DNA Barcode Identification of Freshwater Snails in the Family Bithyniidae from Thailand

Abstract

Freshwater snails in the family Bithyniidae are the first intermediate host for Southeast Asian liver fluke (Opisthorchis viverrini), the causative agent of opisthorchiasis. Unfortunately, the subtle morphological characters that differentiate species in this group are not easily discerned by non-specialists. This is a serious matter because the identification of bithyniid species is a fundamental prerequisite for better understanding of the epidemiology of this disease. Because DNA barcoding, the analysis of sequence diversity in the 5’ region of the mitochondrial COI gene, has shown strong performance in other taxonomic groups, we decided to test its capacity to resolve 10 species/ subspecies of bithyniids from Thailand. Our analysis of 217 specimens indicated that COI sequences delivered species-level identification for 9 of 10 currently recognized species. The mean intraspecific divergence of COI was 2.3% (range 0-9.2 %), whereas sequence divergences between congeneric species averaged 8.7% (range 0-22.2 %). Although our results indicate that DNA barcoding can differentiate species of these medically-important snails, we also detected evidence for the presence of one overlooked species and one possible case of synonymy.

Cercarial trematodes in freshwater snails from Bangkok, Thailand: prevalence, morphological and molecular studies and human parasite perspective

“…Previous studies have reported approximately 30 species of eight freshwater snail families infected by trematode cercariae in Thailand: Ampullariidae, Bithyniidae, Lymnaeidae, Nassariidae, Pachynidae, Planorbidae, Thiaridae and Viviparidae (Dechruksa et al, 2007;Ukong et al, 2007;Chuboon and Wongsawad, 2009;Chontananarth and Wongsawad, 2013;Krailas et al, 2014;Kulsantiwong et al, 2015;Namsanor et al, 2015;Anucherngchai et al, 2016Anucherngchai et al, , 2017Veeravechsukij et al, 2018), these studies have revealed 15 morphological types of trematode cercariae, such as amphistome, echinostome, gymnocephalous, parapleurolophocercous, pleurolophocercous and xiphidiocercariae, which belong to families of human intestinal flukes (Chai et al, 2009;Hung et al, 2013;Chai, 2019). Moreover, nine families of brackish-water snails have been observed to carry cercariastage digenean trematodes (Sri-Aroon et al, 2004).…”

Differential Protein Expression in the Hemolymph of Bithynia siamensis goniomphalos Infected with Opisthorchis viverrini

“…In the endemic regions of northeast Thailand, there is a high prevalence of O . viverrini infection in humans and fish, although the prevalence of infected Bithynia snails is low [6–10]. It has been found that the level of O .…”

Proteomic profile of Bithynia siamensis goniomphalos snails upon infection with the carcinogenic liver fluke Opisthorchis viverrini

“…Because of the difficulty in breeding snails in the laboratory, wild snails were collected from the field and checked for parasitic infections. Uninfected snails were infected with O. viverrini eggs and the infection was monitored by cercarial emission and examination of hatched eggs in the snail faeces twice each week over an 8 week period as described previously [9, 30]. …”

“…The plastic containers were checked daily and dead snails were removed. Each snail was subsequently examined for trematode infection by testing cercarial shedding and examination of hatched eggs in the snail faeces twice within a week as described previously [9, 30]. …”