Morphological characterization of adult Fascioloides magna (Trematoda: Fasciolidae): first SEM report

Department of Pathobiology, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran.
Parasitology Research (Impact Factor: 2.1). 08/2011; 110(2):971-8. DOI: 10.1007/s00436-011-2582-2
Source: PubMed


Five adult Fascioloides magna specimens were recovered from the livers of naturally infected calves from Texas, USA. Scanning electron microscopy was used to study the morphological characteristics of the trematodes. These mature flukes measured 35-100 mm in length by 15-25 mm in width and had an oval dorsoventrally flattened body, with no anterior cone. The tegument was armed with sharp spines. Around the oral and ventral suckers, some of the spines were small, with a sharp point, while others had serrated edges with 15-22 sharp points. The surface of the oral sucker was covered by an interesting pattern of tegument, small dome-shaped and ciliated papillae. The ventral sucker showed a smooth surface and two unknown spine-like structures. There were fewer spines at the base of the genital pore than on other parts of the anterior end of the worm. At the anterior end of the ventral side, well-developed spines were observed, while at the posterior end of the ventral side, the spines were small, mostly with one or three points and blunted edges. At the posterior end of the dorsal side, the spines became progressively fewer, smaller, and shorter. Around the excretory pore, the tegument was folded, with no spines, and small groups of dome-shaped and ciliated papillae were present. The cirrus organ showed a smooth surface, with small pores on the dorsal side and small groups of tiny spines between the folds. The eggs measured 168 × 101 μm and had a protoplasmic appendage at the pole opposite the operculum. At the posterior end of the dorsal side, and toward the right, a pore with a very thin rim was present, which could be the terminus of Laurer's canal.

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    • "On the other hand, for roe deer the infection with a few flukes (less than 10 individuals) can be lethal [1]. The second category – “non-specific definitive hosts (dead-end hosts)” - is represented e.g. by moose (Alces alces), lama (Lama glama) and cattle (Bos taurus); these animals only exceptionally contribute to spreading of F. magna; the adult flukes can produce eggs, but these are trapped in liver pseudocysts not connected to the bile duct system [25-27]. Pathological impact on the “dead-end hosts” can differ. "
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    ABSTRACT: 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. 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. 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.
    BMC Veterinary Research 02/2014; 10(1):41. DOI:10.1186/1746-6148-10-41 · 1.78 Impact Factor