Experimental platynosomosis: Characterization of parasite development in the mouse model

Platynosomum illiciens (Trematoda: Dicrocoeliidae) in a hybrid marmoset (Callithrix sp.) in the Municipality of Seropédica, RJ, Brazil – Case report

“…All sequences, with the exception of a single nucleotide polymorphism (SNP) observed in one of the sequences obtained from an experimentally infected mouse, were identical. Those results provided definitive evidence that P. illiciens can naturally infect felines and non-human primates as well as rodents experimentally, corroborating the findings of earlier morphological studies (Pinto et al, 2015(Pinto et al, , 2017. Importantly, the sequencing data demonstrated that Platynosomum infections in cats in the Americas and Asia are caused by the same parasite, substantiating the proposal of Rodrigues (1963), for the recognition of P. fastosum and P. illiciens as synonyms.…”

“…The morphological data, obtained for the adult specimens of P. illiciens examined herein, were compared (Table 1) with the values provided for proposed species of Platynosomum, recorded by Brazilian researchers, naturally infecting felids and birds (Travassos, 1944), or from non-human primates Pinto et al, 2017). In addition, we included morphological data registered in mice (Mus musculus) artificially infected with P. illiciens (Pinto et al, 2015). The results of those comparisons provided support for the proposition of Pinto et al ( 2017) that the parasites employed in the description of the species P. amazonensis and P. marmoseti were most likely not fully developed.…”

“…Although extensive morphological variability was reported for specimens of P. illiciens observed in hosts with natural (Travassos, 1944) or experimental infections (Pinto et al, 2015), factors such as parasite age, the precise Trematoda in primate location in the biliary system and the fixation technique used may influence the dimensions of the internal structures used for specific morphological diagnosis. For those reasons, it is of value to consider that such morphological variations may explain the various reports of different species of Platynosomum in animals Sitko, 1998;Pinto et al, 2016), when, in fact, based on molecular analyses they were most likely the same species (Pinto et al, 2018).…”

Molecular phylogeny provides new insights on the taxonomy and composition of Lyperosomum Looss, 1899 (Digenea, Dicrocoeliidae) and related genera

“…One of the main problems in the systematics of Lyperosomum and the Dicrocoeliidae as a whole is the insufficient knowledge of the extent of the intraspecific morphological variability. This variability is associated in part with the crowding effect which can be quite pronounced due to the parasitism in a limited space such as the gall bladder and bile ducts (e.g., Tkach and Bray, 1995; Pinto et al, 2015, 2017). In addition, these flukes grow continuously throughout their lives, and their anatomical features undergo partial changes including the size and proportions of the gonads (Macko, 1968; Sitko, 1994, 1995).…”

Treatment of primate platynosomosis: A word of caution about the use of praziquantel in marmosets

“…The correlation between worm burden and FEC is not absolute, since there are methodological and biological (eg, host sex and previous immune status) variations, which may even explain the different outcomes observed between M3 (survivor), M4, and M5 that presented similar initial FEC. In this sense, the use of mice as a model in experimental platynosomosis may be an interesting alternative, 32 considering that P. illiciens presents low specificity in relation to the vertebrate host 4,33 and that aspects of parasite biology, disease and prognosis are similar in different captive wild or domestic animals. However, attempts at treatment in naturally infected animals have generally been more common and justified by the difficulty of maintaining the cycle of Platynosomum spp.…”