Treatment of Opisthorchis viverrini and intestinal fluke infections with Praziquantel.

The study was carried out from September to November 1997 in Phrae Province of northern Thailand. A total of 95 adult patients with Opisthorchis-like ova in their stools were randomly treated with two different manufactured Praziquantels. Group 1, consisting of 49 patients, received a single dose of 40 mg per kg Praziquantel manufactured by the Thai Government Pharmaceutical Organization. Group 2 (46 patients) received Biltricide at the same dosage. Haplorchis taichui, H. yokogawai, Echinostome spp., O. viverrini, Taenia saginata and Enterobius vermicularis were expelled in the stools after treatment. Minute intestinal flukes were detected in 64% of patients. O. viverrini was found in lower proportion of 17%. By formalin-ether concentration examination one stool specimen from each patient, the cure rate in both groups on the 30th day of treatment was 100%. The side effects of the two different Praziquantel treatments were mild with no significant difference. Praziquantel, regardless of its manufacture, proved effective against O. viverrini and other minute intestinal flukes (H. taichui, H. yokogawai and Echinostome spp).

Epidemiology of opisthorchiasis and national control program in Thailand.

Opisthorchiasis is a disease caused by opisthorchis trematode commonly known as liver fluke. In Thailand Opisthorchis viverrini is the only parasite of opisthorchiasis, the first case of opisthorchiasis was reported in 1911 by Leiper from the autopsy of corpse in Chiang Mai. Later on Sadun in 1953, Harinasuta and Vajjarasthira in 1961, and Wykoff in 1965 had demonstrated a complete life cycle of O. viverrini. History of opisthorchiasis control has dated back to 1950 as a small scale helminthiosis control program in some high risk areas. Following a number of studies and trial projects of the Faculty of Tropical Medicine of Mahidol University, the national liver fluke control program has been developed and operated under different National Public Health Development Plans. Presently, the program is being operated in some central provinces, and all northeastern and northern provinces of Thailand. The main strategies for liver fluke control are comprised of 3 interrelated approaches, namely stool examination and treatment of positive cases with praziquantel for eliminating human host reservoir; health education for a promotion of cooked fish consumption for preventing infection; and the improvement of hygienic defecation for transmission interruption. Data obtained from liver fluke control operation in 1996 show the countrywide prevalence of opisthorchiasis at 21.5% with a variation in all age groups. Differences of infection are also found among geographical regions. A large percentage of infection is mild infection. Comparing figures of 1981 and 1991, there is a considerable increase in the central and northern regions, while the northeastern region has significant decrease.

The impact of a decade long opisthorchiasis control program in northeastern Thailand.

Based on the figures obtained from a regional survey in 1981, the overall prevalence of opisthorchiasis in northeastern Thailand was as high as 34.6%. Traditional consumption of improperly cooked fish dishes and unhygienic defecating habits among rural inhabitants have been recognized as significant factors determining such high prevalence of this liver fluke in that area. Following experience of Mahidol University's Faculty of Tropical Medicine in Thailand of treating liver fluke infected individuals with praziquantel, the Ministry of Public Health started a liver fluke control program in the northeast as special service units in 1984 in 4 provinces. In 1988, the program was expanded to cover all 19 northeastern provinces, services being rendered at a community level covering stool examination and treatment of positive cases. Intensive health education was integrated as one element of liver fluke control program. During the early phase of operation (attack phase) a mobile stool examination team was the crucial strategy for active service. Following the attack phase, passive service was operated at each health service facility provided that results of population based program evaluation in each area showed a low prevalence according to the set target. Regionwide assessments in 1991 and 1992 indicated a declining trend of prevalence from 34.6% to 30.19% and 24.01%, respectively. In 1994, a population-based sampling survey was carried out to measure the effect of the liver fluke control program over 10 years operation (1984-1994) on both behavioral outcomes and prevalence impact. Sample for the assessment of behavior were 1,268 individuals, while another 1,912 samples were used for determining disease prevalence. Health related behaviors regarding frequent consumption of uncooked fish dishes decreased from 14% in 1990 to 7% in 1994 while occasional consumption remains as high as 42%. The prevalence of opisthorchiasis is 18.5% with a large variation in infection rate (5.20-56.25%).

Evaluation of hookworm control program in southern Thailand.

An intensive hookworm control program providing the rural population of southern Thailand with mass treatment with 300 mg Mebendazole and health education commenced in 1989 with a yearly budget of over US$ 1.2 million. The current research aimed to evaluate the coverage of health education and mass treatment, the effectiveness of mass treatment and the administrative process of the control program, two years after its commencement. This evaluation consisted of three studies. In the first study, 120 villages were randomly selected, from which 840 school children, 843 adults aged between 15-59 and 844 subjects aged over 60 years were interviewed to assess awareness of hookworm, latrine availability, receipt of and compliance with antihelminthics provided, and self-treatment. In the second study, 8 villages from each of the 14 provinces were randomly chosen. Stool samples from randomly selected 4,434 subjects were examined. The third study consisted of interviewing key health planners in Bangkok and 71 health officers/workers from 32 samples villages of 8 sampled provinces. Latrine availability was 80%. Percentages of subjects who had ever heard of hookworm ranged from 70 to 95 in school children, 55 to 80 in adults and 25 to 58 in the older age group. While 63 to 85% had latrines in their homes, 27% to 47% admitted defecation outside in the past month. Percentages of coverage of drug treatment ranged from 82 to 91 in school children, 68 to 80 in adults and 54 to 59 in the older age group.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study on the efficacy of albendazole and mebendazole in the treatment of ascariasis, hookworm infection and trichuriasis.

A comparative study of the efficacy of albendazole and mebendazole was carried out in Pattani Province in the southern part of Thailand. One hundred and ninety-six patients with single or multiple infections with Ascaris, hookworm, and Trichuris were randomized into 4 groups for different treatments. Stool examination by Kato-Katz technique were done before and on day 14 after treatment. Results of the study showed that (1) a single dose of 300 mg mebendazole (locally produced) resulted in cure rates of 50%, 0% and 0% and egg reduction rates of 87.3%, -15.3%, and 28.3%, for ascariasis, hookworm infection and Trichuris respectively; (2) a single dose of 300 mg mebendazole (original) resulted in cure rates of 100.0%, 9.1%, and 43.3%, and egg reduction rates of 100.0%, 72.0%, and 77.9%, for Ascaris, hookworm, and Trichuris respectively; (3) a single dose 500 mg mebendazole (original) resulted in cure rates of 100.0%, 30.2%, and 70.3%, and egg reduction rates of 100.0%, 70.4% and 89.9%, for Ascaris, hookworm, and Trichuris respectively and (4) a single dose of 400 mg albendazole (original) resulted in cure rates of 100.0%, 84.3%, and 67.4%, and egg reduction rates of 100.0%, 96.0% and 87.0%, for Ascaris, hookworm, and Trichuris respectively. Both mebendazole and albendazole are safe and no side effects were observed. The results of this study suggested that albendazole is the preferred benzimidazole derivative for mass treatment of multiple infections with Ascaris, hookworm, and Trichuris.