affecting livestock and human health were seen more often. The review also found that only a low number of publications actually stated disease prevalence and confidence interval data. The reported diseases identified were classified according to their notifiable status and the distribution at the wildlife–human and wildlife–livestock interface. Furthermore, we try to argue why research into some diseases is prioritized, and why other diseases are underrepresented in current Austrian research. While spatiotemporal indicators could not be assessed due to the variability in methodologies and objectives of various studies, the information provided by this review offers the first comprehensive evaluation of the status of infectious wildlife disease research in Austria. Therefore, this study could assist investigators to identify further areas of priorities for research and conservation efforts and for wildlife management professionals to inform policy and funding strategies. With this review, we want to encourage research in the field of wildlife diseases in Austria to enhance current knowledge in the prevention of further loss in biodiversity and to find new measures to promote “One Health” on a global scale.

A new method for laboratory rearing of Galba truncatula, the intermediate host of Fasciola hepatica

In this study a relatively large and open top aquarium was designed, constructed and introduced as a suitable habitat for nutrition, growth and development as well as for egg laying and breeding of Galba truncatula under laboratory conditions. The soil and water used in the aquarium were collected from the locality in which the snails were collected. The aquarium was placed in a laboratory with temperature of 18-32 ºC and relative humidity of 22-37% respectively, according to the season. The artificial light was controlled by a light timer, giving 12 h of light and 12 h of darkness. The snails were fed with dried lettuce leaves, Cyperus alternifolius (aquatic plant), Spirulina (algae), Orthotrichum rupestre (moss) and cuttlebone (a supplementary source of calcium). Approximately five weeks after the start of study, there was evidence of reproduction and success in rearing of G. truncatula by the appearance of eggs and small snails (0.1-0.5 mm) in the aquarium. In conclusion, large scale laboratory rearing of G. truncatula is a feasible task. The method may be improved by balancing the temperature and relative humidity as well as by optimizing the soil type, the water quality and the type of food.

Genetic homogeneity of Fascioloides magna in Austria

The large American liver fluke, Fascioloides magna, is an economically relevant parasite of both domestic and wild ungulates. F. magna was repeatedly introduced into Europe, for the first time already in the 19th century. In Austria, a stable population of F. magna has established in the Danube floodplain forests southeast of Vienna. The aim of this study was to determine the genetic diversity of F. magna in Austria. A total of 26 individuals from various regions within the known area of distribution were investigated for their cytochrome oxidase subunit 1 (cox1) and nicotinamide dehydrogenase subunit 1 (nad1) gene haplotypes. Interestingly, all 26 individuals revealed one and the same haplotype, namely concatenated haplotype Ha5. This indicates a homogenous population of F. magna in Austria and may argue for a single introduction. Alternatively, genetic homogeneity might also be explained by a bottleneck effect and/or genetic drift.

Morphology and molecular study of Fascioloides magna – a growing threat to cervids (Cervidae) in Poland

Introduction: The giant liver fluke, Fascioloides magna, has spread across Europe over the years posing a serious threat to the Polish cervid population. Material and Methods: Macroscopic and histopathological studies of the liver of 22 roe deer (Capreolus capreolus), 10 red deer (Cervus elaphus), and 6 fallow deer (Dama dama) were performed. Species determination of the recovered liver flukes and eggs was performed by PCR protocol amplifying fragments of ribosomal DNA (ITS2), according to a standard method. Results: The presence of F. magna was confirmed in three (13.6%) roe deer, seven (70.0%) red deer, and two (33.3%) fallow deer. The fluke eggs were found only in the stools of five red deer and one fallow deer. Conclusion: This study presents detailed pathological and histopathological changes in the liver of wild Polish cervids, including roe deer, which were subjected to such study for the first time. The hepatic lesions typical for different stages of liver cirrhosis varied depending on the host species and stage of the disease.

Wherefrom and whereabouts of an alien: the American liver fluke Fascioloides magna in Austria: an overview

The giant liver fluke Fascioloides magna, an invasive species originating from North America, was recorded in Austria in the wild for the first time in 2000. Since then, various data concerning the epidemiology in snail intermediate hosts and cervid final hosts have been reported. Galba truncatula acts as snail intermediate host, and red deer, roe deer and fallow deer act as final hosts. G. truncatula is abundant throughout the region, especially along muddy shores of slow-flowing branches of the river system. Prevalence in deer (20-100 %) is much higher than in snails (0.03-0.2 %). Despite medical treatment of parts of the deer population, the parasite has successfully established itself on both sides of the Danube floodplain environments southeast of Vienna. Genetic analysis revealed that the infection of Austrian deer populations apparently originated from foci in the Czech Republic or from populations of Danube tributaries. Areas adjacent southwards, which will soon be joined through wildlife crossings, have not yet evidenced F. magna. Nonetheless, these environments are inhabited by host snails and deer and therefore constitute suitable habitats for F. magna. Invading alien parasites not only threaten native individual hosts but also influence host populations, thus potentially also modifying parasite communities and interactions. The host range of F. magna includes a variety of potential hosts, notably other Lymnaeidae as potential intermediate hosts and various ungulates, including sheep and cattle, as final hosts. Because eradication after medical treatment was unsuccessful, and due to the risk of further spread of the parasite into unaffected regions, enhanced control strategies need to be developed. We recommend assessment of introduction pathways and dispersal, continuous monitoring of host abundance and distribution and the prevalence of flukes in intermediate and final hosts, as well as coordinated and concerted actions with neighbouring countries. This strategy could help to reduce potential negative impacts of this and other invasive parasites on host populations in Europe.

Highland cattle and Radix labiata, the hosts of Fascioloides magna

Background

Fascioloides magna is a pathogenic fluke introduced to Europe ca 140 years ago. As it is spreading over the continent, new intermediate and definitive hosts might be involved in transmission of the parasite. In Europe, several studies reported potential new intermediate snail hosts (Radix spp.) for F. magna, and also several cases of fascioloidosis of wild and domestic animals were published. However, the data based on molecular and histological analyses confirming these findings remained unreported. This study aims to refer to unique findings of F. magna in European snails and domestic animals (the first observation in the Czech Republic in the last 30 years) and demonstrate the use of molecular techniques in determination of F. magna.

Results

Two snails of R. labiata naturally infected with F. magna were found; mature cercariae and daughter rediae were observed. Maturity of cercariae was checked by histological methods, however, their ability to encyst was not confirmed. Co-infection of F. magna and Fasciola hepatica in the liver of two highland cattle bulls was proved. Adult fasciolid flukes producing eggs were found in the liver pseudocysts (F. magna) and the bile ducts (F. hepatica). Identification of intermediate hosts, intramolluscan stages, adult flukes and eggs was performed by sequencing the ITS2 region. Connection of F. magna pseudocysts with the gut (via the bile ducts) was not confirmed by means of histological and coprological examinations.

Conclusions

For the first time, Radix labiata was confirmed as the snail host for F. magna under natural conditions and, together with the finding of F. magna infection in cattle, we can expect further transmission of F. magna from wildlife to livestock in localities shared by these hosts.