A cross-sectional study of intestinal parasitic infections among schoolchildren in Nan Province, Northern Thailand.

A cross-sectional study of the prevalence of intestinal parasitic infections at eight schools in Bo Klau district and four schools in Chalerm Prakiet district, Nan Province, in January and February, 2001. A total of 1,010 fecal samples were examined using the formalin-ether sedimentation technique. Results revealed that the rate of helminthic infection was 60.0%, while protozoa accounted for 36.2% of infections; mixed infections were common, resulting in a total prevalence of both parasites of 68.1%. Helminthic parasites, listed by frequency of infections, were Ascaris lumbricoides (21.7%), hookworm (18.5%), Trichuris trichiura (16.3%), Opisthorchis viverrini (1.7%), Strongyloides stercoralis (0.9%) and Enterobius vermicularis (0.9%). The protozoal infections were Entamoeba coli (25.8%), Giardia lamblia (5.3%), Endolimax nana (2.5%), Entamoeba histolytica (1.4%), Blastocystis hominis (0.8%), Chilomastix mesnili (0.3%) and Iodamoeba bütschlii (0.1%). This study emphasizes the need for improved environmental hygiene ie clean water supplies and enhanced sanitation, in affected communities. Health promotion, by means of a school-based educational approach is recommended; regular check-ups should be implemented, and a continuos program of treatment should be considered.

Prevalence of Opisthorchis viverrini infection among villagers harboring Opisthorchis-like eggs.

The precise occurrence of Opisthochis viverrini infection in humans, who were positive for Opisthorchis-like eggs in a stool examination, was determined using the potassium permanganate staining method. In the 68 specimens examined, there were more individual O. viverrini eggs (38.24%) than singular Haplorchis taichui eggs (29.41%). One-fourth of the total specimens contained a mixed infection of O. viverrini and H. taichi eggs. The median ratio of O. viverrini: H. taichui eggs in mixed infection cases was 2.29 (min = 1, max = 17.5). It is suggested that chemotherapy with praziquentel treatment should be given to patients who are positive for O. viverrini-like eggs.

Hymenolepis nana infection in Thai children.

Stool examination was performed on 2,083 Thai children from orphanages and primary schools. Hymenolepis nana infection was found only in children from orphanages with a prevalence of 13.12 per cent. Males had a statistically significant higher prevalence of infection than females. Most infected children were asymptomatic. In symptomatic infected children, the symptoms were mild and non-specific such as pruritus ani, abdominal pain, diarrhea, anorexia, headache, and dizziness. Praziquantel in a single oral dose of 25 mg/kg body weight was effective and well tolerated in Hymenolepis nana infected Thai children.

Opisthorchiasis and intestinal fluke infections in northern Thailand.

Four hundred and thirty-one residents from 16 provinces in northern Thailand who had previously been found positive for Opisthorchis viverrini or Opisthorchis viverrini-like eggs were given praziquantel 40 mg/kg. The stool was collected for 4 to 6 times and examined for adult worms. The prevalence of Opisthorchis viverrini in this group was 11.6%. Intestinal flukes, Haplorchis taichui and Haplorchis yokogawai, were predominantly found in 63.11% and 10.44% respectively. Other intestinal flukes (Centrocestus caninus, Echinostoma malayanum, Haplorchis pumilio, Phaneropsolus bonnei, Plagiorchid flukes, Prosthodendrium molenkampi and Stellantchasmus falcatus) were also found in small numbers.

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).

Overview reflection of primary health care in Thailand supported from 1976 to 1996 by Japan-Thailand partnership.

The international health cooperation of Japan for developing countries has been mostly concentrated on matters such as improvement of hygienic environment, prevention of tropical infectious diseases, establishment of hospitals with modern medical instruments and devices, and dispatch of medical experts. PHC (Primary Health Care) activities based on voluntary participation of local inhabitants in developing countries have been largely neglected. In the field of health and medical care, sufficient effect may not be achieved unless the local health activity is based on voluntary participation of the inhabitants. The introduction of advanced modern medical technics may be beneficial to some of the inhabitants, while most of the local inhabitants may not have the chance to receive such benefits, and additionally it is difficult to propagate modern medical care and technics widely to rural areas. In Thailand, PHC activity based on community participation was started in 1985, with the following three main themes: (1) Training of Village Health Volunteers (VHV) and Village Health Communicators (VHC), and development of their activities. (2) Establishment and operation of Health Centers. (3) Establishment and operation of a Drug Cooperative System (DC). Earlier, one of PHC activities developed by Japan, "Thailand Local Health Activity Improvement Project" based on the program of Thailand-Japan Partnership, was initiated in 1976 in rural areas of Chanthaburi Prefecture. From 1982, third country training programs have been carried out by the Japan International Cooperation Agency (JICA). As 10 years have elapsed since the initiation of PHC activity in rural areas in Thailand under the cooperation of the Governments of Thailand and Japan, it seems to be time to reconsider how PHC activity should be developed in future based on a candid evaluation of achievements and results.

Human infection of Centrocestus caninus in Thailand.

Examination of fecal samples, collected after treatment with praziquantel, of the persons positive with opisthorchioid eggs residing in the northern provinces of Thailand, was carried out. Five adults Centrocestus were recovered in one sample from Doi Saket, Chiang Mai and one adult was found in another fecal sample from Wiang Pa Pao, Chiang Rai. The worms had 26-30 spines arranging in two rows around the oral sucker which agreed with the character of C. caninus. This is the first record of natural human infection with Centrocestus in Thailand.

Intestinal sarcocystosis in Thai laborers.

To determine the prevalence of Sarcocystis and other intestinal parasites in Thai laborers who were going abroad for work, stool examinations of 362 asymptomatic laborers were studied. The four most frequently parasites found in stool were Sarcocystis sp (23.2%), Opisthorchis viverini (40.3%), hookworm (21.5%), and Strongyloides stercoralis (14.1%). Giardia intestinalis (5.2%), Entamoeba coli (1.7%), Endolimax nana (2.5%), Blastocystis hominis (4.1%), Echinostoma sp (3.6%), Trichuris trichiura (0.3%), Taenia sp (1.7%), Hymenolepis nana (0.6%), and Enterobius vermicularis (0.3%) were present at low rates. Sarcocystis were frequently found in male laborers (83.3%) (p < .01). The laborers from northeastern Thailand (n = 278) had a higher prevalence (26.6%) of Sarcocystis infection (p < .01). This study shows that Thai laborers, particularly from northeastern Thailand, are commonly infected with intestinal parasites. The high prevalence rates of Sarcocystis and other intestinal parasites in this study were indicative of the local habit of eating raw beef and pork, poor living conditions, and low levels of hygiene in Thai laborers. Sarcocystosis could be a significant food-borne zoonotic infection in Thailand.

Occurrence of the infective stage of Angiostrongylus cantonensis in the yellow tree monitor (Varanus bengalensis) in five Provinces of Thailand.

Twenty-two yellow tree monitors (Varanus bengalensis) were trapped and transported from 5 provinces, namely Lampang, Phitsanulok, Kamphaeng Phet, Tak and Prachin Buri to look for the infective larvae stage of Angiostrongylus cantonensis. In 4 provinces all of the yellow tree monitors were infected with the infective stage larvae of A. cantonensis altogether. Twenty-one of the 22 yellow tree monitors (95.5%) in the five provinces were infected. Our results of this study extend our knowledge of natural prevalence of A. cantonensis in yellow tree monitors. The snail eating habit of the yellow tree monitor might possibly be the source of the larvae.

Multi-infection with helminths in adults from northeast Thailand as determined by post-treatment fecal examination of adult worms.

Six hundred and eighty-one residents from 16 provinces in northeast Thailand who had previously been found positive for Opisthorchis viverrini and Taenia spp. eggs were given 40 mg Praziquantel (Bayer, Germany), per kg body weight. The total stool output for one to three days was collected and examined for adult worms. The prevalence of O. viverrini in this group was 92.4%. The intestinal flukes Echinostoma malayanum, E. ilocanum and E. revolutum were found to be high in males, with 8.3%, 8.1% and 0.8%, respectively. Minute intestinal flukes such as Haplorchis taichui, H. pumilio, H. yokogawai, Phaneropsolus bonnei, Plagiorchis harinasutai, Prosthodendrium molenkampi and Stellantchasmus falcatus were found to be 7.8%, 6.2%, 2.9%, 15.0%, 0.7%, 19.4% and 0.3%, respectively.

Effects of sensitization on efficacy of mebendazole in mice infected with adult Angiostrongylus costaricensis.

The relation between immunopotentiation and efficacy of mebendazole in sensitized mice infected with adult Angiostrongylus costaricensis was investigated. When compared with the non-treated control, the sensitized control showed better results in almost all parameters with a few mice being positive for the first-stage larvae in feces and eggs in the intestinal section. The results suggest development of protective immunity in the sensitized mice though it was not completely effective for inhibiting infection, worm growth and their functions. The immunity seemed to be developed by producing specific antibodies against the larvae by sensitization. Among 4 infected groups, the sensitized-treated group had the best results in all parameters especially in worm recovery and worm body length which referred that drug action was enhanced by the sensitization.

Parasitic infection and socio-demographic characteristics of urban construction site workers.

The socio-demographic characteristics and prevalence of parasitic infection of 117 (96 males and 21 females) construction site workers were investigated by means of questionnaires and stool examinations. The age characteristics of the individuals investigated varied widely from 15-60 years with a high percentage in the 21-30 years age range, no sex differences were discovered. Most of the workers received primary education even though some of them did not complete it. The percentage of illiteracy in females was quite high (9.5%) compared with males (2.1%). About 60% and 20% of these construction site workers migrated from the northeastern and northern regions of Thailand, respectively. 79.3% of male and 94.7% of female workers were found to be infected with parasites. Hookworm and Opisthorchis were predominant parasites.

Enzyme-linked immunosorbent assay based on monoclonal and polyclonal antibodies for the detection of Entamoeba histolytica antigens in faecal specimens.

A murine monoclonal antibody (MAb) (Eh208C2-2) raised against crude lysate of the pathogenic HM-1:IMSS strain of Entamoeba histolytica was used in an enzyme-linked immunosorbent assay for the detection of E. histolytica antigens in faecal specimens. The detection limit of the assay was 110 and 280 amoebae/ml of the HM-1:IMSS and HK-9 strains in phosphate-buffered saline, respectively. The assay was applied to single stool samples from 3 groups of individuals comprising 40 patients whose stools were positive for E. histolytica trophozoites and/or cysts (group I), 48 patients whose stools were negative for E. histolytica but positive for other parasites (group II), and 36 parasitologically-negative healthy controls (group III). Positivity rates of 77.5%, 2.1% and 2.7% were found in samples from groups I, II and III respectively. Specificity, positive and negative predictive values, and efficiency of the assay were 97.6%, 93.9%, 90.1% and 91.1% respectively. When group I samples were further divided into a trophozoite-positive subgroup IA (13 samples) and a cyst-positive subgroup IB (27 samples), the positive rates were 100% and 66.7%, respectively (P < 0.025).

Fecal egg output in relation to worm burden and clinical features in human opisthorchiasis.

A study of the relation of fecal egg excretion to worm burden and clinical features was carried out in 45 opisthorchiasis patients who had no signs of biliary obstruction. The fecal egg excretion was consistent and correlated with the worm burden. Although there was no definite association between clinical signs and intensity of infection, mild hepatomegaly and thickened wall or dilatation of the gallbladder were found more commonly in heavily infected patients. Eosinophilia was observed more often than previous reports. Concomitant parasitic infections were found in 82% of the patients. After praziquantel treatment, egg counts increased greatly during the first few days then decreased to very low levels in 7 days.

Intestinal perforation due to Macracanthorhynchus hirudinaceus infection in Thailand.

The ninth record of a human infection with the acanthocephalan worm Macracanthorhynchus hirudinaceus in Thailand is reported. The parasite was removed during laparotomy after perforation through the intestine of a 30-year-old woman.

A new intestinal fluke, Plagiorchis harinasutai n.sp.

Dilution-sedimentation examination of stool specimens from four opisthorchiasis patients treated with praziquantel led to the discovery of six Plagiorchis worms. This is the first known report of plagiorchis infection in man in Thailand. The morphological features differed from those of previously described Plagiorchis species indicating that these worms belong to a new species, which we designated as Plagiorchis harinasutai n.sp. in honour of Professor Chamlong Harinasuta, former Dean of the Faculty of Tropical Medicine, Mahidol University, Bangkok. The holotype is held at the Museum and Reference Centre. Paratypes are held in the Bangkok School of Tropical Medicine, Faculty of Tropical Medicine, Mahidol University.

The optimum dose of Puag-Haad in the treatment of taeniasis.

Forty-two per cent of 24 patients with Taeniasis saginata were cured by two-gram dose of a crude aqueous extract of the wood Artocarpus lakoocha, Puag-Haad, while eighty per cent of 25 patients were cured by three-gram dose which is comparable to the results of five-gram dose but had less side-effect. Thus, the three-gram dose of Puag-Haad is recommended in the treatment of taeniasis.

Detection of antibodies against Opisthorchis viverrini in patients before and after treatment with praziquantel.

Levels of antibody in sera of 78 patients with opisthorchiasis, 30 patients with other liver diseases, 10 patients with schistosomiasis and 30 healthy individuals were compared using three serodiagnostic tests, namely indirect haemagglutination (IHA), enzyme-linked immunosorbent assay (ELISA) and lectin immuno test (LIT). The geometric mean reciprocal titer in sera of opisthorchiasis patients was significantly higher than patients with other diseases, patients with schistosomiasis and healthy individuals (p less than 0.00001). After treatment with praziquantel, the antibody titers were decreased and became lowest 120 days after treatment. A statistically significant decrease from the pre-treatment sample was observed only at 120 days after infection and not earlier and only with ELISA (p = 0.03) and not with IHA and LIT (p greater than 0.05). Even with ELISA, significant decrease in antibody titer was apparent only when the pre-treatment sera had high enough antibody titer. ELISA was therefore better than the other two tests for the assessment of cure provided that the titer of pre-treatment sera was high.