Development of a real-time PCR assay with fluorophore-labelled hybridization probes for detection of Schistosoma mekongi in infected snails and rat feces.

Schistosoma mekongi, a blood-dwelling fluke, is a water-borne parasite that is found in communities along the lower Mekong River basin, i.e. Cambodia and Lao People's Democratic Republic. This study developed a real-time PCR assay combined with melting-curve analysis to detect S. mekongi in laboratory setting conditions, in experimentally infected snails, and in fecal samples of infected rats. The procedure is based on melting-curve analysis of a hybrid between an amplicon from S. mekongi mitochondrion sequence, the 260 bp sequence specific to S. mekongi, and specific fluorophore-labelled probes. This method could detect as little as a single cercaria artificially introduced into a pool of 10 non-infected snails, a single cercaria in filtered paper, and 2 eggs inoculated in 100 mg of non-infected rat feces. All S. mekongi-infected snails and fecal samples from infected rats were positive. Non-infected snails, non-infected rat feces, and genomic DNA of other parasites were negative. The method gave high sensitivity and specificity, and could be applied as a fast and reliable tool for cercarial location in water environments in endemic areas and for epidemiological studies and eradication programmes for intermediate hosts.

Distribution of Pila polita in a southern province of Thailand.

This field study investigated the distribution of the freshwater snails of the family Ampullariidae in 18 provinces of Thailand. The introduced Pomacea canaliculata has wide distribution in the studied provinces. Pila angelica, P. ampullacea and P. pesmei still have limited distribution. Pila polita, which is absent in the south, now can be found in Phangnga, a southern province of Thailand. Moreover, P. polita is currently used as a traditional medicine of the local people for the treatment of a skin disease.

Maternal influence on the use of impregnated bednets in the protection of infantile malaria.

A cross-sectional survey of 184 mothers or caretakers was undertaken to investigate the effect of socio-behavioral background on decision making in relation to the use of impregnated bednets to prevent malaria for their children in Ratchaburi Province, Thailand. It was found that most mothers had knowledge of the cause, transmission and prevention of malaria. They perceived susceptibility and severity of malaria as a risk to their children, which might even cause death. They also perceived and had positive attitudes toward impregnated bednets as a protection for their children. Three-quaters (76.4%) of them used impregnated bednets regularly to protect their children whereas one-quarter (23.6%) used infrequently and few never used. Bivariate analysis showed that the use of impregnated bednets was significantly related to the factors such as knowledge of malaria prevention, perception of benefits of the use, the receipt of information about the impregnated bednets from malaria workers.

Survival of beta and gamma races of Neotricula aperta snail intermediate hosts of Schistosoma mekongi in raw waters.

Beta and gamma races of Neotricula aperta were exposed to naturally raw waters of the Sirindhorn reservoir, Mun River and Mekong River in laboratory conditions and non supplement on food. Snails of two races could withstand well in variable qualities of water within 48 hours. The survival rates of N. aperta in three sources of raw water were 100% for the beta race and 97 to 100% for the gamma race.