Multiplex PCR assay for discrimination of Centrocestus caninus and Stellantchasmus falcatus

The prevalence of cercarial infection and development of a duplex PCR for detection of the cercarial stage of Haplorchis taichui and H. pumilio in first intermediate hosts from Chai Nat province, Thailand

This study aimed to investigate the prevalence of cercarial infections in freshwater snails collected from the Chai Nat province of Central Thailand. Moreover, we aimed to develop a duplex PCR technique, using the ITS2 and candidate MT-ND1 gene, to determine the dissemination of H. taichui and H. pumilio, respectively. Six types of cercariae were discovered with an overall prevalence of 4.71% (59/1,252). The parapleurolophocercous cercariae were demonstrated to be the dominant type, infecting only Melanoides tuberculata snails. The duplex PCR was optimized for specific amplification of ITS2 for H. taichui (115 bp) and MT-ND1 for H. pumilio (335 bp). Both specific primers confirmed the specificity of the duplex PCR reaction, with no cross-reactivity with other heterophyids or related species. In addition, this duplex PCR could be used to detect co-infection at a concentration of 3.0 ng/µL. For the molecular identification, 9 of 22 parapleurolophocercous cercaria specimens in Chai Nat province generated the specific DNA fragment of H. pumilio. These results proved that the MT-ND1 gene is a species-specific method for heterophyid detection and provides a rapid method for identification based on larval and adult stages of H. taichui and H. pumilio in their intermediate and/or definitive hosts in the infected area.

Echinostoma revolutum: Development of a high performance DNA-specific primer to demonstrate the epidemiological situations of their intermediate hosts

Echinostomiasis caused by the Echinostoma group, in particular E. revolutum are a significant problem for both humans and other animals. This group has a large number of morphological similarities that are difficult and time-consuming to identify. The present study aimed to develop high-performance tools for the detection of the prevalence of E. revolutum and to reveal the prevalence of E. revolutum infections in intermediate snail hosts in Lopburi province, Thailand. The snail specimens were collected by stratified sampling method and examined to collect trematodes in the larval stage. The specific primer was manually designed and based on 18 s rDNA and verified the specificity and sensitivity for use as an identification tool to compare with classical method, constructed by epidemic mapping. The overall prevalence value of E. revolutum was found to be 16.26%. Tha Luang district had the highest prevalence (70.14%), followed by Chai Badan, Phatthana Nikhom, Tha Wung, Ban Mi, Khok Samrong, Nong Muang and Sa Bot at 42%, 25.14%, 2.52%, 1.73%, 2%, 1.33% and 0.40%, respectively. With regard to the specific primer, it can amplify both cercarial and metacercarial DNA (90 pg/μl.) and discriminated E. revolutum from its hosts, other trematodes and other echinostome larvae with no cross-reactions. Therefore, the developed specific primer can be used as a species-specific identification tool with a high degree of sensitivity and specificity. Consequently, this data is important for monitoring the outbreak of E. revolutum. It can be applied for initiating surveillance programs of snail-borne diseases in both medical and veterinary studies.