Cross-sectional surveys of parasitic infection were performed using the agar plate culture technique (APCT) and modified formalin-ethyl acetate concentration technique (MFECT) to assess the true prevalence of Strongyloides stercoralis relative to other parasites in north-east Thailand. The enzyme-linked immunosorbent assay (ELISA) for diagnosis of S. stercoralis infection was used to estimate the seroprevalence for comparison with coproprevalence. Faecal and serum samples were collected from study participants during October-November 2000. Within the sample population of 332 rural northeast Thais from 3 communities, S. stercoralis was the most common parasitic infection (average 28.9%, range 27.7-30.3%) as determined by APCT; by MFECT the average was 5.4% (range 1.8-8.6%). Other intestinal parasites by order of prevalence were Opisthorchis viverrini (average 14.2%, range 8.6-19.4%), hookworm (average 12.3%, range 4-20.2%), Echinostoma sp. (7.5%), Giardia intestinalis (0.9%), Trichuris trichiura (0.6%), and Taenia sp., Hymenolepis nana and Entamoeba coli (all 0.3%). In an analysis of a subset of the sample population for which serum samples were available (n = 120), coproprevalence by APCT was 33.3% (range 27-53.8%) and seroprevalence was 47.5% (range 29.7-57.9%) by modified unit-based ELISA and 34.2% (range 21.6-42.1%) by conventional optical density (OD)-based ELISA. Taking APCT as the reference method for diagnosis of strongyloidiasis, the sensitivity and specificity of the OD-based ELISA were 65% and 81.3%, respectively, and of the unit-based ELISA were 77.5% and 71.3%, respectively. Our results indicate that S. stercoralis is the predominant parasite in rural north-east Thailand, and that APCT and ELISA should be used as complementary diagnostic methods for community-based parasite surveys, at least among those in high-risk groups.

Abstract. We developed an enzyme-linked immunosorbent assay (ELISA) that detects filaria-specific immunoglobulin G4 antibodies in unconcentrated urine. The ELISA was positive in 87 of 91 (95.6%) urine samples collected from people with Wuchereria bancrofti microfilariae, antigen, or both. Of 298 urine samples collected in Thailand, Lao People's Democratic Republic, and Japan, where no human filariasis is known, 295 (99.0%) were negative by ELISA. Various intestinal nematode and fluke infections did not interfere with the ELISA. Urine samples with sodium azide could be kept at 37ЊC for 4 weeks, and the time of urine collection did not influence ELISA results. This ELISA can be used to identify endemic foci of filariasis.

SUMMARY Tuberculosis remains a major health problem worldwide in the era of HIV/AIDS. Co‐infection with intestinal parasites has been suggested to worsen the outcome of infection by polarizing the immune response towards Th2. This study investigated serum IgE levels of 241 tuberculosis patients and compared the IgE profiles in the tuberculosis patients either with or without intestinal helminthic infection and/or HIV infection. The serum levels of IgE in tuberculosis patients before initiation of antimycobacterial chemotherapy were found to be 1722 ± 1290 IU/ml (Mean ± SD) in HIV seronegatives and 2366 ± 1849 IU/ml in HIV seropositives. Further, the IgE level was significantly higher in patients coinfected with intestinal helminthes and HIV compared to those infected with helminthes or without coinfection (P < 0·05). Anti‐tuberculosis chemotherapy significantly reduced serum IgE levels in HIV seronegative tuberculosis patients (P < 0·05). These findings might indicate an active role of therapy in shifting the immune response towards Th1 which is crucial for prognosis in tuberculosis patients.

The in vitro effects of ethanol and aqueous extracts of the medicinal plant Cardiospermum halicacabum on adult worms and microfilariae of Brugia pahangi were investigated. With or without the plant extracts in culture medium, the motility of adult worms, microfilariae and microfilarial release from female worms were monitored daily. After 7 days of culture, viability or tissue damage of adult worms was assessed using the MTT assay. At > 500 μg ml-1, the aqueous extract significantly reduced motility of adult females after 24 h of exposure and adult males after 3 days. The aqueous extract, at > 500 μg ml-1, also significantly reduced microfilarial release from female worms, starting on day 2. The reduction in the motility of adult worms and the pattern of microfilarial release from female worms were concentration and time dependent. The MTT assay results revealed that adult worms cultured in the presence of aqueous extracts at > 500 μg ml-1 were damaged. However, the aqueous extract did not affect the motility of microfilariae with the exception of those in higher concentration extracts. Higher concentrations of ethanol extracts (2 mg ml-1) inhibited both the motility of adult worms and the release of microfilariae from females. Little effect of ethanol extracts was detected by the MTT assay, as only slight damage was caused to worms exposed only to the highest concentration (2 mg ml-1). However, ethanol extract at 500 μg ml-1 rapidly reduced the motility of microfilariae on day 2. The present study revealed that an aqueous extract of C. halicacabum has mild but definite direct macrofilaricidal action on B. pahangi.

The Brugia pahangi infective larval response to jird serum was studied using an agar plate assay. Larvae placed onto the agar remained at the same place for 60 min. Once the larvae were stimulated by serum, more than 95% oriented towards the serum and reached it within few minutes. This larval response was inhibited by an activator of phosphodiesterase (imidazole), adenylate cyclase inhibitors (SQ22536 and MDL-12330A) and protein kinase A inhibitor. An inhibitor of phosphodiesterase (IBMX), an activator of adenylate cyclase (forskolin) and an membrane permeant analogue of cAMP (8-bromo-cAMP), caused a number of larvae to move out from the inoculation area towards the other zones. To our knowledge, this is the first report of a chemotactic response by B. pahangi larvae to host serum. We conclude that B. pahangi larvae show a chemotaxic response to host serum, and that cAMP and cAMP dependent protein kinase are involved in the signal transduction.