Qualitative and quantitative analysis of organochlorine insecticide residues were conducted in water, sediment, aquatic plants and animals from 3 freshwater reservoirs. Ninety water samples, 90 sediment samples, 397 aquatic plants samples and 121 aquatic animals samples were collected during March-April and August-September 1989. There were about 14 kinds of aquatic plants, such as water hyacinth, water lettuce, algae and water lilly etc. Aquatic animals are fish, shrimps and snails, but most of them are fish. They are striped snake-head fish, carp and catfish etc. Total samples of 698 were analyzed by using gas chromatographic techniques at Agricultural Toxic Substances Division. The results indicated that 5 kinds of insecticides were found in most samples. They were lindane, heptachlor, aldrin, dieldrin, DDT and derivatives. Dieldrin was detected at higher concentration and found in all samples. The residue level of dieldrin ranged from 0.01-0.12 ppb in water, 0.005-0.036 ppm in sediment, 0.001-0.138 ppm in aquatic plants and 0.001-0.037 ppm in aquatic animals respectively. The accumulation of dieldrin residue in water and aquatic plant samples from all reservoirs are not different but the level of dieldrin residue in sediment samples from Bueng Boraphed is higher than the other 2 reservoris. However the levels of dieldrin residue in sediment, aquatic plant and aquatic animal samples higher than those in water samples respectively.

To investigate the epidemiological trait of gastroenteritis of human caused by Campylobacter jejuni, isolation of etiological agent was carried out. Isolated C. jejuni were biotyped and serotyped. A total of 1929 specimens from 438 human, 182 milking cows, 200 cattle, 187 goats, 70 dogs, 426 pigs, 278 chickens, 148 duck, 50 raw milk, 110 chicken meat, 20 duck liver and 50 river water was examined for the presence of C. jejuni and C. coli by direct plating and enrichment techniques. Isolation rates detected in human, animals food and water were as follows : human 0.7 %, ducks 54.7 %, dogs 37.1 %, chickens 33.7 %, goats 26.7 %, cattle 25.5 %, pigs 19.9 % and milking cows 7.7 %. The organism was isolated from 65 % of 20 duck livers and from 20 % of 110 chicken meat. Campylobacter was not recovered from raw milk and river water. The majority of the isolated 201 strains of C. jejuni was classified as biotype I (53.7 %) and Biotype II (36.8 %). 117 strains of C. coli were 59.8 % of biotype I, 40.1 % biotype II. Isolated C. jejuni strains showed 13 different serotype, and serotype 4, 5, 26 and 36 were most frequent. C. coli strains showed 7 different serotype, and serotype 21, 25 and 29 were relatively common