Materials and methods
1. Collection of adult A. cantonensis from captive rats
Rats were collected from Tha Pho sub-district, Phitsanulok during May 2010 to February 2011. Traps were baited with banana and the trapped rats were brought every morning to laboratory for examination. They were rats were euthanized by placing the trap into the plastic box containing a cotton wool soaked with diethyl ether. The thoraxes were opened to remove the lungs and hearts which were placed in Petri dishes containing normal saline. Female A. cantonensis worms were identified by their Barber pole pattern and the long vagina with no projection at tip of the tail. The worms were collected and fixed in 10% formalin.
2. Collection of 3rd stage larvae of A. cantonensis from giant African land snails
Giant African land snails were collected from Phitsanulok during rainy season (May-August 2010 ) temporarily maintained in a plastic box and fed lettuce leaf. The hard shell of each land snails was removed. The snails were chopped into small pieces, blended and then incubated with 1% pepsin solution, at 37℃ for 1 hour. The 3rd stage larvae were isolated by the Baermann techniques. The apparatus was constructed a glass funnel connected to a short piece of rubber tubing at the outlet. Several layers of gauze were laid over a wire mesh at the bottom surface of the funnel. With the outlet closed, the digested solution was poured into the funnel until the fluid level touched the wire mesh. The apparatus was left standing for 30 minutes to allow larvae migrate into the rubber tube. At the end of this period, the fluid containing mainly enriched L3 larvae was released into
a Petri dish. They were morphologically identified using the following criteria: (1) the body is long, thin and delicate; (2) It has two chitinous rods at the anterior end and the cuticle possesses delicate transverse striations; (3) the tail is cone- shaped, slightly curved and pointed.