The natural first intermediate host of Paragonimus siamensis (Miyazaki and Wykoff, 1965) in Thailand.

The first intermediate host of six-known the Paragonimus species in Thailand had not been found until the Filopaludina (Siamopaludina) martensi martensi snail was discovered to maintain the cercariae of a Paragonimus species. An extensive study examined cercarial development through to adult worms by infecting 3 genera of 7 crab species with penetration of cercariae and feeding of snails containing such cercariae. These crabs provided many metacercariae which were fed to cats and bandicoots. The animals gave many Paragonimus adult worms which were characterized as Paragonimus siamensis by the following criteria: 6-lobed ovary and cuticular spines in groups. It is concluded that the Filopaludina martensi martensi snail is a susceptable natural first intermediate host of P. siamensis. Second intermediate hosts Somanniathelphusa brandti, S. sexpunctatum and S. bangkokensis were experimentally infected; prior to this study only S. germaini and S. dugasti had ever been naturally infected with metacercariae of this species.

Comparative study of different doses of mebendazole in hookworm infection.

Sixty six children (40 males, 26 females) aged from 4 to 14 years with hookworm infection were treated with mebendazole. Thirty one and 35 children were treated with mebendazole 300 mg single dose and 600 mg conventional regimen respectively. Stool examination by Kato-Katz technique were done for 3 consecutive days before treatment and on day 14-16, 21-23 after treatment. The cure rate with 300 mg mebendazole was 16.1% with 90.9% egg reduction while 600 mg mebendazole gave 91.4% cure rate with 99.5% egg reduction. No side effects were observed in all children. Four hundred and six adult worms were identified, 99% were Necator Americanus, 0.5% Ancylostoma duodenale and 0.5% Ancylostoma ceylanicum.

The route of migration of Paragonimus siamensis Miyazaki & Wykoff, 1965 in the white rat.

After they were ingested, the metacercariae of Paragonimus siamensis excysted in the stomach, penetrated through the stomach wall and the first 3 centimetres of small intestinal wall into the abdominal cavity, then penetrated into abdominal muscle. The worms stayed in abdominal muscle for about one week, then appeared again in the abdominal cavity before entering the pleural cavity and lungs; they also appeared in thoracic muscle, diaphragm, liver, and muscle of foreleg. The worm's size increased steadily until worm reaches sexual maturity then body size increased slowly. Genital primordia could be recognized at one week, of the reproductive system vitellaria were the last to appear at week 5, and eggs were first seen in the 7-week-old worms.