Field trials in the control of Opisthorchis viverrini with an integrated programme in endemic areas of northeast Thailand.

A control programme of opisthorchiasis was carried out for three years in three villages of northeast Thailand in order to compare the effectiveness of two intervention measures. The intervention measures employed were to give praziquantel treatment to all infected people either once (village I) or twice (village II) per year with the integration of regular health education and sanitation improvement. A control village (village III) received no intervention during the study. Sampling of the population in these villages to estimate prevalence, intensity, reinfection and incidence of infection as well as knowledge of opisthorchiasis and number of latrines was performed at 6 monthly intervals throughout the duration of the study. At the initial assessment, there were no significant differences in the prevalence and intensity of infection of villages I and II. Both values were greatly reduced when assessed 6 months after the initiation of treatment, and the decrease in prevalence and intensity of infection did not differ between village I and II. The control village (village III), during the first 2 years, exhibited slight variation in the prevalence and intensity, and these decreased considerably in the third year of the study. The reinfection rate per 6 months in villages I and II was nearly equal. The incidence rate per 6 months in the two treated villages was lower than that of the control village. Marked improvement in knowledge of opisthorchiasis, behavioural changes of eating raw fish and increased numbers of latrines was evident in all of the villages during this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Excretory-secretory antigenic components of Paragonimus heterotremus recognized by infected human sera.

Antigenic components of Paragonimus heterotremus metabolic products were revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot analysis of sera from patients with P. heterotremus infection, from patients with other illnesses, and from healthy adults. By SDS-PAGE, it was found that the metabolic products comprised more than eight major polypeptides. Immunoblot analysis revealed 11 components which were strongly recognized by paragonimiasis antisera. These antigenic components had molecular masses ranging from less than 12.3 kDa to 144 kDa. One antigenic band of 31.5 kDa was found to give a consistent reaction with paragonimiasis antisera (97% sensitivity). Of the other patient sera, only sera from patients with Fasciola sp. infection reacted with antigenic bands of 56, 38, and 18.5 kDa. The present findings suggest that the 31.5-kDa component is sensitive and specific for the diagnosis of human P. heterotremus paragonimiasis.

Analysis of antibody levels before and after praziquantel treatment in human paragonimiasis heterotremus.

Enzyme immunoassays (ELISA) and Western blot analysis were used to determine IgG antibody levels in patients infected with Paragonimus heterotremus from Thailand before and after treatment with praziquantel. An IgG antibody ELISA showed that a substantial reduction of antibody levels occurred after one year of treatment. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis showed that P. heterotremus adult extract is highly complex, consisting of more than 9 antigenic bands with molecular size ranging from 123 kDa to less than 12.3 kDa. Two prominent bands of 31.5 kDa and 18.5 kDa were found to show consistent reactions with all serum samples from the pretreatment group. There was a marked reduction in the intensity of the reaction of the 31.5 kDa band with each serum sample from post-treatment patients but the other bands disappeared during the one year interval.

Seasonal variation in the prevalence and intensity of canine Gnathostoma spinigerum infection in northeastern Thailand.

Gnathostoma spinigerum was found in gastric nodules in 4.1% of 2940 dogs surveyed in northeastern Thailand. The prevalence and worm burden of G. spinigerum exhibited a seasonal fluctuation. The parasites were more abundant in the rainy season and the early winter (August-December) than in the summer (April-March). Most parasites were sexually mature between August and December while immature worms were observed during March and April. The distribution of gnathostomes within the sampled dogs was highly dispersed and few animals were found to harbour more than five worms.

Scanning electron microscopy of cuticular surface of the adults Paragonimus heterotremus in Phitsanulok, Thailand.

Scanning electron microscope observation of surface structure was made on adult Paragonimus heterotremus (Phitsanulok, Thailand) and the surface topography of the anterior end, suckers, body cuticle and papillae was described. The numerous thorn-like tegumentary spines were distributed all over the surface. The spines were well-developed and branched. The papillae were divided into two types: dome-shaped and ciliated. Two pairs of papillae were seen around the lip of the oral sucker, while those around the ventral sucker were not evident.

Antigenic components of Paragonimus heterotremus recognized by infected human serum.

The antigenic components of a Paragonimus heterotremus saline extract were revealed by SDS-PAGE and Western blot analysis using sera from 32 patients with P. heterotremus infection, 60 with other helminthiasis, and 15 normal human sera. It was found that the worm extract was comprised of more than 13 polypeptides, among which 5 components were strongly recognized by paragonimiasis sera. These components had approximately showed molecular weight of less than 12.3, 12.3, 18.5, 31,.5 and 38 kD. Only the 31.5 kD component was recognized by all 32 paragonimiasis sera. Sera from other helminth infections and from uninfected did not produce detectable bands with the worm extract. The present findings suggested that the 31.5 kD component may be sensitive and specific for the diagnosis of human paragonimiasis heterotremus.

Comparison of adult somatic and excretory-secretory antigens in enzyme-linked immunosorbent assay for serodiagnosis of human infection with Paragonimus heterotremus.

Adult somatic antigen extract of Paragonimus heterotremus was compared with excretory-secretory (ES) antigen in an enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of human paragonimiasis. The absorbence values in ELISA using the adult somatic antigen were not significantly different from the values obtained using ES antigens (P greater than 0.05). The sensitivity of the ELISA using either antigen was 100%, but the specificity was 96% with somatic and 98% with ES antigens due to a cross reaction with fascioliasis sera. It appears that both somatic and ES antigens are effective antigens for use in serodiagnosis of human paragonimiasis heterotremus.

Serodiagnosis of human paragonimiasis caused by Paragonimus heterotremus.

Enzyme-linked immunosorbent assay (ELISA) and indirect hemagglutination tests (IHA) were evaluated for serodiagnosis of human paragonimiasis caused by Paragonimus heterotremus using homologous adult worm extract as antigen. IgG-ELISA was the most sensitive, being positive in all paragonimiasis sera tested while IHA and IgA-ELISA gave 88% and 59% positive rates respectively. Cross reactivity in IgG-ELISA was detected with fascioliasis sera, producing overall assay specificity of 97%. It is suggested that IgG-ELISA is a reliable serodiagnostic test for human paragonimiasis caused by Paragonimus heterotremus.

Intracameral gnathostomiasis: a cause of anterior uveitis and secondary glaucoma.

Recognition of parasitic diseases by Western physicians is becoming increasingly important because of increased international travel and the recent influx of refugees from South east Asia. We describe two patients who presented with acute anterior uveitis and secondary glaucoma caused by intracameral third stage larvae of Gnathostoma spinigerum. The parasites were successfully removed, with preservation of good visual acuity. The initial infection may occur through consumption of contaminated water and/or raw or undercooked foods, while the eyes may be involved even years later. Accurate diagnosis and surgical removal of the parasites may save life.