S. Sornmani

Specific monoclonal antibodies to Opisthorchis viverrini

A Balb/c mouse was immunized with a crude soluble antigen of Opisthorchis viverrini adult worms (OVAA) over a period of 7 months. Spleen cells from the immune mouse were fused with Sp2/0 myeloma cells. Among the 264 tissue culture wells containing the fused cells, cells of 96 wells (36%) produced antibodies to the immunizing agent. Antibodies produced by cells in several wells reacted with antigens from other species of parasite. Cells of 17 wells produced antibodies specific only to OVAA, thus cells from three representative wells were cloned by limiting dilution. Hybrids obtained produced antibodies which could be classified according to their tissue specificities into three groups. The first group of antibodies reacted strongly to the worm integument and weakly with the muscles while those belonging to the second group reacted only to muscles of the worms. The monoclonal antibodies of the third group gave a positive reaction to both muscles and tegument.

Detection of Opisthorchis viverrini antigens in stools using specific monoclonal antibody

Detection of Opisthorchis viverrini antigens in stools using specific monoclonal antibody. International Journal for Parasitology 22: 527-531. A sandwich enzyme-linked immunosorbent assay (ELISA) was developed for detecting Opisthorchis viverrini antigen in faecal extracts of four groups of individuals. These were 24 patients with O. viverrini infection only (group 1), 31 patients with O. viverrini and other parasitic infections (group 2), 141 patients with other parasitic infections (group 3) and 21 normal, parasite-free individuals (group 4). The first antibody used in the ELISA was polyclonal immunoglobulin G prepared from the serum of a rabbit previously immunized with crude extract of O. viverrini. The second antibody was monoclonal antibody specific to an antigen located in the worm tegument and muscular tissue. Sensitivity of the assay was 31% while specificity was 100%. Considerations for improving the sensitivity are discussed.

Infection and re-infection rates of opisthorchiasis in the Water Resource Development Area of Nam Pong Project, Khon Kaen Province, northeast Thailand

A one-year investigation on re-infection rates of opisthorchiasis was carried out in three villages in the Nam Pong Water Resource Development Project, Thailand. In the two villages where selective population chemotherapy was combined with improvements in sanitation and health education aimed at changing food habits, the mean monthly re-infection rate was 2.0% and the annual cumulative rate was 21.5%. In the third village, where only selective population chemotherapy was carried out, the monthly re-infection rate was 5.0% and the annual cumulative rate was 55.5%. Studies on new infections in initially negative individuals were also carried out in the three villages, with inconclusive results.

An investigation of the health and nutritional status of the population in the Nam Pong Water Resource Development Project, northeast Thailand

The prevalence of gastro-intestinal parasites, the haemoglobin level, nutritional status (from anthropometric measurements), urinary urea-N creatinine (U-C) ratio and levels of vitamin B1, and B2, were studied in populations living around a man-made lake, in a resettlement area and nearby irrigation area and in traditional villages in northeast Thailand. The hydroxyproline (HOP) index was also determined.The intensity of parasitic infection was generally low, but Opisthorchis viverrini had the highest prevalence rate in the irrigation area and hookworm, Necator americanus, in the resettlement area. Despite a high average annual income per household in the irrigation area, no significant difference in the nutritional status was found, as judged by anthropometric measurements. The U-C ratio was highest in children around the lake. Anaemia was common in about 30% of the total population in the areas surveyed. The HOP index was similar in all areas. For vitamin B1, and vitamin B2 1·7–10·9% and 1·9–10·0% of th...

Mekong schistosomiasis. III. A parasitological survey of domestic water buffalo (Bubalus bubalis) on Khong Island, Laos.

Of 103 water buffalo (Bubalus bubalis) examined on Khong Island by means of the M.I.F.C. and hatching techniques, none were passing eggs resimbling those of the Mekong schistosome. One buffalo calf was infected with Orientobilharzia harinasutai and another with Schistosoma spindale; this is the first time these parasites have been reported from Laos. Since the buffalo that were examined had constant and year-round access to a part of the Mekong River that has been shown to be a site of heavy transmission of schistosomiasis to humans and dogs, it was considered that the buffalo would have acquired the infection with the human Mekong schistosome if this were possible. In the absence of buffalo necropsies, and since no eggs of the Mekong schistosome were detected in the stools of these animals, we assumed that they had either not become infected with this parasite or, if they had, that the infections did not produce eggs in the faeces which were detectable by the methods employed. On the basis of our examinations, it would not seem that domestic water buffalo are involved as reservoirs in the epidemiology of human schistosomiasis on Khong Island.