Large-scale survey of a neglected agent of sparganosis Spirometra erinaceieuropaei (Cestoda: Diphyllobothriidae) in wild frogs in China

Abstract

BackgroundIn China, frogs play an understudied role in the spread of human sparganosis (caused by the larval form of Spirometra). However, our knowledge about the prevalence of sparganum infection in frogs remains fragmented, and the taxonomic identification of the parasite is still controversial. Methodology/Principal findingsThe prevalence of sparganum infection in wild frogs was surveyed at 145 geographical locations from 28 of the 34 provinces/autonomous regions/municipalities in China for six years. The collected sparganum isolates from the different locations were subjected to molecular identification by a multiplex PCR assay and then were analysed with clustering analysis. In the survey, sparganum infection was found in 8 out of 13 of the collected frog species, and the most frequently infected species was Pelophylax nigromaculatus (the infection rate was up to 14.07%). Infected frogs were found in 80 of the 145 surveyed locations. The sparganum infection rates in the wild frogs in several regions of China were still high (above 10%), especially in South and Southwest China. A total of 72 spargana were selected for molecular identification, and the clustering analysis showed that sequences from the Chinese isolates were very similar to those identified as from Spirometra erinaceieuropaei. However, the taxonomy of the genus remains confused and further analysis is required. ConclusionsEating wild frogs is associated with considerable health risks in China. Several traditional Chinese folk remedies may increase the risk of infection. The sparganum isolates in China are most likely from S. erinaceieuropaei, but new studies, especially comprehensive morphological analyses, are needed in the future.

Sparganosis due to Spirometra sp. (Cestoda; Diphyllobothriidae) in captive meerkats (Suricata suricatta)

“…Our diagnosis was confirmed by integrated gross and histopathological, parasitological, and molecular findings. Despite the fact the meerkat has not been previously reported as paratenic hosts for Spirometra sp., sparganosis have been reported from a wide variety of vertebrate hosts, including amphibians, reptiles, bids, and mammals, including humans ( Bengtson and Rogers, 2001 ; Kondzior et al, 2018 ; Kuchta et al, 2020 ; Oda et al, 2016 ; Zhang et al, 2020 ). The varied clinical presentations and different outcomes of the reported cases may be associated with the location and intensity of infection by plerocercoids of Spirometra and co-morbidities.…”

First identification and molecular phylogeny of Sparganum proliferum from endangered felid (Panthera onca) and other wild definitive hosts in one of the regions with highest worldwide biodiversity

“…The PCR-product obtained was sequenced and firstly aligned with ClustalX (v2.0.12) with Spirometra and Sparganum sequences extracted from complete mitochondrial genomes available on GenBank and considered as reference genomes ( International Helminth Genomes Consortium, 2019 ). To get insight into an accurate phylogenetic analysis of our parasite linage we downloaded cox1 sequences form Asia, Africa, Europe and South America totalling 275 cox1 sequences ( Lavikainen et al, 2013 ; Zhang et al, 2017 , 2020 ; Jeon and Eom, 2019 ; Kołodziej-Sobocińska et al, 2019 ; Hong et al, 2020 ). After several sequence redundancy removal 42 cox1 sequences were retained.…”

“…Sparganosis cases are reported worldwide, but it has been predominantly diagnosed in Southeast Asia, mainly in China ( Dorny et al, 2009 ; Qiu and Qiu, 2009 ; Liu et al, 2015 ). Human sparganosis frequently occurs by consuming raw or undercooked meat of infected reptiles or amphibians, drinking water contaminated with copepods as well as direct contact with the skin of infected frogs or snakes ( Li et al, 2011 ; Liu et al, 2015 ; Oda et al, 2016 ; Okino et al, 2017 ; Zhang et al, 2020 ). Also, a case of human infection by adult of S. erinaceieuropaei has been reported in Vietnam ( Le et al, 2017 ).…”

“…In Asia, there are several studies of S. erinaceieuropaei lineages ( Zhang et al, 2016 ), particularly in wild frogs in China the prevalence is above 10% in some regions. ( Hong et al, 2020 ; Zhang et al, 2017 , 2020 ). Regarding Africa, there are molecular reports of findings of Spirometra sp.…”

Multispecies reservoir of Spirometra erinaceieuropaei (Cestoda: Diphyllobothridae) in carnivore communities in north-eastern Poland

“…The first intermediate host is a copepod (planktonic freshwater crustacean), in which coracidia develop into procercoid larvae (the first larval stage). When the infected copepod is swallowed by a second intermediate host, such as an amphibian or reptile [ 9 – 12 ], the procercoid larvae penetrate the intestinal tract and transform to plerocercoids (spargana), which then migrate and settle in other organs and tissues, such as subcutaneous connective tissue, the brain, lungs, spinal cord, urinary bladder or eye [ 13 – 20 ].…”