ABSTRACT
Objective: To investigate the prevalence of cercarial trematode infection in snails and to examine the reconstruction of the phylogenetic relationship to explain the molecular system of cercarial stage trematodes to estimate the infection rate of in the definite host from the Chao-Phraya Basin. Methods: The snails were collected from 10 provinces of the Chao-Phraya Basin, Thailand by stratified sampling method. The snails were examined for cercarial infection by the crushing method. All DNA specimens were amplified with internal transcribed spacer 3 (ITS3) and ITS4 primer based on PCR technique. The sequence data were aligned and used to reconstruct the phylogenetic tree by unweighted pair-group method with arithmetic means with 10 000 bootstraps. Results: The overall rate of cercarial infection was found to be 5.90%(122/2 067). Snails in the family Thiaridae were found to be in the highest prevalence followed by Lym-naeidae, Bithyniidae, Planorbidae, Viviparidae, and Ampullariidae, respectively, while the Buccinidae family (Clea helena) did not reveal any infections. The frequently found species of cercariae were parapleurolophocercous cercariae, cercariae and megarulous cercariae. The monophyletic tree separated the snails into five groups comprised of Heterophyidae, Strigeidae, Lecithodendriidae, Philophthalmidae and Echinostomatidae using the sequence of Angiostrongylus cantonensis as an out-group. Conclusions: This study was the first to report on cercarial infection in the Chao-Phraya Basin, Thailand. This revealed that a high variety of freshwater snails were infected by cercariae stage trematodes with a high prevalence. The sequence data of ITS2 can be used to investigate the phylogenetic relationships of trematodes at the family level and in each clade of different families separated by the definitive hosts.
ABSTRACT
Objective: To investigate the prevalence of cercarial trematode infection in snails and to examine the reconstruction of the phylogenetic relationship to explain the molecular system of cercarial stage trematodes to estimate the infection rate of in the definite host from the Chao-Phraya Basin. Methods: The snails were collected from 10 provinces of the Chao-Phraya Basin, Thailand by stratified sampling method. The snails were examined for cercarial infection by the crushing method. All DNA specimens were amplified with internal transcribed spacer 3 (ITS3) and ITS4 primer based on PCR technique. The sequence data were aligned and used to reconstruct the phylogenetic tree by unweighted pair-group method with arithmetic means with 10. 000 bootstraps. Results: The overall rate of cercarial infection was found to be 5.90% (122/2. 067). Snails in the family Thiaridae were found to be in the highest prevalence followed by Lymnaeidae, Bithyniidae, Planorbidae, Viviparidae, and Ampullariidae, respectively, while the Buccinidae family (Clea helena) did not reveal any infections. The frequently found species of cercariae were parapleurolophocercous cercariae, cercariae and megarulous cercariae. The monophyletic tree separated the snails into five groups comprised of Heterophyidae, Strigeidae, Lecithodendriidae, Philophthalmidae and Echinostomatidae using the sequence of Angiostrongylus cantonensis as an out-group. Conclusions: This study was the first to report on cercarial infection in the Chao-Phraya Basin, Thailand. This revealed that a high variety of freshwater snails were infected by cercariae stage trematodes with a high prevalence. The sequence data of ITS2 can be used to investigate the phylogenetic relationships of trematodes at the family level and in each clade of different families separated by the definitive hosts.
ABSTRACT
Opisthorchiasis caused by Opisthorchis viverrini (O. viverrini) remains as medically important problem in Thailand especially in the north-eastern part. Infection with this parasite can lead to cholangiocarcinoma improvement. The highest prevalence of O. viverrini infection has been found in the Northeast Thailand and is associated with the high incidence rate of cholangiocarcinoma. To complete the life cycle of O. viverrini, the freshwater snails namely Bithynia funiculata, Bithynia siamensis siamensis and Bithynia siamensis goniomphalos (B. s. goniomphalos) are required to serve as the first intermediate host. Within these snails group, B. s. goniomphalos is distributed concisely in northeast Thailand and acts as the majority snail that transmitted the opisthorchiasis in this region. This study described the information of B. s. goniomphalos which research are needed for understanding the biology, distribution, transmission and factors influencing on the infection of the snail vector of this carcinogenic parasite.
ABSTRACT
Opisthorchiasis caused by Opisthorchis viverrini (O. viverrini) remains as medically important problem in Thailand especially in the north-eastern part. Infection with this parasite can lead to cholangiocarcinoma improvement. The highest prevalence of O. viverrini infection has been found in the Northeast Thailand and is associated with the high incidence rate of cholangiocarcinoma. To complete the life cycle of O. viverrini, the freshwater snails namely Bithynia funiculata, Bithynia siamensis siamensis and Bithynia siamensis goniomphalos (B. s. goniomphalos) are required to serve as the first intermediate host. Within these snails group, B. s. goniomphalos is distributed concisely in northeast Thailand and acts as the majority snail that transmitted the opisthorchiasis in this region. This study described the information of B. s. goniomphalos which research are needed for understanding the biology, distribution, transmission and factors influencing on the infection of the snail vector of this carcinogenic parasite.