Affinity purified oval antigen for diagnosis of Opisthorchiasis viverrini.

Monoclonal antibodies (MAb) were raised against an oval antigen of the liver fluke Opisthorchis viverrini which is the causative agent of a parasitosis, i.e. opisthorchiasis in Thailand. The antibodies were used in an affinity column to purify the O. viverrini oval antigen from a crude extract of adult parasites by chromatography. The oval antigen was then used in a membrane (dot) ELISA for detecting antibodies in serum samples of parasitologically confirmed Opisthorchis viverrini infected individuals (adult parasites were found in stools after praziquantel treatment and salt purgation), as well as of individuals infected with other parasites and parasite-free controls. The MAb-based dot-ELISA using the affinity purified O. viverrini oval antigen revealed 100% sensitivity, specificity and accuracy for detecting O. viverrini infection. The test is simple, rapid and highly reproducible. Several samples can be tested at the same time without the requirement for special equipment or much increase in testing time; thus it is suitable for mass screening for O. viverrini exposure, especially in new endemic areas. Furthermore using serum specimens could increase patient and community compliance compared to the conventional parasitological survey which uses stool samples for the detection of O. viverrini ova, without treatment and subsequent salt purgation, this conventional method shows a low sensitivity and is also unpleasant to both the sample donors and the laboratory technicians which has historically shown a further negative impact on the final outcome.

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.

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.

Study on the management of diarrhea in young children at community level in Thailand.

An evaluating study was carried out among 15,466 children from households randomized from 30 clusters from twelve provinces of twelve regions of Thailand. Results of this study revealed 5.13 per cent of incidence-rate of diarrhea among young children aged under five years with an average of annual prevalence of 1.3 per child. The overall mortality-rate and diarrhea associated death were 51.7 per 100,000 and 6.5 per 100,000 respectively. The utilization of ORS was 25.6 per cent while the using-rate of sugar salt solution (SSS) and the use of recommended home fluids were 2.8 and 33.8 per cent respectively. As for treatment, the intravenous therapy was 6.2 per cent and the use of different types of drugs varied from 18.0 to 21.3 per cent. Only 23.7 per cent of parents could correctly prepare the ORS. The authors have made recommendations for the strengthening of community health education aiming at better promotion of ORS and other home care practices for diarrhea as important measures for lowering mortality together with relating preventive interventions.